supplement to User Manual
Contents
1. or 100 As energy is removed the meter measures the amp hours removed from a full battery and during any subsequent charging measures the amp hours returned to keep track of how much energy is in the batteries The Battery Full is based completely on the amp hour from full measurement and also on the value of total amp hours capacity of your battery set which you must program into the TriMetric Since the Battery Full display is based on amp hours it is important to understand amp hours first Ampere hours from full and Battery Full As was mentioned already the most important function of the amp hour from full display which is an extra data function shown on the panel is to measure the energy content of the batteries especially when the battery set is not at the extreme high or low end of charge or discharge which is the case most of the time This is particularly useful to plan your electrical usage avoid over discharge of the battery set and to know when to turn on the generator This will be described later in explicit detail in section C3 Amp hours is a measure of accumulated amps or amps multiplied by time called charge For example if energy is being taken from the batteries such that the amps display on the TriMetric shows 10 minus 10 amps the amp hour from full display will gradually decrease until after one hour the amp hour display will2. time minimizes the danger of overfilling The TriMetric Model 2020 battery reminders feature is useful to remind you when to equalize This is just a timer which you reset to O when you equalize the batteries After for example 45 days which number you may program into the TriMetric the battery reminders light will flash and Ch E will flash in the display every 12 seconds to remind you to equalize again After you equalize batteries you can reset the Days since equalized function by pushing the reset button while days since equalized is displayed until the display flashes 3 times This turns off the reminder which will reappear to remind you to equalize again after 45 more days have elapsed Other miscellaneous battery maintenance items not related to meter measurements 13 Periodically check and maintain water level of wet cell batteries Every 2 3 months check the battery water levels They should not be allowed to fall below the top level of the plates and should be filled up to the marker often the bottom of a cylindrical hole covered by the battery cap Add pure distilled water only and as mentioned the best time is just after equalizing the batteries Keep batteries at correct temperature range Ideal temperature is 60 80 F 15 25 C At higher temperatures batteries suffer reduced life At lower temperatures they have reduced capacity however even at 32 F 0 C they have about
3. 70 capacity although they don t absorb charging current as readily so it takes longer to charge them fully If batteries sit below 20 F they can freeze if in a low state of charge which will destroy the battery If they are kept reasonably well charged 75 or greater however they won t freeze even at minus 40 F Occasionally check connections Battery connections can sometimes develop excessive resistance This will cause apparent loss of capacity and possibly improper charging of some batteries in a parallel group which can cause battery damage A section in Part 2 of this guide to be written will describe an easy and reliable way to do this using a hand digital voltmeter by measuring the voltage drop across connections while discharging the battery Keep tops reasonably clean Battery tops being horizontal surfaces sometimes collect quite a bit of dirt Occasionally clean these off to reduce possibly of stray current leakage 3 Using the TriMetric to minimize generator usage When it is necessary to use the generator to supplement energy input to fully charge the batteries it is usually desirable to reduce the generator time for several reasons including cost air and noise pollution caused by the generator Here is a good strategy for doing recharging to reduce generator time and also increase battery life It is based on two important facts Fact 1 The generator charging rate in amps is greater and often much greater than r
4. be seen one important factor influencing the volts reading is the state of charge of the batteries State of charge will be defined again later but it means how full the batteries are Very generally the battery voltage gradually goes up as the batteries acquire more energy through being charged and goes down as energy is removed Often simple battery full empty gauges which are intended to show how full the battery is use only this volts measurement Variations on this theme are simple voltmeters that control green yellow red indicator lamps often conditioned by a time delay that give a rough indication of state of charge The difficulty of using volts to accurately measure state of charge is that the voltage reading is also affected by how many amps are being used to charge and discharge If the batteries have not been either charged or discharged for awhile several hours the volts reading can be used to get a good idea of state of charge However if the battery is being discharged by a load the volts reading will be pulled down depending on how many amps are being discharged If you start charging them again the voltage will immediately be pushed up by the charger again depending on how many amps are charging However there are two extreme situations where the volts reading is particularly useful to tell the battery state of charge one is while the batteries are nearly fully charged while they are being charged In this
5. case the battery voltage will start to climb more rapidly and show a value for a 12 Volt system of from 14 2 volts or higher Double this for 24 V systems At the other extreme while discharging the voltage reading can be relied upon to show that the batteries are nearly depleted of energy when the reading goes below 11 2 volts for 12 volt systems double for 24 volts and will start to decline more rapidly from there But as mentioned when the battery is in intermediate states of charge the voltage curve is flatter meaning that the voltage doesn t change as much so it doesn t work well to gauge the state of charge As we will describe very shortly the amp hours from full measurement and the Battery Full display which is based on the amp hours from full are much more reliable indicators of state of charge in this intermediate region Table 1 above shows the normal range of volts for various conditions of battery state of charge charging or discharging current and temperature An important use of the volts reading on the monitor is to check that the charging system regulators are working properly The charging systems which includes the system charge controller should charge the battery volts up to a certain point then stop charging or the batteries can be damaged by excessive charging Similarly if the voltage does not rise high enough the batteries can be chronically under charged which will
6. judge how full the batteries are it gives a number that is accurate to 5 10 when the charged parameters are correctly matched to the charging system as described in section E 1 This is quite adequate for a practical system and is typically much more accurate than monitors that measure only battery voltage which is another way to get a very rough idea of how full the batteries are Incidentally this is the System accuracy for a practical system with lead acid batteries not the TriMetric amp hour measurement accuracy which is much more accurate at 1 However after many days when the batteries are not fully charged the meter can gradually lose track of the exact charge state For this reason it is necessary to periodically resynchronize the battery set by recharging which resets the amp hour number to 0 and the Batt Full to FUL This is not only a good idea for the sake of meter accuracy it is also necessary to keep lead acid batteries in good condition to fully charge them occasionally Once a week is a reasonable rule for both reasons The Days since Charged display an extra display shown at the bottom of the front panel allows you to see how long ago in days since the TriMetric detected that the batteries were fully charged Battery reminders display Another feature of the TriMetric is the battery reminders display which has three different functions One function the days since charged d
7. repeatedly The six extra data displays show 1 Amp hours from full AH 2 How many days since the battery has been fully charged dSC 3 How many days since the battery has been equalized dSE 4 The cumulative lifetime amp hours discharged CAH 5 Highest battery voltage since last reset OHI 6 Lowest battery voltage since last reset bLO 1 Using amps Amps or more properly amperes are a measure of electrical current or the rate at which electricity flows through a wire at a certain point analogous to the gallons minute of water flowing in a pipe The higher this rate the more rapidly electrical energy flows Electrical current flows from your batteries into a load at a certain ampere rate for example 5 amperes and the higher the rate the more quickly the batteries will be discharged As will be mentioned soon volts are a measure of how hard that flow is being pushed analogous to water pressure in a pipe Current is usually measured by breaking the wire and inserting an ammeter which completes the circuit and measures the flow Current supplied by the solar array when the sun is shining has a certain number of amps typically 2 to 5 amps per solar panel in full sun and electricity is consumed by the electrical loads at a certain number of amperes from 0 1 to over 100 depending on the load when they are operating The value to you of measuring amps is that it enables you to see how
8. result in sulfation and thereby shorten battery life The TriMetric can record and save the highest voltage which occurs while finishing a charge so it can easily allow you to occasionally check this value of maximum charge voltage and therefore check that the charge controller is adjusted and operating properly The easiest way to check this maximum value is by using the maximum voltage bHI display which is an extra data function shown on the bottom of the panel Before using it for this purpose you should use the select button to switch to this display reset the voltage to the present battery voltage by holding down the RESET button until the display flashes for 3 times It will now track the battery voltage as it goes higher but will not go down as the voltage goes down thus showing the maximum voltage that the batteries attained until you again manually RESET the value After the solar array or other charger has finished charging the batteries you can then check this display to see the maximum voltage attained 3 Using Battery Full This display shows how much energy is left in your batteries Here is a quick synopsis of how this measurement is made to be more fully explained in the next section The TriMetric senses when the battery is fully charged when the volts goes sufficiently high and the charging amps become sufficiently low It then resets the Battery Full reading to FUL
9. It is quite practical today to use solar or other renewable energy for powering a home much more so than 15 years ago Some reasons for this are Availability of reliable high efficiency inverters that convert battery power at high efficiency to AC power usable by ordinary electrical appliances for 24 hours a day Lower energy requirements of many electrical devices such as TV s computers and electric lighting Cost of solar panels that can convert light to electricity is going very gradually down while grid power has gone gradually higher As grid power costs go higher in the future even more people will find renewable energy practical Lack of subsidies to extend grid electricity In many cases when electric lines must be run a significant distance to reach the grid one half mile if your energy requirements are not too great it is cheaper to use off the grid systems because of the high cost of connecting to the grid Limitations of such systems Despite their practicality for many people there are some limitations that must be understood by users of such systems Higher cost per kW hr Electricity from small renewable energy systems still costs quite a bit more per kilowatt hour of energy than that produced from the electrical grid from 3 to 10 times more expensive so conservation becomes more important However if a small number of high energy using devices are avoided such as space heaters hot water heaters and air conditioners thi
10. Part 1 Using the TriMetric or other battery system monitor to maintain your battery system conserve energy and troubleshoot system problems Newly revised for TM 2020 Available on the Internet at www bogartengineering com Part 1 Sections A C For beginners Volts amps and amp hours are defined and their use is explained in a renewable energy system Basic lead acid battery care is described Part 2 Intermediate advanced To be written later Troubleshooting renewable energy system problems Analyzing system performance Battery capacity resistance and efficiency measurement Checking charge controllers Charging batteries Other battery types Other topics Bibliography on renewable energy systems to be compiled A bibliography of catalogs and books available related to powering a home with renewable energy Comments and suggestions for improvement are welcome How to get what you want from this guide For day to day usage of your TriMetric or other system monitor read Part 1 Sections A C Section B is necessary background and section C contains specific suggestions for use For more advanced information on troubleshooting a renewable energy system problems read Part 2 Sections D F If you want the minimum information to understand how to use the TriMetric read the parts of sections B C that are not labeled optional Copying and distribution of Part 1 is welcome if copied and distributed without changes and in it
11. attery chemistry check with a dealer or other person knowledgeable about this Battery philosophy Energy systems and credit cards There seem to be two opposite styles of using a credit card Some people use their credit cards frequently but pay off the balance each month and rarely if ever go even near their credit limit Then there are other opposite types of people that carry a large balance from month to month and only stop spending when they ve exceeded their credit limit They pay the minimum amount necessary and go to the next month The interesting thing is that it doesn t cost any more in the long run to pay the balance off each month in fact even less because interest is being saved It is similar with renewable energy systems Lead acid battery systems last longer if they stay relatively full rather than relatively empty so keeping them always at low charge will reduce battery life rather like paying extra interest on your investment If you keep them relatively full they will last longer Since all the energy used must be generated at some time within limits it makes sense to keep them closer to the full side rather than empty However one can go overboard the other way too and insist on having a solar array that will fully charge them every day before noon Batteries unlike the bank are limited in their ability to store so although it s good for their health to overcharge them slightly excessive zeal to insure that the batterie
12. be exactly 10 less than it was indicating that 10 fewer amp hours are stored in the battery Similarly for every hour that the display shows 10 amps when the batteries are being charged the TriMetric will add almost 10 amp hours The almost has to do with efficiency factor and will be explained shortly Here s how the TriMetric keeps track of how full the battery is 1 the battery must be fully charged as a starting reference point 2 The amp hour from full number is then reset to 000 amp hours and the Battery full display is reset to FUL or 100 either manually or automatically as will be soon described which indicates a fully charged battery From there as the battery is discharged the amp hour display keeps track of the amps leaving by counting down to show a gradually more negative value so 40 amps or 40 amps discharging for 1 2 hour would subtract 20 amp hours from the total giving a total of minus 20 amp hours meaning that the battery is 20 amp hours away from full Eventually after removing as many amp hours as the battery holds the battery becomes discharged which means that the battery volts would have dropped too low to be useful At that point the amp hour from full display would have a negative value which is equal to the number of amp hours required to completely discharge the battery starting from a fully charged state which is called the capacity of the battery system The capacity in am
13. dition as described in the TriMetric instructions you may program the battery reminders function to remind you to recharge the batteries if they have not reached charged in 5 days or any other number of days that you choose If you sometimes use a generator to recharge your battieries the section below Using the TriMetric to minimize generator usage will be useful Lead acid Battery Rule 4 If you have flooded lead acid batteries equalize every 1 2 months Equalization is a term often given to describe the process of occasionally over charging the batteries Over charging is not necessarily synonymous with abuse it just means to put in more energy than the batteries can hold One purpose of equalization from which the name is derived is to cause all the individual series cells in the battery to become equally charged However it serves other functions as well A second function is to do a very complete charge of the battery When the battery is charged enough for the TriMetric to sense that the batteries are charged the battery usually is not yet 100 charged although it is generally over 85 charged If some of the battery reaction products remain in their uncharged state too long they undergo changes that make it very difficult to reconvert them back to their charged state thus making the battery progressively more difficult to fully charge This is referred to as sulfation of the battery which causes eventua
14. enewable sources such as solar or wind Generally the renewable energy resource is available for a long period but at a lower charging rate amps Fact 2 Batteries are willing to absorb energy the fastest rate when they are at lowest state of charge As they become more fully charged it takes more time to absorb the energy properly If you try to charge too fast at the end of charge it just drives the voltage up without actually charging the battery any faster This can waste energy and overheat the batteries without accomplishing real charging The conclusion from these facts is that for greatest efficiency the generator should be used to charge batteries when batteries are at a low state of charge and the solar array should be used for doing the charging when the batteries are more fully charged One wrong way use the generator is to wait until the solar array gets the batteries as close to charged as possible then when you see you re not going to make it with the solar array turn on generator to get the rest of the way It is more efficient to use the generator when batteries are at lowest battery full or amp hour from full point for example in the later part of the evening or early morning before significant sun if solar is expected in the daytime Strategy for using the monitor to know when and how long to run generator For minimum generator usage estimate how many amp hours your solar array or other source will be able to cha
15. g time as will be described specifically in section C3 Incidentally usually it is a good idea to enter a value of capacity that is less than the capacity value advertised by the battery manufacturer Then the Battery full display will show a conservative value lower than actual battery state of charge Also the battery manufacturers tend to be optimistic when rating their batteries and their number only applies after the battery has been really well charged and when the battery is 77 degrees f or higher which usually won t be the case in your practical system Charge efficiency factor Since batteries aren t perfect storage devices you can t get back all the energy you store into it some is lost The TriMetric compensates for this by an approximation which doesn t count the amp hours charging quite as much as the amount discharging For example if you discharge the battery at 20 amps for 5 hours the amp hour reading will always become more negative by exactly 20 x 5 100 amp hours But when you charge the battery at 20 amps for five hours the number will go positive by slightly less than 100 typically 94 to 98 amp hours How much the charging energy is discounted may be set by you to approximate your system depending on the battery type and age and it is called the charge efficiency factor If 100 amp hours of charge are added to the batteries but only 96 amp hours are added to the amp hour reading this represen
16. iency factor entered in the TriMetric is high is that the number entered is not the true overall charge efficiency factor of the battery since overall charge efficiency needs to also take into account the charging at the very top of charge when the battery is least charge efficient since some of the charge going in is causing the battery to convert water to hydrogen and oxygen instead of going into useful energy The number entered in the TriMetric is the charge efficiency excluding the top end of charge and when this is excluded the lead acid battery is very charge efficient Incidentally this is also why amp hours work so well to measure the battery state of charge State of charge and Depth of discharge These are percentages indicating how full or empty the battery is State of charge is the opposite of depth of discharge A fully charged battery has a state of charge equal to 100 and a depth of discharge 0 When empty these percentages are reversed For example if the capacity of the battery system is 200 and the amp hour reading is minus 20 the batteries are at 90 state of charge or 10 depth of discharge The Battery Full display is designed to show you State of Charge How the TriMetric determines that the batteries are charged We mentioned that ordinarily the meter automatically resets the amp hours to zero and therefore Battery full to full or 100 each time the battery is fully charged u
17. isplay allows you to set up the meter to remind you to fully charge the batteries after a certain number of days have passed You can set the number of days for example to 5 then when 5 days have passed since the TriMetric has sensed that the batteries have been fully charged the battery reminders lamp will blink and about every 12 seconds the numeric display will flash a Ch F It will continue the occasional reminder until you recharge the batteries or if you want to turn it off you can go the Days since Charged display and manually reset the Days since charged to 0 If you want to turn this reminder function permanently off you can program OFF into the number of days between reminders Another function of the battery reminders display can show you when the battery voltage gets too low When this occurs the battery reminders lamp will blink and about every 12 seconds B Lo will flash in the display You can set the desired low battery setpoint voltage or turn off this reminder if you like The third function of the battery reminders display is to remind you when to equalize the batteries Equalization will be described below in section C2 The TriMetric instructions describe in more detail how to set up these functions Optional How to measure total solar or other input amp hours As mentioned before the most common way to wire the TriMetric is to connect it to a shunt that measure
18. l loss of capacity Another purpose of equalization is to mix up the electrolyte in the battery which happens because of the gas bubbles that are produced when overcharging Of course just like overflowing a gas tank equalization does waste a little energy but if you don t occasionally equalize especially if your batteries are often not fully charged the batteries can gradually lose capacity Some charging systems have an automatic equalize function others have a manual switch Follow the procedure recommended by your installer dealer or battery manufacturer In some cases chargers do equalization automatically and no operator attention is required In other cases it involves changing a switch position on the controller to equalize for a specified amount of time or for a recommended number of amp hours overcharge More frequently however rather than keeping track of the number of amp hours overcharge a manufacturer may recommend that the voltage be raised to a fairly high voltage for a set period of time for example the Trojan battery company recommends 15 5V for 4 hours for a 12V battery system performed every month or two with charging at a rate of C 20 or less where C capacity of the battery system in amp hours After equalizing is usually recommended as the best time to check water levels and add additional amounts of distilled water if necessary Equalization generally causes the electrolyte level to rise slightly so adding at this
19. lead acid batteries sometimes called optimistically maintenance free The difference is that the former type has a battery cap for each cell which requires occasional addition of distilled water which the latter type does not hence the name maintenance free However it is a mistake to think that a maintenance free battery needs no maintenance at all If they are frequently overdischarged or over or undercharged they will give disappointing performance If you have the most common type of lead acid battery liquid electrolyte periodic maintenance must include occasionally checking water levels in the batteries However in trade for that disadvantage they have the advantage of lower cost and not being quite so particular about how they are charged If you have the maintenance free type of battery it is very important to adjust the battery charger voltage both generator charger and renewable energy charge controller carefully according to the battery manufacturer s instructions or your batteries could be damaged If you are not sure check with your dealer The TriMetric extra data function that measures maximum battery voltage can be used to check that the charging circuit is working correctly C Basic everyday TriMetric operation After you understand the information and terminology above you are ready to understand the specific suggestions that follow describing how to use the meter in everyday operation to utilize your ene
20. much energy is entering or leaving the batteries depending on whether they are being charged or discharged You can check that your solar array or other charging source is working properly and also become familiar with how much current your electrical loads are using which is important to know for conservation awareness Optional A shunt is used to measure amps With a battery monitor such as the TriMetric which measures very large amounts of current current amperes is measured by permanently wiring a shunt which is like a wire with an precisely known resistance near the batteries at the point where you want to measure the amps usually right into the negative terminal output connection from the batteries The TriMetric measures all the current that flows through the shunt The reason it is connected near the batteries is that the battery power wires must be kept quite short to avoid electrical losses because they carry such high current often over 100 amps Small sensing wires connect from the shunt to the TriMetric which converts a very small voltage to a current reading that the TriMetric displays as amps which you read on the display For example when using the 500 Amp 50 mV shunt called the H shunt one amp flowing through the shunt will result in one ten thousandth of a volt across the shunt which is measured and displayed by the TriMetric as 1 amp Although it is easily possible to set up the TriMetric to measure amps at other points in
21. n charge or amp hours Watts depend on the product of volts and amps entering and leaving the battery But the number of volts depends to a great extent on how fast the charging or discharging is taking place as well as temperature Therefore the energy you put in with charging is greater if you charge fast resulting in higher volts even when the amp hours delivered and the battery chemical change is the same Also lower temperature results in a greater difference between charging voltage and discharging voltage The chemical change in the battery however is dependent quite directly on the charge amp hours transferred When the batteries are being charged but before they have reached a nearly full charge and not gassing almost all of the amp hours go into direct chemical conversion which is almost completely reversible on discharge 96 or higher is common for lead acid chemistry when they are not at top of charge Similarly for a battery at the same chemical state at full charge the total energy you get out upon discharge is greater if the discharge is at lower amps since the resulting volts at the load will be higher during discharge Also this is why batteries are usually rated by amp hours not watt hours A few comments on lead acid batteries There are two subtypes of lead acid batteries of which the most common is the standard liquid electrolyte type The other type is the VRLA valve regulated
22. n appliance is the quantity of electricity used amps times the time that it is on hours Energy conservation awareness includes knowing about the electrical loads that may take little power but are on all the time sometimes called phantom or ghost loads These can take a lot of energy in a day For example a remote controlled TV usually takes some power when off to keep the remote control circuitry active Answering machines or chargers like electric toothbrush or other small tool chargers that use those wall plug cubes usually take a little power all the time The inverter that converts your battery power to ac power will take a small amount of power when it has minimum loads on it Use the TriMetric to monitor the current in amps with all lights and regular appliances off Multiply by 24 hours to find out the amp hours per day Compare this number with your total amp hour production in a day to see what percentage this is If you discover it is too high you may want to switch them completely off or take other measures to decrease their consumption Check that all appliances are really off when going to bed at the end of the day or when leaving the house Glance at the amps display to see that it is at its expected minimum level C2 Using the monitor to properly care for batteries Most owners of energy systems use lead acid batteries and this section assumes you are using lead acid batteries If you have another type of b
23. n so it will not be of as much interest to the casual user of the electrical system as it would be to a technician trying to check out an energy system The following table shows what happens to battery volts with lead acid batteries under some conditions of use For Wet Cell Lead Acid Batteries VOLTS 2 Volt system Battery overcharged or during final stage of equalize charge over 15 0 Battery near full while charging depends on amps 14 4 15 0 and temp Battery near empty while charging depends on amps and temp 12 3 13 2 Battery full with light loads depends on amps and temp 12 4 12 7 24 V system over 30 0 28 8 30 0 24 6 26 4 24 8 25 4 23 0 25 0 25 4 25 0 24 4 23 8 23 2 Battery full with heavy loads depends on amps and temp 11 5 12 5 12 7 12 5 12 2 11 9 11 6 11 4 22 8 10 5 11 5 21 0 23 0 Table notes When a range of voltages is shown in this table the voltage will be higher when more current goes in the battery charging and lower as more current leaves the battery discharging In addition the temperature affects the voltage as follows while charging a lower temperature will increase the voltage For example while charging a 12 V lead acid battery the voltage rises approximately 0 9 volts from 77 F to 32 F While discharging a higher temperature will increase the voltage There is little temperature effect while the battery is standing being neither charged or discharged Table 1 As can
24. nd although it can be easily stored in batteries for a short time on the order of days within the limitation of that storage it must be used as it is produced Generator is useful to fill in the gaps These last two disadvantages can be significantly overcome by using a petroleum powered gasoline propane or diesel generator to supply power for the occasional high load and to make up for periods of extended cloudy weather that would limit solar production However it is generally an important objective to minimize the time that a generator is running to minimize the noise pollution and higher cost per kW hr of the generator compared with solar energy production As will be explained below in section C 3 a system monitor that measures amp hours is a very useful tool to plan generator charging to minimize generator run time More user knowledge needed If you use grid power you don t need to know much more than the location of the switch and occasionally how to flip a circuit breaker and the location of your checkbook when the electrical bill arrives A renewable energy system even though often more reliable than grid power needs a user that has minimal knowledge about battery care and other system maintenance as well as more awareness of energy usage and conservation A system monitor is useful to help supply this kind of information and increase user awareness of their system as well as helping to locate the occasional problem Incidentally f
25. nless this feature is programmed off The question is how does the TriMetric determine that the battery is charged After the discussion of battery volts it shouldn t be surprising that it senses the battery voltage and also current As was mentioned before when batteries are charged the voltage on the battery set gradually rises At the same time the charging current amps usually declines The TriMetric measures both amps and voltage and when the voltage exceeds the programmed voltage setpoint adjustable by the user often set to 14 4 volts in 12 V systems double for 24V systems and the amps is less than the current setpoint which you may adjust the meter assumes that the battery is charged The current setpoint in amps is ordinarily set from C 50 to C 20 where C battery capacity in amp hours After this point is reached the meter announces this by flashing the charging lamp When the batteries again begin to discharge the meter resets amp hours to zero and resets the Battery Full to Ful At this time the Days since Charged display an extra display shown at the bottom of the front panel is also reset to 0 00 days From this point as the batteries are discharged and charged the meter tracks the amount that goes in and out of the battery bank like an accountant and shows the balance as the number of amp hours away from full charge and hence the Battery full This is a pretty good way to
26. or maximum usefulness the battery system monitor should be located where the occupants of the living area can glance at it easily for example the kitchen not in a garage or distant battery room B Basic TriMetric measurements and terminology volts amps battery full and amp hours Definition of battery capacity and battery state of charge A little information on lead acid batteries The purpose of this section is to familiarize you with the basic TriMetric measurements and to help you become familiar with some other background useful to understanding the basics of your energy system How to access the measurements on the TriMetric TM 2020 Successively pushing the SELECT button on the TriMetric switches the reading from volts to amps and then Battery full Pushing SELECT again puts the meter into the blank display Pushing SELECT again cycles back to volts again In addition five extra data functions shown on the bottom of the front panel which are used more occasionally are available by holding the SELECT button down for 3 seconds while viewing any of the above until AH appears in the display Releasing the SELECT button will now show the Amp hours from full display which will periodically alternate with AH This is the first of the extra data functions shown on the bottom part of the front panel The rest of these are accessed by now pushing the SELECT button
27. p hours of the battery is the total amount of electricity or charge that the battery can hold If you use the A hr from full display you will need to know what the capacity of your battery system is in amp hours to use the amp hour display to determine when your batteries are fully discharged If you don t know this value ask an energy system expert or dealer Eventually a section in Part 2 of this guide will describe how to determine it When the amp hour negative number equals the battery capacity you are out of power However the amp hour display is not ordinarily used to determine that you are completely out of power the volt reading is more useful for that Its value is to let you know about how much energy you have left well before your batteries are completely depleted so you can plan your electrical usage so you don t normally get to the point of over discharging the battery set The Battery full display is similar to amp hours from full except that it already incorporates the battery capacity information It reads Ful or 100 when the amp hour reading is 0 00 and reads LO or 0 when the minus amp hour reading equals or exceeds the entered battery capacity You will need to program in the correct capacity of your batteries into the TriMetric for this function to read correctly The Amp hours or Battery full information is also very useful to plan generator usage to minimize runnin
28. rge of the batteries If you use the amp hour from full display you ll need to know what your battery capacity is in amp hours Once you become used to your system and your normal electrical usage you will only occasionally need to refer to the meter This rule should encourage you not to always wait until the inverter cuts off your power because the system voltage is too low and then charge Lead acid Battery rule 2 If they do become discharged recharge as soon as possible If you do slip below 50 state of charge it isn t going to hurt very much if you get them up to full charge again soon If they become completely discharged don t allow them to remain in this state for long certainly not over 24 hours When the batteries are where they should normally be above 50 state of charge the battery volts is not usually a reliable indicator of state of charge However when the batteries are getting way too low in charge the volts reading is a good indicator tell you that this is happening The Battery reminders function will also flash a warning b LO if the battery voltage goes below the desired minimum battery voltage which you can choose and program in to the TriMetric When battery voltage goes below 11 0 11 2 12 volt systems or 22 0 22 4 in 24 volt systems volts the batteries are becoming more discharged than they normally should By this time you should have been prewarned before by the amp hour reading get
29. rge the next day Then when the batteries are at a low point such as later in the evening or early morning an hour or more before significant sun charge them with the generator until the amp hours on the TriMetric shows a value smaller than the amount your solar array will be able to produce the next day You can get double benefit if you choose a generator run time when you are using higher than normal loads so while the generator is charging it can also supply power to these loads rather than using battery power that will later need to be replaced by further generator run time There are two 14 benefits to this method you will run the generator quite a bit less this way and it will give your batteries a better charge because they spend more time at low charging current at the end Example if you know you can charge 100 amp hours per sunny day with the solar array and you expect sun tomorrow if the amp hour number on the TriMetric is down to 130 amp hours turn on the generator to charge until you are down to 80 when the solar modules start producing The solar modules the next day should fully charge the batteries which can be confirmed later that day by checking the days since recharged display If you can also manage to schedule the generator while you are using heavier than average loads further generator time will be avoided because not as much battery recharge will need to take place Optional information about charging ra
30. rgy system better The three topics to be covered in section C are C1 Using the TriMetric for energy conservation C2 Using the TriMetric to properly care for batteries C3 Using the TriMetric to minimize generator usage Numbers you need to know To make best use of your monitor you must be sure you know some important numbers related to your system If you are not sure how to determine them yourself ask someone who is qualified to get these numbers Battery capacity of the system is about ___ amp hours If you don t know how to determine this ask your dealer or other energy system expert This number should be entered into the TriMetric as the battery capacity as described in the TriMetric instructions for the Battery full display to read correctly Generator charging amps may vary with battery voltage so check it at a nominal voltage between 13 and 14 for 12 volt systems or 26 28 for 24 volt systems Note the approximate voltage as well as the amps amps at volts The charging current often goes down as the voltage increases Solar charging amps Obviously will vary with time of day so check when sun is about maximum It may also decrease as temperature rises so note the temperature Higher battery voltage may also decrease charging current so note battery voltage for reference Charging current is DECSS volts Outside temperature ___ Normal charging amps of any other charging sources Approximate energy prod
31. s are always full could 11 make the system more costly than necessary by providing more generating capacity than really required and also make the system less efficient because if the system is already full it would not be able to store an extra energy windfall if a temporary period of lower usage or higher energy generation becomes available Battery safety Batteries can be dangerous They should always be inaccessible to children If a metal tool or other conductor shorts across battery terminals it can instantly get very hot and cause a fire or burns Remove metal rings while working with batteries which if they short across battery terminals will cause severe burns Although rare batteries can explode from hydrogen and oxygen gas inside the batteries and spray acid everywhere Or when adding water some acid could accidentally splash and hit eyes Use safety goggles to protect eyes from this possibility Purchase a pair of goggles and store them in the vicinity of the batteries so they are handy to use when working around them Lead acid Battery Rule 1 Usually keep them above 50 state of charge The general idea is to keep your batteries toward the top of their charge rather than toward the bottom And if you need to use the generator to do this don t wait until they are all the way to the bottom before turning on the generator Use the Battery Full or amp hour from full display to keep yourself informed about the state of cha
32. s entirety Any partial use or distribution in any other manner must be by written permission only Bogart Engineering Ralph Hiesey 19020 Two Bar Road Boulder Creek CA 95006 831 338 0616 Table of contents Part 1 A Renewable energy systems Practical now A few remarks about renewable energy systems that use batteries for electrical storage B Basic meter measurements and other terminology Terms you should be familiar with before reading the next sections including volts amps amp hours efficiency factor battery capacity B1 Using amps B2 Use of volts Includes table showing meaning of voltage readings for lead acid batteries B3 Using Ampere hours Capacity Charge efficiency factor State of Charge How the TriMetric detemies that battereies are charged Some comments on lead acid batteries C Basic everyday TriMetric Operation Conserving energy taking care of batteries deciding when to run generator Everyday practical use of the TriMetric with lead acid battery systems on a properly operating energy system for other than lead acid see also section 6 C1 Using the TriMetric for energy conservation C2 Using the TriMetric to properly care for batteries Four rules for battery care C3 Using the TriMetric to minimize generator usage How batteries absorb energy How not to use a generator Strategy for efficient generator use Part 2 To be completed later A Renewable energy systems are practical now
33. s is not a serious limitation It is even practical to run some heat producing appliances provided they don t run too long such as microwave ovens toasters or hair dryers However it is important to be mindful of electrical usage a battery system monitor such as the TriMetric that shows amps of current draw from the system is very useful to increase user awareness of energy consumption You need a site that has solar wind or hydroelectric energy available Not every site has a suitable source of energy If solar energy is available energy from photovoltaic panels is usually the cheapest and most reliable Hydro power or wind power is also possible for those sites that have sufficient wind or a stream available May not supply extremely high power The grid can easily supply either a little power or very much power however a renewable energy system of reasonable cost is somewhat limited in its ability to supply maximum energy demand You can easily power a toaster for a few minutes but you may not be able to run your washing machine and microwave at the same time unless you have a larger system however these larger systems are becoming more common so that now this may not be a practical limitation Power needs to be used within a week of the time it is produced With grid power you can choose to use a little power in one month and a lot of power the next month A renewable energy system usually has a certain amount that is delivered every day a
34. s net current in or out of the battery Some people may want to use the TriMetric to measure only the total solar or wind input amp hours from their source to measure for example daily solar production This can be done by wiring a shunt in series with solar or other input wire on the negative side so that only the desired current to be measured passes through the shunt The amp hour display will then record the total input amp hours and amps In this case the efficiency factor should be set to 100 and the automatic reset of amp hours should be programmed off It s also possible to arrange a switch to connect the TriMetric to either one shunt or the other Then you can switch from net battery current to just input energy so occasionally throughout the year you can temporarily switch to check the solar or wind input for a day to check out total daily energy production However you ll then lose track of battery amp hours until you switch back and resynchronize with the batteries again by fully charging them Or of course you can wire two TriMetrics and have both all the time Optional technical note Why measure amp hours not energy Some people familiar with physics or engineering principles may ask why amp hours are used to keep track of energy in the battery Why not use energy directly which is watt hours The answer to this is that for batteries watt hours is a less stable measure of battery electrical content tha
35. te One traditional rule for lead acid batteries is the ampere hour rule that a lead acid battery can absorb amps at a rate in amps equal to number of amp hours away from full charge In other words the number of amps while charging shown on the TriMetric should be equal or less than the number of amp hours shown on the TriMetric The implication of this rule is that although the current can start out very high at low state of charge when the amp hour number is a large negative value it must gradually taper down to 0 at the end of charge to spend more time at the end This rule is probably most applicable to auto batteries which are designed for high currents so for the type of deep cycle batteries used in renewable energy systems it is probably best to limit charging current in amps to 50 or less of the value of amp hours left in the battery bank Example if the meter shows 100 amp hours the batteries can absorb 50 of 100 or 50 amps of charging current at that time As charging continues the charging rate must decrease for the batteries to fully absorb the charging current 15
36. the circuit to measure only solar array current or only load current with renewable energy systems it is usually set up to measure the net amps into or out of the battery by inserting the shunt in the negative terminal from the battery so all the current flowing in or out of the battery is measured Often called net battery current Set up in this way the TriMetric can also use the Batt Full or amp hours displays to show how full the battery is as will be explained more fully later 2 Use of volts The second of the three main numbers that the TriMetric battery monitor measures is volts across the battery or electrical potential or electromotive force e m f of the battery This is a measure of the force with which the electricity is pushed by an electrical source such as a battery solar array or generator into an electrical load Not surprisingly in almost all cases if the amount of force or number of volts increases from the source the amperes or flow through the load will increase because the force behind the electricity has increased It is useful to measure volts because it is a basic electrical measure of the battery or the solar array or charger It s like measuring pulse or blood pressure and is especially useful as a diagnostic tool especially when used in conjunction with an amps measurement However it requires more understanding and interpretation than either amps or amp hours to provide useful informatio
37. ting below 50 charge point And if not the battery capacity may be getting lower than expected due to age or past mistreatment or they simply may be colder than normal The volts reading is the authoritative indicator that the battery is at or near discharge for example if the battery system has lost capacity because they are old or have suffered abuse or perhaps because they are colder than normal resulting in temporary lower capacity until rewarmed again If you discover that the voltage has become excessively low when the amp hour reading would indicate that some energy is left you may want to recalibrate your battery capacity estimate for the future or check your batteries or the connections to see if something is wrong Incidentally the minimum volts data function of the TriMetric the d 6 function can be used to check how low the voltage has gone while you are away or during some period in which you do not wish to constantly monitor the volts reading on the meter Lead acid Battery Rule 3 Fully charge every week or so Every week or more often you should charge the batteries sufficiently for the TriMetric to reach the charged setpoint 12 which is both good for the batteries and it will also resynchronize the TriMetric Battery full and amp hours from full display with the batteries You can observe how long ago the batteries were fully charged by examining the days since charged display In ad
38. ts an efficiency factor of 96 Lead acid batteries are quite charge efficient and for these this number is pretty high typically 94 98 and we recommend if you have new lead acid batteries to set it to 94 as a good approximation Setting it to 94 is usually conservative which should cause the meter to err slightly on the side of indicating a little less energy than you really have Optional note for the technophile on efficiency Some people are surprised that the charge efficiency factor should be so high at 94 98 There are two reasons for this One reason is that Energy efficiency which is often quoted for lead acid batteries at 75 85 is frequently confused with charge efficiency which we are talking about here Charge efficiency of a battery is the ratio of amp hours required to charge a battery compared to the amp hours that can be removed later In contrast energy efficiency of a battery is the ratio of the amount of total energy required to charge the battery compared with the amount of energy you get out when discharging Energy volts x amps x time Energy is measured in watt hours or joules which is the same as a watt second Energy depends not only on amp hours but also takes into account that you don t get as high a voltage out when discharging a battery compared to the voltage required to charge the battery This is why the energy efficiency is less than the charge efficiency The other reason that the charge effic
39. uction amp hours in one sunny day Summer __ Winter ___ Of course this depends on the season so it is good to know the extremes The 10 approximate total solar production per day is useful to know for minimizing generator usage as described below C1 Using the TriMetric for energy conservation Be knowledgeable about how much energy your appliances use Use the AMP reading to familiarize yourself about how much power various electrical loads use on your system First turn the appliance off and note the amp reading Then turn it on to find out how many more amps are being used The difference in the two readings is the amount the appliance takes You might want to write down some of these numbers when you first use your TriMetric You can think in terms of amps or if you prefer watts by multiplying the amps reading by 12 or 24 depending on your system voltage The important thing is to develop an intuition about the relative amounts of energy required by different items for example you might discover that your outside lights take approximately 3 times the energy of the inside living room lamp After a short time you will develop some instinct for the electrical usage just like you might know about how much the bananas in the store are going to cost before you look at the price This awareness will help the users of the system to conserve energy Watch those 24 hour per day ghost loads The total electrical usage amp hours of a
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