Kit Instructions
Contents
1. 1 800 831 4242 www Jameco com Car Battery charging system diagnostics PART NO 2192106 You can hook up the kit s test leads directly to the car battery with engine off and see whether battery voltage is ok green LED on or low yellow LED on Actual testing begins when you start the car The starter draws a lot of current so while cranking the yellow LED should come on indicating that voltage is low but still good If the red LED comes on while cranking and or does not start at all this indicates that battery may need recharging or the battery needs to be replaced if the red LED still comes on after recharging Once the engine starts the green LED should start blinking for half a second on and half a second off This indicates that the alternator is charging the battery While the engine runs idle you can turn head lights on A C on radio on windshield wipers on etc and green LED should continue blinking indicating that alternator is charging the battery properly Run the engine at about 2000 rpm with the above mentioned loads on and green LED should continue blinking In the event red LED starts blinking this indicates that battery is being overcharged which could damage the battery and corrective action should be taken Only one LED comes on at any given time which makes it easy to interpret the results Time Required 1 hour depending on experience Experience Level Intermediate Required tools and2. because the starter motor draws the greatest current the battery will ever supply compared to the other loads While engine is cranking and if red LED ever comes on this means your battery is either under charged or your battery is bad If your starter just clicks or the engine is cranking too slowly and does not start have the battery recharged Once battery has been recharged repeat the test If engine starts but red LED still comes on while cranking replace the battery For inexperienced individuals While performing this initial test through the cigarette lighter adapter there may not be any voltage with engine off unless the key is turned to ACC position Also most cars we have tested through cigarette lighter adapter do not supply any voltage while cranking the engine therefore the battery monitor lights will go out and will not come on until engine starts The following tests work with both types of test probes Voltage drop tests should be performed by professional mechanics Charging Voltage When engine is idle green LED should be blinking at the rate mentioned above This means battery voltage is at least 13 1V and green LED will blink while battery voltage is equal to or greater than 13 1V and less than 15 4V For a charging test while engine is idle turn on your A C radio windshield wipers headlights etc Once these loads are on green LED should still be blinking which means your alternator can maintain charging voltag
3. parts 1 Soldering iron and solder 1 Clip on heat sink Jameco P N 159126 1 Needle nose pliers 1 Diagonal cut pliers 1 Automobile Fused Power Plugs with cords Jameco P N 124760 2 Connector Power PL 2 Position straight cable mount Jameco P N 191484 6 feet cable 18 AWG 1 Pair alligator clips one red one black Jameco P N 70991 1 1 oz tic tac empty box Bill of Materials 691104 10K 1 4W resistor 5 R1 R6 R7 690988 3 3K 1 4W resistor 5 R2 690742 330 Ohm 1 4W resistor 5 R3 R4 R5 93739 22uF 50V Electrolytic 20 C1 198839 10uF 16V Electrolytic 20 C2 CO 1N4004 400 PRV 1A Green LED 5mm Yellow LED 5mm 697522 Red LED 5mm 51182 Standard Regulator 5 Volt 0 14 Amp 3 Pin TO 92 Box 765302 Preprogrammed MCU 8 bit ATtiny 51571 Socket IC 8 pin 8 Pin DIP IC Socket 101178 Jack DC Power Male 2 1 mm J1 Connector Jack DC Power male Step 1 Verify parts are complete Resistors 3 330 Ohm 1 4W 5 resistors R3 R4 R5 1 3 3K 1 4W 5 resistor R2 3 10K 1 4W 5 resistors R1 R6 R7 Capacitors 1 22uF 25V Electrolytic cap C1 2 10uF 16V Electrolytic cap C2 C3 Semiconductors 1 1N4004 400V 1A rectifier D1 1 Green LED 5mm LED1 1 Yellow LED 5mm LED2 1 Red LED 5mm LEDS 1 ATtiny 13 ATMEL microcontroller 1C1 1 78L05 5V regulator IC2 Miscellaneous 1 DC Jack Connector J1 1 8 pin IC socket 1 Printed Circuit Board Main Features Designed fo
4. place it into R2 Once these resistors are in place solder in their leads to their solder pads These resistors form a voltage divider that conditions battery input voltage to ATtiny 13 Analog to Digital converter Now locate three 330 Ohm 1 4 resistors and solder them in into R3 R4 and R5 positions These resistors are used as current limiters for LED1 LED2 and LEDS Last take the remaining two 10K 1 4 resistors and solder them in place in R6 and R7 positions The purpose of these resistors is to pull up unused inputs to 5V for proper operation of microcontroller Step 4 Add capacitors Place the 22uF capacitor C1 into its position one 10uF capacitor into C2 and the other 10uF capacitor into C3 positions and solder them in place Step 5 Install Semiconductors Using a clip on heat sink solder in diode D1 observing polarity mark Heat sink in picture is shown so heat is applied to this lead to reduce overheating the diode Allow a few seconds for D1 to cool off then move clip on heat sink to the other lead and do the same When soldering IC2 place the heat sink also on same lead that is to be soldered in and allow several seconds to cool off before moving on to next lead until you are done with all three leads Now if you want the body of each LED to be touching the PCB the heatsink won t fit between the body of LEDs and solder joint so you will have to be careful and solder each lead without heat sink as quickly as possib
5. 00 rpm Green LED should be blinking If Red LED starts blinking this means alternator is overcharging battery which could be caused by a faulty voltage regulator With engine running at 2000 rpm voltage across battery terminals should be no higher than 15 4V If voltage is 15 5V or higher battery is getting overcharged This may be due to a bad charging system Simplified Software Flowchart Voltage Regulator ATtiny 13 to ADCO3 which reads 751 PB4 PB1 PB2 330 330 330 LED3 LED2 LED1 ja Ny Red ellow iGreen When battery voltage is 15 5V or higher red LED starts blinking half a second on and half a second off The Schematic Diagram Battery voltage gets into the battery monitor through connector J1 Diode D1 is used to protect the entire circuit against accidental battery polarity reversal in case you decide to test the battery directly across its terminals in the engine compartment Should you connect the test alligator clips reversed nothing will happen IC2 is a 5V low dropout voltage regulator Its input voltage range with a 100mA load varies between 5 4V up to its absolute maximum of 30V admit that for this battery monitor a 78L05 5V voltage regulator would have been more than enough however had no 78L05s and several LP2950CZA 5 0 kicking around in my junk box Capacitors C1 and C2 22uF and 1uF are voltage regulator s input and output filters If you want to use pin compatible 78L0
6. 5 voltage regulator instead use a 10uF capacitor as C2 The battery voltage feeds both the voltage regulator and the ADC input circuit to ATtiny through a voltage divider formed by a 10K resistor and a 3 3K resistor marked as R1 and R2 respectively This voltage divider is used to reduce battery voltage to a safe input voltage range between OV and 5V for Altiny s analog input This voltage divider allows a maximum car battery voltage of 20 8V for this input voltage range In order to smooth out this analog input voltage a 10uF C3 is used to reduce noise The visual output to the user is shown by means of three LEDs A Red LED LEDS3 shows either too low a voltage or a dangerous overvoltage A Yellow LED LED2 shows a moderate low voltage and the green LED LED1 shows good voltage and safe charging voltage Each LED comes with its respective current limiter 330 Ohm resistors R3 R4 and R5 Resistors R6 and R7 at 10K each are pull up resistors for unused inputs Step 2 Schematic Diagram See all components listed in bill of materials and how they are wired together to form the battery monitor J hey N 40UT TE AINAT GND VEC PBO PCINTOAINVOCUAMOs ale PBT PCINTIAINTOCUBINTOMISO mmi PBXPCINTZVSCKADCITI PES PCINTACLKVADCS PRA PCINTAADE 2 PBS PCINTSRESET ADCODW GND TINY 13 20PU Step 3 Solder in resistors Start by locating a 10K 1 4 resistor and insert it into R1 position Take the only 3 3K 1 4 resistor and
7. ED would still be on which means the software would still be running It was then that in order to prevent further problems unused pins 1 and 5 were pulled up to 5V through 10K resistors ATtiny 13 code This sketch monitors battery voltage and turns on an LED based on it Processor ATtiny 13 Author rlarios Date 13 04 03 int rLED 4 Red LED pin int yLED 1 Yellow LED pin int gLED 2 Green LED pin int val 0 This variable will hold voltage input value int dlyctr 0 This is the delay counter void setup pinMode rLED OUTPUT Define Red LED output pinMode yLED OUTPUT ditto Yellow LED pinMode gLED OUTPUT ditto Green LED void loop val analogRead A3 Read voltage through Analog input 3 if val lt 452 Is battery voltage below 9 6V digitalWrite rLED HIGH Yes this is bad turn on Red LED digitalWrite yLED LOW Turn off Yellow LED digitalWrite gLED LOW Turn off Green LED else if val lt 594 Is battery voltage between 9 6V and 12 4V digitalWrite rLED LOW This is a low voltage turn off red LED digitalWrite yLED HIGH Turn on Yelow LED as a warning digitalWrite gLED LOW Turn off Green LED else if val lt 629 Is battery voltage between 12 4V and 13 1V while idle digitalWrite rLED LOW Yes turn off Red LED digitalWrite yLED LOW Turn off Yellow LED digitalWrite gLED HIGH Turn on Green LED t
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9. attery place red alligator clip on battery s positive terminal and black lead on negative Using a multimeter set on DC Voltage measure volts between U1 leads 4 and 8 Place multimeter s black test lead on terminal 4 Gnd of U1 and red test lead on terminal 8 Vcc Voltage reading should be 5V as shown on attached picture 5 05V After completing this test it s time to disconnect battery and prepare battery monitor for final test Step 9 Final Test Final Test Insert pre programmed ATtiny 13 MCU into U1 socket making sure IC is properly oriented using index mark as a reference Now put in assembled battery monitor inside an empty Tic Tac 1 oz box with LEDs side first in Slide test probe plug through hole of Tic Tac box lid and plug it in into DC power jack of PCB Put lid in place KKK Disclaimer Car batteries can hold a huge amount of charge Only trained car professional mechanics or experienced individuals should try testing directly on car battery terminals Doing the following procedure across battery terminals is the sole responsibility of individual performing the tests The following procedures should be performed as described being extremely careful not to short circuit battery terminals together by any means Failure to do so due to negligence carelessness etc may produce bodily injuries or death In order to reduce risks individuals not experienced working inside car engine compartments must use automobile Fu
10. e in spite of these loads drawing current If green LED stops blinking and stays fully on while this is going on have a professional mechanic check your battery terminals for excessive voltage drop with a multi meter A voltage drop higher than 0 1V would be considered excessive and should be corrected If voltage drop is about right and green LED remains on without blinking measure the voltage with a good voltmeter so a reading of at least 13 1V should be obtained If voltage is right chances are the difference may be due to tolerance of components in your battery monitor If voltage is less than 13 1V and no significant voltage drop is found then have your charging system checked by a professional Chances are you have a bad alternator Charging Voltage at 2 000 rom Have same loads as above turned on and run the engine to at least 2 000 rom Green LED should remain blinking In the event red LED starts blinking at same rate given above your alternator is overcharging your battery This means that the system voltage regulator is not working properly Again have your system checked by a professional O D Ge 5 3 ZCosegs 1495 J BATERIA AUTOMATA The Software The software was written based on the hints given by Eric the car guy in this excellent video He didn t mention the voltage at which a battery can be considered bad However my own car s service manual stated that while cranking the engine voltage should not get lowe
11. le Solder joint has to be done properly though Insert green LED into LED1 position watching that cathode the shorter lead is facing to the edge of PCB and solder in place Yellow LED goes into LED2 position and red LED into LED3 position All cathodes facing towards the edge of PCB Step 6 Install IC socket and DC Jack Power connector Put 8 pin IC socket into U1 position making sure that index mark is properly oriented and solder in place Be careful not to solder two adjacent pins together If this happens reheat with soldering iron and when solder melts wipe excess solder away Make sure that pins are properly soldered Now this part proved to be tricky J1 connector comes with wide leads which called for oversized holes in the PCB Place DC Jack power connector into J1 position making sure when PCB is with solder side up that connector does not fall off PCB Get soldering iron and solder close to first solder joint you are about to make Melt some solder on soldering iron tip making sure that the solder bead formed this way is slightly bigger than the space between J1 connector lead and its solder pad then apply this solder to this solder joint making sure that solder stays in place and does not flow through the hole into component side of PCB Repeat for the remaining two leads of J1 connector This completes assembly of this kit Step 7 Assemble test probes Grab one of the connectors Jameco P N 191484 and solder at least tw
12. o feet of 18 AWG cable to each one of the two terminals as shown in the picture The picture shows one red and one black segment soldered in into the connector s terminals Your cable may be one color only Grab the two alligator clips Jameco P N 70991 and solder in the red one to the other end of the wire soldered to the central terminal of connector P N 191484 Now solder in the black alligator clip to the other wire the one whose other end is soldered to the edge terminal of same P N 191484 connector Make sure that both terminals are not touching each other before putting the cover back on this connector Automobile Fused power plug Jameco P N 124760 comes with a two wire cable whose ends are stripped Using an Ohm meter check continuity between the center terminal of this cigarette lighter connector and the two ends to find out which one is connected to it Once center terminal s wire is located solder it in into the center terminal of the second PL 2 position connector Jameco P N 191484 Solder in the remaining cable end to the edge terminal of same connector Jameco P N 191484 making sure both terminals don t touch to each other before putting the cover back on this connector Step 8 Test Battery monitor Power supply Before inserting ATtiny micro controller into its IC socket let s make sure first that onboard power supply is working properly Plug in the test probes assembled in previous step into onboard DC Power Jack With a 9V b
13. o indicate fully charged battery voltage else dlyctr dlyctr 1 increase delay counter every pass approx 100ms if val lt 751 Is battery voltage above 13 1V and below 15 5V digitalWrite rLED LOW Turn off red LED digitalWrite yLED LOW Turn off yellow LED if dlyctr lt 6 digitalWrite g_LED HIGH Pulse green LED on for half a second else digitalWrite gLED LOW Pulse green LED off for half a second to show battery is charging if dlyctr gt 10 dlyctr 0 Reset delay counter else Battery voltage is above 15 5V Danger Overcharge digitalWrite yLED LOW Turn off Yellow LED digitalWrite gLED LOW Turn off Green LED if dlyctr lt 6 digitalWrite rLED HIGH Turn on Red LED for half a second else digitalWrite rLED LOW Turn off Red LED for half a second if dlyctr gt 10 dlyctr 0 Reset delay counter delay 100 Stop program 100 milliseconds to help pulse LEDs e ee int EMED di Imt Wi jI int lH 2 ht Tal if PLC By void orig Bini CSTR poi tpl Te piace dell COTA idi lepih eed ged ee ep LEAR gush yl Aah Spel Pricagyl Lops glial Pelle Gp I i EE jvais pidi i Programming ATtiny 13 You ll have to wire Arduino UNO and ATtiny 13 as shown in one of the images in this step Make sure ATtiny 13 pin 1 is properly oriented Once wiring is ready you ll have to load Arduino IDE in your lap
14. r 12V car battery electrical systems e Easy to program through Arduino e Simple 8 pin IC microcontroller e Compact fits inside an empty Tic Tac 102 box e Can test battery in engine compartment e Can monitor battery status through cigarette lighter receptacle e Protection against polarity reversal Inexpensive Car Battery Monitor Block Diagram Voltage Regulator ATtiny 13 ATtiny Analog to Digital Conversion process The ADC converts an Analog input voltage to a 10 bit digital value through Successive Approximation The minimum value 0 represents GND potential 0V and the maximum value 1023 represents Vee 5V Vade From straight line equation Vee 5V Vade Vadet m d d1 ussssssssssssseans 1 Vade Vade1 5 0 m E gt au d di 1023 0 Plugging values of m and 1023 5 into 1 d 8d2 4923 d digital value read by Vee ATtiny s ADC within this ov d OV SV range Vec 5V ATMEL Altiny 13 Pinout of ATtiny 13A 8 PDIP SOIC PCINTS RESET ADCO dW PBS C 1 8 D Vcc PCINT3 CLKI ADC3 PB3 C 2 7 2 PB2 SCK ADC1 TO PCINT2 PCINT4 ADC2 PB4 LJ 3 6 LJ PB1 MISO AIN1 OCOB INTO PCINT 1 GND LJ 4 5 C PBO MOSI AINO OCOA PCINTO Analog input Voltage conditioning circuit Vbatt Vd to Voltage Regulator input R2 Vade Vbatt Vd TRi Ra Battery voltage has to be conditioned so ATtiny 13 s Analog to Digital Converter input can read it without exceeding its maxim
15. r than 9 6V If it does then battery should be replaced which seems to be about right for most car batteries This sketch is very simple just a series of consecutive IF instructions to compare voltage read through ADC3 with some predefined values If you follow the code closely you ll see that the values shown in the Theory of Operation slide show in Step 1 are the same values used in the different IF instructions to decide which LED should come on To create the blinking effect on LEDs whenever voltages are higher than 13 1V a counter is increased by one on every pass through that portion of the code Before the code loops back to read ADCS again execution is delayed 100 milliseconds IF instructions turn LEDs on whenever the pass counter is below 6 and turn LEDs off whenever counter is between 6 and 11 Once counter reaches 11 the counter is reset to zero to repeat the cycle ADC3 input is used to read the analog voltage coming from the voltage divider By the way ADCO had been the first choice as this project s analog input however when voltage coming from the battery was a bit lower than 8 7V all three LEDs would go out This didn t seem right as had used a low dropout voltage regulator After doing some more research on the web found that anytime you used a pin as an input that could also function as hardware Reset these things could happen Once ADC3 was selected as analog input battery voltage could come down close to 6V and red L
16. s than 12 4V yellow LED will come fully on If voltage falls below 9 6V yellow LED will go out and red LED will come fully on With engine running idle and most loads on battery voltage should be at least 13 1V This proves alternator is charging ory Voltage Regulator ATtiny 13 to ADC03 which reads 629 PB4 PBI PB2 330 330 330 LED3 LED2 LED1 hs N Red ellow Green When battery voltage is between 13 1V and 15 4V green LED blinks half a second on and half a second off Cranking engine test This battery monitor cannot test for Cold Cranking Amps so we ll start the engine instead While cranking only yellow LED should come on If red LED comes on briefly battery may be bad even if engine starts and green LED comes back on Either get your hands dirty or havea mechanic do a voltage drop test before dooming battery Once engine started Green LED should be blinking on and off If it does not blink or worse yellow light comes on alternator may be bad With green LED blinking turn on A C radio headlights etc except rear defogger Green LED should remain blinking on and off which proves alternator is doing its job If Green LED stays on without blinking get your hands dirty or have a mechanic do a voltage drop test between battery and alternator Overcharge test Turn on A C radio headlights windshield wiper etc except rear defogger Run the engine to at least 2 0
17. sed Power plug for testing battery through cigarette lighter receptacle inside car instead KKK End of Disclaimer For trained car professional mechanics Pop up the hood of your car so you have access to the engine compartment With engine off hook up the black alligator clip to the negative battery terminal Now attach the red alligator clip to the positive battery terminal If battery voltage is Ok green LED should come on Green LED comes on and stays on no blinking when battery voltage is greater or equal to 12 4V and less than 13 1V When a battery is fully charged its voltage should be 12 6V but it may vary within the range given above Now make sure your battery monitor and its test probe wires cannot get in the way of moving engine parts Make sure parking brake is on and if your car has manual transmission it is set to neutral Most automatic cars will not even start if the transmission is not set to Parking Then have someone start the engine while you watch the monitor Watch battery monitor carefully as engine starts While engine is cranking a good battery should cause yellow LED to come on Once engine starts green LED would come on but now it will start blinking at a rate of about half a second on and half a second off approximately Yellow LED comes on only when voltage is greater than or equal to 9 6V and less than 12 4V As this is just a battery monitor you can consider this cranking voltage test as a load test
18. top computer and configure it so it can be used as a programmer won t get into the details here about configuring Arduino UNO as ISP and where to get ATtiny 13 s libraries After some research found this excellent video by Chris Stubbs on how to do just that The video also shows how to wire Arduino UNO and ATtiny 13 together After Arduino UNO is configured to function as ISP and ATtiny 13 libraries have been loaded it is time to select our target board From Arduino IDE menu bar click on Tools gt board gt ATtiny 13 9 6MHz internal 9 6MHz clock Next type in the battery monitor sketch into Arduino IDE and proceed to compile it and upload it into ATtiny 13 The selection of ATtiny 13 with a 9 6MHz clock will cause the blinking rate of LEDs to have a period of about 1 4 seconds This means LED will be on 0 7 seconds and off 0 7 seconds which is close to what originally intended We will put our Car Battery monitor together in the following steps CC MO M E Filise ana Toeh iuie Mom O N om O0 Tan sece i tomer Chews One amo N Dyis Mee s C3 daaag Saes O D 5 Ce oane e Upe et cm rea Upee nag Pengremmer cwe e M aoee CoP he is a p Wiring an Arduino UNO to program ATtiny 13 ow aQ bebat S Aileen Cages irea fone ae noes s ee x s ntm Ead ban E E E eee ere eve ee ere ervree vee i tort 0 Pie drt Sketch Help ATA B
19. um allowed input voltage 5V The voltage divider formed by R1 10K and R2 3 3K allows a maximum Battery voltage of Ri R2 Vbatt Vade R2 Vd Vbatt 20 85V Which means we are safe First test with engine off Visually inspect battery terminals for corrosion Check with your hands whether terminals are loose If everything above is correct hook up battery monitor across battery terminals Battery monitor will turn green LED on if battery voltage is between 12 4V and 13 1V If yellow LED comes on instead this means battery voltage is low A fully charged battery should have 12 6V across its terminals With engine off if voltage is between 12 4V and below 13 1V green LED should come fully on indicating normal battery voltage Voltage Regulator ATtiny 13 to ADC03 which reads 594 PB4 PBI PB2 330 330 330 LED3 LED2 LED1 Be Red ellow Green When battery voltage is between 12 4V and below 13 1V green LED will come fully on With engine off If battery voltage is below 12 4V yellow LED will come on showing a low voltage condition If engine does not start recharge battery While cranking engine A good battery would cause yellow LED to come on If red LED comes on even after battery has been recharged replace battery Voltage Regulator ATtiny 13 to ADC03 which reads 452 PB4 PBi PB2 330 LED3 V V Red When battery voltage is between 9 6V and les
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