# 12v Testing Method?



## LithiumaniacsEVRacing (Oct 9, 2010)

I have tested my Haiyin 400amp cells only to 100amps with my equipment, the factory claims they tested 400+amps per cell.

I have bought a basic automotive load tester (design for 12v batteries) that will pull 300amps, so I built a 1P 3S pack for testing. Will this work?


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## LithiumaniacsEVRacing (Oct 9, 2010)

If it works I will video tape the draw and the voltage drop, should be interesting? 

i know last year I started one of my diesel truck with a Turnigy nano tech pack, spun like hell!


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## Ziggythewiz (May 16, 2010)

What voltage are your cells? Usually a 12V battery would be replaced by 4 lithiums (at least of the LiFeP04 variety).


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## dougingraham (Jul 26, 2011)

3*3.7 (nominal voltage of those cells) = 11.1V Fully charged point would be 12.6V.

Seems like it should work. Will give you an idea of the sag at 300A anyway.

They should sag significantly less than a car battery. I will be interested to see what happens.


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## Tesseract (Sep 27, 2008)

LithiumaniacsEVRacing said:


> I have tested my Haiyin 400amp cells only to 100amps with my equipment, the factory claims they tested 400+amps per cell.
> 
> I have bought a basic automotive load tester (design for 12v batteries) that will pull 300amps, so I built a 1P 3S pack for testing. Will this work?


Probably. To measure the internal resistance of the cells - which is what you really want to know - you need to compare the voltage at two different currents, not at 0A and, say, 100A. This is so you don't get an inflated resistance figure from the surface charge. 

So, try measuring the voltage at, say, 100A then again at 200A. The difference in voltage divided by the difference in current (100A in this example) will give you the total resistance of the pack.

You can go one step further and use a digital multimeter to read the voltage across each cell while testing at the two currents which will help you sort out any outliers - ie, those cells with much higher or lower resistance.


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## LithiumaniacsEVRacing (Oct 9, 2010)

Tesseract said:


> Probably. To measure the internal resistance of the cells - which is what you really want to know - you need to compare the voltage at two different currents, not at 0A and, say, 100A. This is so you don't get an inflated resistance figure from the surface charge.
> 
> So, try measuring the voltage at, say, 100A then again at 200A. The difference in voltage divided by the difference in current (100A in this example) will give you the total resistance of the pack.
> 
> You can go one step further and use a digital multimeter to read the voltage across each cell while testing at the two currents which will help you sort out any outliers - ie, those cells with much higher or lower resistance.


This test is very late, my packs are built, but will give me a max draw point on these cells. Jeff, I will do what you recommended. I will complete tests at 100amps watch how long cells hold till lowest, then 200amps, then 400amps. The cells were tested in China up to 100C (they say) so 400amps should hold. 
I will be very satisfied with 300 to 400amps per cell, will work for Shiva's at 10P. I will press the issue and test till they go BOOM! In an enclosed lexan box, just want to see the cells max point before the Lipo fireball!


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## LithiumaniacsEVRacing (Oct 9, 2010)

*My 12v 400amp MONSTER!*









*Video Soon!*


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## Ziggythewiz (May 16, 2010)

Oh good, that's the charger. I saw the leads and thought you were going to pull 400 Sam's Club amps.


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## LithiumaniacsEVRacing (Oct 9, 2010)

Tested a 4S pack of my Haiyin cells at 300amps for 15 seconds.
Starting voltage 15.69v, after the 15 second 300amp draw final pack voltage 15.24. Seems like a 2.85% drop. 

Update,the actual time was 17 seconds of amps draw, I used a timer while watching video.

http://youtu.be/AuzxsPP-j7E


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## LithiumaniacsEVRacing (Oct 9, 2010)

Tested a 3S pack to record voltages.

http://youtu.be/Y9vPVLwB50U

Start 12.18V
200amps 9.91V
250amps 9.63V
300amps 9.42V

This test was timed on the video, the total time drawing amps was 1 minute 26 seconds.


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## LithiumaniacsEVRacing (Oct 9, 2010)

1S test to 150 amps:

http://youtu.be/shVYiU_LNAU


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## LithiumaniacsEVRacing (Oct 9, 2010)

It seems when I test one cell the meter only allows me to draw 150amps from a single cell, but when I test 3S 12V or 4S 16V it allows me to draw 300+amps, can anyone help me with this?


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## LithiumaniacsEVRacing (Oct 9, 2010)

Another test on same 4S pack. Little more amps draw. 

http://youtu.be/cnDFJJjU3A0


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## dougingraham (Jul 26, 2011)

LithiumaniacsEVRacing said:


> It seems when I test one cell the meter only allows me to draw 150amps from a single cell, but when I test 3S 12V or 4S 16V it allows me to draw 300+amps, can anyone help me with this?


Probably the voltage drop across the transistor switches limits the load current when using a single cell. Not much you can do about it if that is the case.


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## PStechPaul (May 1, 2012)

This would be perfect little PIC project. Here is an outline of what I would do:

1. Make or get a load capable of dissipating the power needed. 3V at 600 amps is 1800 watts and 0.005 ohms. You could use a coil of wire in a bucket of water as a poor man's load. Or you can get 6 pieces of 0.03 ohms 220W resistor for $17 each:
http://www.surplussales.com/Resistors/WireWound/WW0-0499.html

2. Get a 500 amp 50 mV shunt, or as low as 250 amp for a 2x overload for a couple minutes. $25:
http://www.surplussales.com/Transformers/CurrentT-2.html

3. Get a Microchip (or other) development board, like this, for $100 or less:
http://www.microchip.com/stellent/idcplg?IdcService=SS_GET_PAGE&nodeId=1406&dDocName=en010072
or this for about $22:
http://www.newark.com/olimex/pic-p40-20mhz/development-board-for-40-pin-pic/dp/25R4927
or this for $17:
http://www.newark.com/olimex/pic-p14-20mhz/development-board-for-14-pin-pic/dp/52R3655
plus a PIC16F684 for under $2:
http://www.newark.com/microchip/pic16f684-e-p/ic-8bit-mcu-pic16f-20mhz-dip-14/dp/29H9638
and the PICkit3 for all PIC projects, $42:
http://www.newark.com/jsp/search/productdetail.jsp?SKU=25R8311

4. Get some high current MOSFETs or IGBTs that can be paralleled for safe handling of 500 amps at 30 volts or more. Like this which is good for 75A continuous and 30V. Use 6 in parallel, $4.65 each:
http://www.mouser.com/ProductDetail/International-Rectifier/IRF2903ZPBF/?qs=2r01AXMCG3MQuqRBwIyfTcHGDHV%252bztH05PX10GXFf2c%3d

5. You will need some other parts like capacitors and resistors and op amps and gate drivers. Maybe $10 worth of parts.

6. Connect the 6 power resistors to the six MOSFET drains, to the positive battery test terminal. Connect the source pins together to one side of the shunt. The other side of the shunt will be the negative battery test terminal and your circuit ground.

7. Set up the PIC to provide a 0-100% duty cycle drive to the MOSFET gates, at something like 1kHz to 10kHz.

8. Make a differential amplifier to read the shunt voltage and multiply by 50 so you get 0-2.5 VDC from 0-50mV for 0-500 amps, and connect to one of the A/D pins.

9. Make another amplifier to read the battery voltage up to 24 volts, divide by 10 for 0-2.4V to another A/D pin.

10. Connect a pot to another A/D pin for current set control.

11. Add START and STOP buttons.

12. Set up the serial port to send the A/D readings to the computer. You can just use HyperTerm or other similar terminal software, and just send all three readings 4 times per second.

13. Power up the board with 5VDC from an adapter or the USB port. It should start with output turned off 0% duty cycle. The pot can be turned to set, say, 400A for 2VDC. The Hyperterm display should read this voltage as the setpoint.

14. Connect your battery. The voltage display should read the voltage, and current should be just about zero. The A/D converter is 10 bit, so you should be able to read four full digits to better than 0.1% accuracy.

15. Press the START button, and the PWM should increase until it supplies the requested 400A. The software can be set up to ramp it up over one or two seconds or as quickly as 100 mSec or faster.

16. The controller should hold that current within a couple amps, and it will be monitoring the voltage and sending readings to the computer. You can have it automatically shut down at 50% of initial battery voltage or whatever you like.

17. The possibilities are endless. You could set up a test sequence at several pre-programmed levels. You could have the current turn off every couple of seconds to get one or two open circuit readings, which can be used to determine internal resistance. You can add a temperature sensor which will track the rise over time and shut down at some point. You could add an LCD display and keypad for display and programming. 

18. For a finished product, you could use a USB PIC and have a Windows GUI which will nicely display the data and show graphs and spreadsheets and save the results to a database. You can even get an Ethernet enabled PIC and set it up as its own mini web server and access it with an HTML web page anywhere in the world, or from an iPad or Android App.

Probably more than you need to know, or are willing to do. But to me this would be a cool weekend project and I already have all the parts I need. If it would be a valuable commercial or hobbyist product, I think it could be built for under $100, especially using surplus parts. Of course the devil is in the details, but if you would like to build something like this, I'll gladly help. If you just want a poor man's version you could do it with a surplus 500A IGBT module and a 555 timer and a few odd parts, and a makeshift load. Let me know...


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## Arlo (Dec 27, 2009)

LithiumaniacsEVRacing said:


> I have tested my Haiyin 400amp cells only to 100amps with my equipment, the factory claims they tested 400+amps per cell.
> 
> I have bought a basic automotive load tester (design for 12v batteries) that will pull 300amps, so I built a 1P 3S pack for testing. Will this work?


I did this to test cheep RC lipo packs I found with 4s 5 ah 20/30C Turnigy RC lipo I could pull 300 amps at 14.3v it was charged to 16.8 The load tester was the cheep hand held type. It got hot in the back fast. It actualy load tested better the the YTX20 and YTX24 that we have in the harleys!

But I do belive you will need 3-4 cells in series to get 300 amps from the load tester. Or you might get 100-200amps from a single cell! Just because the push from the Cell is to low for the load tester resistance.


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## LithiumaniacsEVRacing (Oct 9, 2010)

Thank you all for the info! 

Here is my latest 5S test:

http://youtu.be/6847LBDzySY

400+ amps!!!


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