Author Topic: Battery capacity tester adc resolution question  (Read 481 times)

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Offline kjr18Topic starter

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Battery capacity tester adc resolution question
« on: March 07, 2019, 09:38:22 am »
Hi, I want to make a battery capacity tester, mainly as a training exercise, as well to use it. It will be only used for AA, AAA and maybe some small li-ion or li-poly cells. I plan to use for this purpose a simple constant current circuit consisting of two opamps, you could say: textbook example. Arduino will be responsible for counting capacity etc.

My question concerns ADC resolution: I know that typical arduino's adc resolution is about 5mV (from 0 to 5V), and if I were to, let's say, connect analog input straight across a load resistor, I would have some error in measurement. It's not much, but what if I wanted to use that measurement to calculate total mAh of the cell? Won't that error accumulate over time? I thought about some other possibilities, like using external higer resolution adc, or using something like INA219 to take care of both battery voltage and current measurement (connect it to load resistor or add small 100mR in series with load resistor). What solution would be the best, also price wise, I don't want to go broke because of this ;D
 


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