Is it possible to work out the current or power a device is drawing/using, based on the following information:
- Maximum capacity of a battery (48 Ah)
- A table of voltage readings over time (starting at ~13v ending at ~11v over a period of 40 days, sampled every day at 2pm, ignoring the end part of the test where the battery voltage drops off non-linearly)
I am doing this to try and estimate how long the device would work on batteries of different capacities to the one tested, and I have a feeling it's not as simple as just dividing the battery's rated ampre-hours by the number of days it lasted and extrapolating…!
Thanks in advance for your help.
Best Answer
Measure the current directly. Put a low ohms value resistor in series with the load and then measure the voltage drop across this resistor. Trying to do this by the schemes you are trying are at best an experiment.
You are in selection mode not high volume production mode. A few extra components and a little extra circuitry to do it the direct and correct way is the best. The cost is inconsequential.