Battery charge/discharg plot

Question

Got a new 16-bit A/D. I connected it to the battery to measure voltage (blue plot) and to the 100A battery shunt to measure battery current (pink plot). Positive current is going to the loads (out of the battery) while negative current is charging the battery from solar. The left y-axis is voltage and the right y-axis is current. X-axis unit time is minutes.

Once the GC2 batteries charge to 13.5V, the voltage slope drastically increases. That's a sign the battery resistance has increased. As battery voltage reaches 14.3V the charge controller starts to decrease current. Excess current (the oscillation shown in the plot) is used to charge the chassis battery.

pianotuna · Answer

Thanks Salvo.

chakara · Answer

Very cool - thanks!

dclark1946 · Answer

Why does the battery voltage start out at 13.4? Just completed charging or are you just showing off your new A-D?Dick

mexicowanderer · Answer

Nice. With an extra laptop this trip I'm going to create a history of the 24 cells. What I should do is examine the feasibility of a 12-channel A to D. using E which is enough information for me.

salvo · Answer

Yeah, both. I think the charge controller dropped down to 13.4V. Hooked up the A/D to a Arduino data logger around noon and turned on about 11A of loads to pull battery down. Once the loads were removed, the solar charged the batteries with 4.2A.

I'm able to measure both charge and discharge current because I'm using the ADS1115 in differential mode.

dclark1946 wrote:
Why does the battery voltage start out at 13.4? Just completed charging or are you just showing off your new A-D?

Dick

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Battery charge/discharg plot

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