Quote:
Originally Posted by Eli81
A screencap of our test program's screen, testing a stock stick...
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Trying to understand that screencap, Eli...
It started with a fully-charged stick, which measured 8.0v with no load. Temperature was 71-72°F.
It charges at about 10A for 5 minutes, bringing the stick voltage up to 9v.
It stops charging, and just sits there for about 40 minutes, during which time the stick voltage hovers at about 8.7v.
It starts discharging at about 20A, and continues to do so for about 14 minutes, except for four short intervals of about 15 seconds each, during which it draws about 100A. Temperatures of the six cells peak at 80-81.5°F.
The test ends when stick voltage under 20A load drops to 5.5v, which occurs after a total of 6457 mH-hr of charge has been discharged from the cell. The stick voltage averaged just under 7v over that 14 minute discharge time, which would mean the stick discharged about 45 W-hr of energy.
After the test ends, the no-load stick voltage rebounds to 7.1v.
Is that about right?
The most impressive thing to me is the IR (internal resistance). It appears to be extremely low! Look at the voltage drop during those 15-second 100-amp loads. In each case, the transition between a 20A load and a 100A load appears to cause about a 0.1V drop in cell voltage, and a 0.6V drop in stick voltage. That's very low: R = V/I = 0.6V/80A = 0.0075 Ω = 7.5 mΩ, so
the stick's total internal resistance is about 7.5 mΩ, and the per-cell internal resistance is about 1.25 mΩ (milliohm).
What software & hardware is this tester? Is it a commercial product?
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BTW, what's the shipping charge to NC for that DIY kit?