Brand new batteries charge question

[JohnnieB]

Originally Posted by TexasLongball

Thanks for all the previous help. I figured I'd ask another couple of questions here instead of starting a new thread.

When I was breaking in my batteries, I ran them down to a resting voltage of 37.3. What is the acceptable voltage to keep ABOVE while driving. There have been times when the reading was a lot lower (35ish) while driving and then it would gradually increase again at rest. I want to ensure that I'm not wearing them down too far.

Also, I took my cart to the beach this weekend and when I rinsed off my cart, I hopped in to move it and the cart went about 20' and stopped. The solenoid clicked and voltage showed good but no movement. I got busy doing something else and went back about 30 minutes later and tried it with success. Does water getting on/near the connections cause issues?

The nominal voltage drop for a 36V battery pack is about 1.0V per 100A of current draw and when you include the high current cables, connections and contacts it can be around twice that unless they are in pristine condition.

When battery manufacturers do non-destructive testing, they usually don't drop them lower than 1.75 VPC (Volts per Cell) and there are eighteen 2V cells in a 36V pack, so that is 31.5V.

Irreversible plate damage starts at about 1.5 VPC, so you absolutely want to stay above 27.0V, except in dire emergencies like getting off the tracks while a freight train is heading towards you.

The 35ish volts you saw is normal and fairly typical.

The pack voltage drops fast under load, but recovers slowly. Full recovery takes over an hour, but most occurs in the first few minutes, so for serious battery testing I let the pack rest about half an hour and just a quick check to see when it is time to head for home, I seldom wait more the 5 minutes or so. The SoC estimate I get is low, but that is on the safe side.

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The pedal box and the in-line connector between the cable connecting the cable from the pedal box to the cart's wiring harness are very susceptible to moisture and will cause the symptoms you describe.

You should also avoid getting the controller wet.

[TexasLongball]

Thanks Johnnie.