38.9v on First Charge w/ New Batteries

cooose

Today after work, I picked up my brand new batteries/cables...got them installed and hooked to the charger just before dinner. I just let the dog out and noticed the powerwise was off. It seemed odd since they were only charging for ~4.5 hours or so. I checked the voltage across the pack and got 38.9. From what I've read on here, this seems low. I've also read a few threads on issues with the powerwise, and most seem to point to issues where the charger doesn't cut off, not where it's undercharging.

My question is, does this seem normal on a new set of batteries? The batteries I got were interstate gc2-rd-utl, which I know are ~ 7% lower than standard AH's

2003 TXT PDS 36v

BGW

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yurtle

Wait 12 hours after charger cut off and measure again. I never watched how fast the surface charge dissipates, but you're above what your pack will settle to.

yurtle

I couldn't tell how soon after charging completed you took your reading but it should have been around 44 - 46 volts when the charger cut-off. It may drop pretty fast at first, or may be completely linearly. I just don't know.

polocheck

I'm rather new but a 36v battery pack fully charged sould read right around 38.2v fully charged. Measurements should be ideally measured 24 hours after the charger stops. You should be fully charged. Anyone else agree?

Knothead

Yurtle is (as usual) correct. 12 hours (of sitting unused) after charging is when you want to check voltage.

Voltage after 24 hours will be slightly lower, but not much.....

polocheck

The main point I was making it that I thought he was fully charged at 38.9 volts.

yurtle

Not sure. Charger turns off when the pack reaches 44 - 46 volts. After a 12 hour rest, it should settle down to 38.2. any measurements before 12 hours are not useful. As I said, I don't know if the surface charge dissipates in a linear manner, but he was above where he should end up, which is 38.2.

Knothead

Agreed......IF it had been a few hours (at least) after charging when he checked the voltage. If the charger had just cut off a few minutes before he checked the voltage, it could be a little low. That's what Yurtle was eluding to. 12 hours is the normal amount of time for the surface charge to disappear & voltage to level off. Since he's got brand new batteries, the voltage & runtime will probably be off a little, until batteries have been cycled a few times.

OP....in case you're not aware, new batteries need to be "broken in" by not going below 75% SOC for the first 20 charge cycles. Read everything related to "batteries' on ScottyB's website: www.cartsunlimited.net

JohnnieB

As mentioned, the 38.9V most likely contains some surface charge, so let them set for about 12 hours after the charger shuts off to get an accurate reading.

After the surface charge dissipates, cart batteries self-discharge at about 1% SoC (State of Charge) per day, which is only about 40 millivolts (0.040V), so the difference between letting the batteries rest 12 hours and 24 hours isn't much.

Also, new batteries tend to read a bit on the high side, so you might see 38.3V or 38.4V instead of 38.2V

Knothead

^^^ The MAN has spoken!