Brand new batteries, only 37.1 volts

[JohnnieB]

Something is wrong someplace, 37.6V is only 83% SoC and you've got new batteries.

At this point, I'd start eliminating the possibilities.

If possible, use a different DVM for the voltage measurements.
If possible, use a different charger, or try your charger on a different cart.

Remove all wires and cables from the battery pack except the five that connect the six batteries in series and the two connected to the main plus and minus terminal that connect to the cart's charge receptacle.

Verify the On-Charge voltage at the main battery terminals and the voltage on the red and black wires attached to the charger's control board are identical. (By On-Charge voltage, I mean when the charger's ammeter is reading 5A or more.)

Verify the On-Charge voltage of each battery is within 0.1V of the other five.

[yurtle]

I haven't had a hydrometer for decades, but from the chart, it looks like three decimal points is ideal. I'm more asking than suggesting, but I'd assume that at least two decimal points would be necessary?

[theskyiscrying]

I'll try those things and report back my findings. Thanks all

The option of another charger is not an easy option. I've got a pretty decent 12 v charger. Can I connect two batteries in series and charge them that way and see if thy come up?

[JohnnieB]

Originally Posted by theskyiscrying

I'll try those things and report back my findings. Thanks all

The option of another charger is not an easy option. I've got a pretty decent 12 v charger. Can I connect two batteries in series and charge them that way and see if thy come up?

Yes. Take them up to 15.0V for the pair. (7.5V On-Charge for each battery)

[theskyiscrying]

Interesting development.
I unhooked the other wire from pack to controller, plugged charger back in and went to town to do some errands.
While I was out I stopped by HD and picked up a $50 Klein multimeter.
When I got home the charger had turned off. I checked the voltage with old and new meter and guess what???? New meter reads 1.2 volts higher, so a 37.1 now turns into 38.3....
We shall see later this evening, but that's my guess.

I've got a multimeter for sale cheap if anyone needs one

[simple man]

Originally Posted by yurtle

I haven't had a hydrometer for decades, but from the chart, it looks like three decimal points is ideal. I'm more asking than suggesting, but I'd assume that at least two decimal points would be necessary?

Most of the ones you will find have 3 decimal places. They are less than $10 at most any auto parts store.

[yurtle]

Thanks for the info. I had a big one in the 70's, but the bulb dry rotted, and since most car batteries are "maintenance-free", I've never replaced it.

[theskyiscrying]

MYSTERY SOLVED

Yesterday I picked up a $50 Klein multimeter.
This morning I checked the pack voltage, 12 hours after the charger shut off, with old and new meter and there is a 1.2 volt difference between the two.
The new meter reads 38.35 and the old meter reads 37.1



Thanks for the help guys, you're the best

[JohnnieB]

Glad to hear you found the problem.
Thanks for the feedback.