Marathon batteries seem to lose voltage too fast

[baymee]

I was watching the factory charger finish up the charge and didn't want to wait till the end. It was at 45.7V and 2 Amps of charge on the meter. When I unplugged, the VM showed 41.8V.

I drove it a very short distance to the garage and did a hydrometer test on each cell of the 6 pack. Each cell of 5 batteries measured 1.265 and each cell of the 6th battery measured 1.285

The batteries are quality Deka from June 2020, new #4 wire is used throughout the entire system and all copper lugs are heavy copper. I fabricated all the wiring/connectors and crimped them with a professional tool. We have been charging after every use. There is no sulfation seen and the water level has never exposed the plates of these "golf cart" labeled batteries. All connections are corrosion free, clean and tight.

What could be the problem? Sometimes you step on the pedal and it won't move. I hear the relay click under the seat but no movement and the battery voltage isn't too low. It works well after a charge until the next event. I have the service manual and did the tests and they seem to show good.

Is it my speed control? The F/R switch is fairly new. The rest is from 1992.

Thanks for any tips.

[baymee]

Pic