Thanks, I always pre-charge with a resistor before connecting the inverter to the batteries (otherwise I think the batteries will shut down). Thanks for the pointer on the balancers, makes sense especially as the batteries age.

Thank you for the very quick response. Bypassing the the BMS and charging the cells directly with a 10A current source worked great. After the voltage rose to around 12V or so I switched back to the main terminals. Very nice build quality inside.

No, I don't have this balancer. I used the batteries all summer long and they worked great.

Yes I have an IP65 12v charger I can use. My first charge before installing with the PV system was with that, although I wired them 12V 4p for that first charge, not individually.

Update: Now, 4 hours later at about 6:20pm the batteries are taking a charge. The CC shows 52.83V at 11.4A in the "Bulk" stage. All I did was leave the CC on and wait. Now the battery is behaving as I would expect. An hypothesis is that the batteries were too hot earlier. The ambient temp was about 90F however the batteries were in the sun, so it's very possible the cases got much much warmer. Now it's only 77F and the sun is far less intense. Would we expect a battery to show an "incorrectly" large voltage when being charge when too hot?