Thanks for the considered response! The guys at RPE in Vegas and my dealer (Lennys in Madison) are saying it's proprietary :/ and its a 2015 era display push button on-off. Good cells. I found these online below and pinged RPE and Lennys but no reply
I agree with Thomas. A 4 year old battery is close to it's useful stage. The cells will always show voltage but that doesn't mean there still good. As soon as a load is applied the voltage will drop which is what happens to tired cells.
If you can't get help from the maker, I'd press RPE a little harder. They require the original battery, BMS and battery charger to rebuild a pack. They supposedly test everything, they should be able to give you some help here. These aren't the days of hand written work orders. One would think there are records of the work performed. If not for the customer, for other future rebuilds. Good luck!