I will ask about this 42.5 is that works ok.. is that the charger that cuts out or the circuit board under the seat? As I have just had that altered so that it cuts out at 45v as before ( original ) it cut out at 50v
I got my charger strapped under the aluminium seat-plate. ^.^'
Sadly not much of the original Electronics is left in my EL - so I don't really know what you have there. Maybe a photo will help clear things up as the pros here told me exactly what was original after I posted a snapshot in another thread.
In my case it's the charger itself that stops working at roughly 42,5V(the cells reset to around 41,6V shortly after) and restarts at around 41,3V. (Measurements taken during operation in my EL so those may vary on different batteries.)
In my case the original BMS "only" does the balancing of the cells and the general surveillance (current, voltage, temperature, charging-state or rather used Amp-hours, etc.)
I guess the circuit-board included in your packs might be a balancer (maybe it was able to communicate with the original vehicle somehow, but I guess that doesn't matter as the EL has no means for using this communication).
So if I were in your position, I'd check if the balancer is working properly by measuring (and documenting) the individual voltage of each single cell. Theoretically these numbers should vary only in the 100ths (0,0X V). If it varies more, then you should charge the Pack fully and see if the balancer-board gets warm/hot. That would mean that the resistors are discharging single cells to even out the voltages. This could take several hours. After that the voltages should be almost identical in each cell.
Be careful on the first charge though - if the balancer and/or one or more cells are damaged already there might be risk of fire. I think it would be best to try that outside or in a garage or some other place that can be well ventilated and has nothing in it that might catch fire and is sealed off agains the living-areas so possible smoke can't get there.
Other than that the BMS-board should theoretically provide safety against deep-discharge, overload, over- or undertemperature charging or discharging an overcharging as well as shut off the pack if a single cell is defective to prevent damage to the rest of the pack.
Unfortunately I can't think of a low-tech possibility to check those functionalities without risking severe damage to the pack so I guess we'll have to trust that board if the balancing works properly. (Maybe someone else here has some ideas..?)
Alternatively it's of course possible to switch the old BMS-board for a new one with the specifications of your liking.
You should be able to find BMS-Boards on Aliexpress or the like quite easily.