Thank you very much for this. Invaluable.@BigDean, the 200A model use a relay to switch the battery on/off while the 100A model use a bank of FETs. Both work fine, but I don't think it is economical to add enough FET chips to handle 200A, while the relay (this one with a precharger which is good) has some other drawbacks like being slower to switch.
If the 100A will be enough for your system, then I would suggest that model rather than the relay.
How do you know it will be enough for your needs? That depends on the power you need and intend to draw. 100A x 51V = 5100Watts so if you have a 5kW inverter 100A is your limit in any case.
You need the RS485 or UART interface. The driver don't use CAN. If you can make sure it has an extra interface. On the JBD the bluetooth normally is installed on the UART, so if you get the RS485 port extra then that mean you have the bluetooth and connection to the driver at the same time which is nice.
This will top balance your battery, but you will have to give it time to do that. So build your cells and install the BMS and charge it to around 80-90%. Then disconnect the charging and set the BMS to balance always (and not just on charging) and leave it for about a week. Check daily if the cells have settled and if it is still balancing and you can also top up the charge a bit if you want. You can extend this to two weeks if your battery needs more time. Then switch the balancing back to only on charge and you can begin using it in your system. The BMS should then keep your cells balanced from there on.
It is a 5kw inverter, so the 100A will be the best.
As always with Aliexpress, the advert is not 100% clear, but I think this includes the bluetooth and UART/RS485 connections....: https://www.aliexpress.com/item/100...o.store_pc_groupList.8148356.1.16387277X9TlrE
So hopefully I wont need any additional cables/interfaces!
Thanks again for your help.