You build this battery yourself, meaning you have control over the whole process. The BMS is JK with a 2A active balancer. The 4 cells are 628Ah each for a total of 8kWh of energy. This would be my go-to battery if I needed a high capacity 12V battery. The price is cheaper than ready-built batteries, which have worse design and software.
The build quality of this battery is great, and only the software lets it down. There are three issues. First, a safety flaw in the app lets anyone turn off the BMS remotely. Second, the low temperature cutoff is set to -7°C or 19.4°F, which is too low to protect the cells. And third, the battery only balances while it’s charging. There is also a security flaw. Anyone who connects to the battery can shut it down remotely into storage mode. All of this could be fixed with a software update, but I’m not confident the company will do it, so I’ve placed this battery in the caution category.
Battery only balances while being charged, 46mA of balancing current is low, and BMS high temp disconnect is 120°C/248°F which is too high.
Very low balancing current of 35mA. Battery could not charge to 14.2V after 3 days in absorption. Cells are 340Ah but are only pulling 343Ah when I tested them individually which is weird and I haven’t found an explanation.
Balancing current of 35mA is too low and that explains why people mention it doesn’t hold a charge after a while. It becomes impossible to balance, especially when balance start voltage is set to 3.525V. The BMS lets the cell discharge to 2.3V (should be 2.5V minimum). The mosfet high temperature is set to 105°C (221°F)! The build quality was okay, but there were no spring washers and the glue was not correctly applied to the main battery terminals.
Rated 300Ah but only tested 287Ah. The manufacturer told me it were 302Ah CATL cells, but the cells are EVE MB30, They said A-grade cells but these are B-grade. The JBD BMS itself is good and the 200mA balancing is great, but the build quality is poor and out of the box the app settings were wrong, including a low temp charge cutoff set too low at -10°C or 14°F which does not protect the cells if it’s freezing.