Is the internal BMS and circuit breaker enough on EG4 Wallmount batteries?

[DeeK]

I am trying to find out if it's advisable to install a Class-T fuse between the EG4 wallmount 14.3 kWh batteries and the inverter? I believe their internal BMS is supposed to limit current and then there's the breaker/switch as well but is that enough or should I add a T-Class to deal with catastrophic scenarios? I am confused because the T-Class fuses appear to be slow blow which doesn't sound protective for a catastrophic grounding event with LiFePO batteries.

 

[HighTechLab]

If you just have one battery, I wouldn't sweat it. When you start adding more batteries though, that increases the amount of current available for a fault, and additional fusing is a good idea.

Slow blow means that its going to take a bit to (heat up) blow when you are pushing the rated current; when you have a catastrophic failure, the current spikes fast enough to blow it regardless. While it is blowing, you have an arc inside the fuse to deal with, and the class-T fuses are better at handling (extinguishing) that arc.

 

[DeeK]

If you just have one battery, I wouldn't sweat it. When you start adding more batteries though, that increases the amount of current available for a fault, and additional fusing is a good idea.

Slow blow means that its going to take a bit to (heat up) blow when you are pushing the rated current; when you have a catastrophic failure, the current spikes fast enough to blow it regardless. While it is blowing, you have an arc inside the fuse to deal with, and the class-T fuses are better at handling (extinguishing) that arc.

very helpful, thank you!