Battery Box switches

[cotswoldphoto]

I see that on the Simpliphi their batteries have an over current breaker (that can be used manually as an ON/OFF switch) AND an internal BMS. On their 48V 60A battery I think it is an 80A breaker. I am making my own 48V 70A batteries with BMS (the 48V 70A from here: https://www.aliexpress.com/item/4000136472702.html for $70). Do you think I should add a 100A 48V breaker switch to it?

 

[Craig]

I think it is always good to have a breaker between battery and anything else. Always nice to be able to disconnect things in a hurry if need be or have protection from any sort of mishap.

 

[cotswoldphoto]

Thanks. I will order one today.

 

[April]

PPut one on the PV line too . It stops you being lazy and leaving it connected

 

[cotswoldphoto]

 

[cotswoldphoto]

So. The battery has xxx LiitoKala 32700 3.2V 7000 mAh cells configured as 48v 91Ah (13x7), but I do not intend to fully charge them. I was going to aim for just over 75% charge as maximum using the BMS, so the battery would be nominally 70Ah. So, what switch/breaker do I put on that? In theory, the cells can discharge at up to 6C, but I would not wish to do that. The simpliphi batteries are overspecced in a similar way so that they last a long time (as mine should) and their breaker is 33% higher rated than the battery. Based on that, would a 100A be suitable, too big, or too small?