Battery Box switches

cotswoldphoto

New Member
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

Watts are Watts!
Staff member
Moderator
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

New Member
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?
 
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