Fusing a battery pack

[jdvmi00]

Is it a good idea to put a glass fuse of some sort in a battery pack? I'm not talking about individual cell fusing but rather a single fuse. For example, if the pack is rated at 30 Amp draw and placing a 40 amp fuse at the terminal.

I just don't see how putting a fuse at the terminal would prevent a short circuit somewhere in the pack. I can see how it would protect the load but wouldn't fusing just the terminal still mean that a cell short in the pack could still take out the other cells and possibly cause thermal runaway?

 

[jdvmi00]

I should also mention the 15s3p pack is connected to a BMS. Isn't a fuse redundant in this scenario? Doesn't the BMS provide the over current protection. A cell shorting somewhere in the pack could still cause the battery pack to go up in smoke regardless of the fuse at the terminal correct?

 

[SanchoSanchez]

Hi,

Placing a fuse between your battery pack and load is your last line of defence. BMS's do a pretty good job of protecting your expensive devices but they aren't failsafe, whereas a fuse generally is. Adding a fuse is not essential but is very good practice and in my view should always be done. For the sake of a few minutes extra work it really is worth the effort.

 

[jdvmi00]

That makes sense, kind of like what does it hurt, but it won't prevent a cell short from getting out of control and causing a fire and instead would just protect the BMS and load from damage correct?