Big fuse on battery?

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Last seen: 3 years 3 days ago
Joined: 02/15/2015 - 21:35
Big fuse on battery?

Hi all,

In material that I've read about installing a solar system, it's recommended to put a 100-250A bolt-on fuse on the battery, then bring the charge controller and other lines into that fuse, with additional fusing.  My question is, what purpose does the big fuse serve, if every other draw from the battery is fused at lower amperage than that?

Thanks for the insights.


ac0gv's picture
Last seen: 8 hours 12 min ago
Joined: 09/22/2016 - 13:57
Big fuse

How big is your solar system? The fuse must be sized to the system, 250 amps times 14 volts would be 3500 watts. The largest current flow will be the loads in the RV, not much unless you add a large inverter. Scamps would never have a system this large.I would not spend the money.

ManWithaVan's picture
Last seen: 2 years 2 months ago
Lifetime Member
Joined: 11/07/2013 - 21:56
Why use a Big Fuse

The reasoning behind using a "Big Fuse" at the battery terminal is to act as a "Catastrophic" Fuse and/or a "Fail Safe". This is usually needed on systems with multiple batteries that potentially have a lot of stored energy and could cause serious damage or injury if all that energy is unleashed all at once, i.e.: a bare (positive) cable end gets dropped and hits the frame, without the fuse the cable would just weld itself to your frame. The same is true if a cable wears through and grounds itself, you want the fuse to blow before too much damage can occur.

As Always,

Happy Scamping !!!

Last seen: 5 years 4 months ago
Joined: 01/27/2019 - 12:13
I know this thread is old,

I know this thread is old, but for future reference: You are fusing the wire, not the equipment. If you encounter a short in your system, you want the fuse to heat up and burn out. You definitely don't want the wire to heat up and burn. And you are sizing your wire based on the load you are carrying and how long the wire run is. There are charts for both on google.