I recently installed a dual battery system in my Suburban, using a Cole Hersee Smart Battery Isolator Battery-Related Products | Battery Isolators48530 | Cole Hersee - Littelfuse . If anyone is familiar with this, I have a question- I wired everything exactly as directed, which included a fuse between each battery and the isolator, BUT it didn't specify what amperage the fuses should be. I used what I had available, 60A AGU (glass) fuses, inside weatherproof plastic fuse holders. These fuse holders with this type of fuse builds up heat at the ends, and since the fuseholders are sealed, the heat cannot dissipate. One fuse blew cleanly at the AUX battery, the other (at the starting battery) blew also, but heated up to the point of melting the threads on the fuseholder before opening the circuit. Before I replace the fuses/ holder with something more robust, I need to know what size fuses to use. My alternator is stamped 124A. Any help is appreciated.

 

You'll definitely need fuses rated higher than your alternator, and higher than your starter draw if you want to use the boost feature.
If the wires are sized correctly, secure and protected I don't see a need for fuses.

 

I hadn't even thought about the starter draw with the boost. I think I'm going to switch to high amp circuit breakers or cut them out altogether like you mentioned- the only thing they really are protecting is if one of the cables gets loose and grounds out, right? If I do go with the breakers, any idea what a typical starter pulls in amps?

 

A max of around 300 amps I think. When the engine is really cold.
A 300Tdi can draw in excess of 600.

As for the fuses, look at it this way. Do you have your battery to starter cable fused?

 

I get your point, but isn't a fusible link a kind of fuse? Because I have one of those on my starter cable. Not being a smart a$$, I promise. I'm about ready to do like you said and disregard the fuses entirely, just make sure all my connections are good and the cables don't rub anywhere.

 

OK, say you go the fuse route, slow-blow high amp fuses be the appropriate type of fuse?
Something like this?

 

IF you go high amp fuse route, be sure a spare stays in the truck.

 

If you go with marine grade terminals with the threaded posts for all your electrical connections to mount to, where can you get the main ground cable and positive cable with the lugs on the end to replace the factory cables?

 

A fusible link serves somewhat the same purpose. My land rovers don't have them on the main starter cables.

Likely not. definitely not for a winch. A starter can even exceed 250a at times.

I make cables (I haven't found DII fuse panel terminals for the bat or alt cable though).