Properly fusing inverter with two feeds?

[belfert]

I have an inverter/charger that is fed by both house batteries and a feed from the alternator.  How do I properly fuse this?

I am redoing my wiring because I had a large DC breaker that somehow physically jammed and quit working.  I bought a single T class fuse as replacement.  If it was just doing battery and inverter it would be easy.

Do I need to separately fuse the feed from the alternator?  If I can use just one fuse for everything do I hook the alternator on the inverter or battery side of the single fuse?

[richard5933]

Wouldn't the feed to the inverter be where the fuse would go? Shouldn't matter how many charging sources you connect to the battery bank. My thought is that you are protecting against the inverter pulling too large of a load should there be a catastrophic failure or overload situation in the inverter.

The alternator would be connected to the battery bank just like a charger would be. I've got a buss bar where my battery bank positive connects with the various charge sources we've got (120v charger, solar charge controller, and 24v-to-12v charger). There is a lead from this buss bar to the inverter with an inline fuse.

All that said, I'd also have a catastrophic fuse in the feed from the battery bank to protect them against a short elsewhere in the system so you don't have a meltdown.  Whether or not you also need a fuse in the feed from the alternator is not something I can say with any degree of certainty.

[belfert]

I am attaching a quick diagram to this post showing what I am thinking.  Is my thinking correct?  Should I move the alternator to the other side of the fuse, or fuse the alternator separately?

[Bill Gerrie]

Yes. Move so it feeds the batteries.

[thomasinnv]

Does the alternator supply the chassis batteries also? Or is it a dedicated house battery charger? In either situation the alternator should connect directly to the batteries, and the inverter fuse needs to be placed between the house bank and the inverter. If the alternator is dual purpose you should have an isolator or relay and a fuse between the alternator and house bank. If single purpose then you don't need a fuse between alternator and house bank.

[belfert]

The alternator charges both house and chassis.  I have a solenoid for the alternator that I didn't show because I didn't think it was relevant to the question.

I am thinking the alternator connection already has a breaker on it.  I don't have OTR A/C so I repurposed the solenoid for the A/C to charge the batteries.  I think the solenoid is fed from a large circuit breaker.

[bevans6]

Just put the fuse as the last thing before the inverter.  You can feed the fuse with any combo of sources you want.  I have a marine type combiner switch that lets me run from the bus alternator, the bus start batteries (plus alternator), the house batteries or all three at once.  All though the fuse.