Connect fuse directly to battery terminal?

Yes, you can and I did that exact thing.



Any time you have wire connected to a power source in a vehicle or trailer, there should be some sort of circuit protection for the wire.

FWIW, I have possibly a similar situation where the converter, inverter, and solar controller have their own circuit protection. I chose to use a 150 Amp mega fuse at the battery's positive (+) post to protect that circuit.

If you are worried about the intrinsic damage from the fuse if it should blow, encase it in some clear shrink wrap or, as Mex advocated once, spray on some urethane crack filler. I don't worry about it since the batteries are in a box and that is a catastrophic fuse.

I must have a terrible way of explaining things as I always seem to send people off on tangents.

I know a switch isn't a fuse, I guess I shouldn't have mentioned the switch. So it's about two feet until it hits the circuit breakers. I use circuit breakers instead of fuses in front of the inverter/charge controller. I am still using the factory circuit breaker for the converter.

I still think I'll try to find a way to make it fused, just rarely see anyone with a fuse at the battery.

30 amp is easy.



http://www.genuinedealz.com/maxi-fuse-inline-fuse-holder-w-6-awg-leads-up-to-60a

I think the switch doesn't count. When it is closed it is just more wire that then goes behind a wall off to the converter etc. So IMO you do need a battery fuse close to the pos battery post. A switch is not a fuse.

AFAIK all RVs have a "battery fuse" up by the pos battery post on the wire going back to the converter way back in the RV. (Fuse amps depends on the amps rating of the converter) Not to mention the fuse on the pos wire for the slide (30a on ours), the fuse for the pos wire for the jacks (30 amp on ours), and even the (15 amp on ours) fuse for the pos wire for the LP alarm and radio memory, that all end up on the battery pos..

You are supposed to also have a big fuse on the inverter's pos input wire from the battery, close to the battery. Size of fuse according to inverter's manual.

If you have a big fuse for the inverter, is it ok to just link all the pos wires to that? NO!!!! The idea is to use "buss" rules.

The various wires to the buss (branch wires) each have various size fuses according to the AWG of those branch wires, and the big fat wire from the buss to the battery that takes the total of all those branch wire amps, then has its own big fuse for its own fat AWG.

The wire goes about two feet to a disconnect switch, then continues from the switch to circuit breakers for the inverter, converter, charge controller.

I may have thought of a way of using the fuse by adding a short cable, like 3" over to an open space between the batteries where I have some vertical room.

I just questioned if it was necessary as the OEM wiring just had one of those 30a auto-resetting circuit breakers and pretty sure it was at least two feet from the battery.

Is the fuse necessary? if the wire being protected goes into wall, yes for sure. When that wire acts as its own fuse you can have a fire in behind the wall. OTOH a short wire out in the open that melts may not be any worse than what the battery itself does when it "melts."

In cars, the rule is your battery fuse on the wire going to your audio amplifier needs a fuse within 18" of the battery. If the car is in a crash, making the wire to the amplifier in the trunk (say) melt from battery shorting or whatever, they don't want that fire making things even worse. But that 18" of wire at the battery will be its own fuse before it gets to the actual fuse.

Not really the best IMO. Need to keep the mechanical stress to a minimum.
How many amps?

I have used ordinary ANL fuses with no "holder" on the positive battery post with the pos wire's lug bolted to the other end of the ANL fuse, no problem. You don't need the "holder" if there is no strain on the fuse.

Actually, with a typical battery fuse, the short length of wire from the battery post to the fuse is unprotected, so having the fuse right at the post is better.