Fuse converter, or not?

Snowman9000 wrote:
Been reading archives, but not clear whether a converter's output should be fused. (This is not about the reverse polarity fuses found on all converters.)

Converter output **IS** Fused, by those very fuses you say this question is not about.. So, there is your answer. (not needed)

However you should have a "main" fuse for the battery (or circuit breaker) roughly the size of your converter unless the generator draws more (Assuming you have one) when starting, mine is 80 amps. Same as the converter.

I do not believe the reverse polarity fuses would blow on a dead short at the output. Most that I have worked with are fused far above their capacity- a 45 amp converter will simply not put out the 60 amps needed to blow the reverse polarity fuses.

As long as the wire will easily handle the full converter rating I would not fuse the main connection. Actually if the main wire is safe, short and in plain sight I would also skip the battery side fuse.

ScottG wrote:
The reverse polarity fuses are the fuse for the converters output.
Adding another would be redundant.

Good to know.

As Roy wrote, it needs a fuse or breaker close to the battery for protection for the wires and battery.

OK, as I mentioned, I have that.

The reverse polarity fuses are the fuse for the converters output.
Adding another would be redundant.
As Roy wrote, it needs a fuse or breaker close to the battery for protection for the wires and battery.

The external fuses installed in-line of the main battery cable installation is not there to protect the Converter/Charger unit but to protect the battery cables wiring in case of short circuit at the converter/charger end of the battery cable. Without the in-line fuse close to the battery source could burn down your trailer. Your battery bank will produce a whole bunch of DC CURRENT until the batteries either run down or explode.

I follow these installation techniques around any high current battery cables in both the trailer and truck start battery high current cables distributions.

I have learned along time ago the follow basic installation procedures when working around high current DC cables. It falls under the concept to learn not to burn for me over the years...

Roy Ken

The switchmode converters are inherently output limited, so they do not need output fuses. Theoretically, you can short the output with no harm- the converter just shuts off...... of course, I wouldn't really try it.

First of all, you never NEED a fuse, unless of course you have a short. Are you going to have a short ? That would depend on a lot of things, mostly the quality of installation. If you feel even the slightest possibility of a short circuit happening, fuse it. I myself don't have a fuse inline my stand alone converter. The 0riginal 7345 was not fused either. None of my OEM battery cables are fused either, even the one going all the way to the generator. Many....if not most main battery cables are not fused from the factory,.....maybe because they figure the only way they can short, is in a catastrophic wreck ?? And that's good enuff for me.

KD4UPL wrote:
Anything hooked to the battery will need a fuse. The battery is capable of delivering hundreds of amps during a short circuit. What if your converter shorts internally? How will it do with 100, 200, or more amps flowing thru the short before your main battery fuse blows?

That's why I'm asking. In my case, the main fuse is 100A, though.

newman fulltimer wrote:
the converter wires directly into the fuse panel

I should have mentioned, I'm asking about a separate deck mount converter. It's nearer the battery than the panel, by quite a bit.