Suspected Converter Problem

BFL13 wrote:
You have the required 60a fuse/CB on the converter-battery path. But it seems there is no fuse/CB for when you are on shore power with the converter supplying the DC fuse panel. IMO that pos wire should be fused too.

The "return wire" if a second pos for converter- fuse panel needs a fuse too. You could put another fuse /breaker on the pos wire going from the converter to the fuse panel side of the 60a breaker there now. That would take care of both those wires going from the 60a breaker to the fuse panel if the supply were converter instead of battery. Right now, they only get protection if the supply is battery.

You could confirm that mystery "return" wire is doing what you think, by disconnecting the other wire and see if you still get supply to the fuse panel. Disconnect that and unless there is a third path, that should cut off 12v to the fuse panel. Now you know.

Your solar controller is supposed to have a fuse on its pos wire near the battery post. You can have that somewhere close to the pos junction at the inner end of the breaker instead, and let the 60a breaker do the rest of the way to the battery bank.

I agree with what you said. When supplied by the converter, the two wires feeding the DC panel are not protected and should be. However, like I said, it seems they never were (unless there is a hidden fuse/breaker somewhere).

For adding a breaker, what do you think an appropriate interrupt rating would be? I've been told best practice is to fuse for what the wire can handle. In this case, there are (I believe) two #8's feeding the DC panel. However, I don't think it would be wise to fuse them at 80A, since you can't guarantee that both wires would always be intact. If one of the wires worked loose at a connection, for example, you could potentially put 80A through one #8 wire before the breaker kicks.

I believe there are two more prudent ways to do this. One, get a 40A breaker and hook both DC feed wires to that breaker's output. This would guarantee that even if one wire was compromised, you couldn't overload the other. Something tells me 40A would be more than enough supply to the DC panel, considering all the slideouts have there own battery feed via a separate breaker.

The other way I see to handle it would be to use 2x 40A breakers, one for each feed wire. This doubles the available supply to the DC panel and preserves circuit protection in all aspects. I'm just wondering if it is worth the added complexity.

I'm eager to hear your thoughts on that.

As for the solar controller, are you saying it needs its own breaker? I guess I was under the impression that by hooking it up to the "output" side of the battery breaker, it was protected because its current had to pass through said breaker to charge the battery. Maybe this is in error. I guess the question that needs answered is - what exactly am I trying to fuse/protect on the solar controller wiring? This will dictate where I place a breaker (and the rating of said breaker).

My vision now is to purchase a couple breakers as well as two buss bars - one for positive, one for negative.

The negative buss bar would mainly be for convenience to collect all the various ground wires. Through careful planning, I could also make future installation of a shunt very easy.

For the positive buss bar, I envision having the converter feed into the buss bar, and then feed the DC panel breaker(s) and battery breaker off the buss bar. This would provide protection in all directions for all wiring. The only case I can't reconcile is a dead short on the converter output. Would the reverse polarity fuses on the converter open in that instance?

Thanks for sticking with me through this!