How to connect a converter to existing 12V circuit?

[S. Heisley]

I agree that wire nuts are not the best solution and he may have to go bigger. I'd throw some electrical tape around 'em, too, to help hold them in place. I wouldn't want to go bouncing down the road and have one of those nuts work its way off! (It would be better to use terminal and ground busses, if possible.)

Most, if not all, WFCO converters have fuses in them to protect the wire lines.

[Nobody]

The WFCO 9800 series converters have fuses ONLY to protect the converter in event the battery is connected in reverse polarity. They'll 'blow' after one second of reverse connection. Of course then there is no current flowing thru the converter & I'm not sure if there'd be any damage to 12vdc lights from a reverse connection from the battery. Other appliances connected to such might experience damage or perhaps not even work?? I just hate to see any circuit without some kind of fuse/breaker, especially in a mobile environment.

[S. Heisley]

Interesting. I wouldn't have guessed that. Here's the protection listed on the 9800 series:

http://www.wfcoelectronics.com/document ... Series.pdf

I think it must be hard wired in via the breaker. Here is what the manual says:

"Electronic Current Limiting Automatically shuts down power during overload or short-circuit conditions. Automatically returns to normal operation after conditions are corrected."

"There are two signs of an overloaded converter:
Low output voltage, and full converter fold back or shutdown. In both
cases, the converter will automatically turn ON, once the complete load
is removed. For low output condition, removing the extra (over the
current rating) load will be sufficient. If it is impractical to remove all
the load, resetting the main breaker will have the same effect."

I think breakers are better than fuses. You rarely have to replace a breaker.

[dh]

As to the reverse polarity fuses, wouldn't they also protect the battery from recieving a reversed charge current? Self resetting breakers have a place but imho in the event of a short I would rather have a fuse blow and stay dead than have a breaker cool down then give juice back to the circuit. Imagine bouncing down the road and having a wire rub its insulation off. Hit a bump, trip the breaker. Breaker resets untill you hit the next bump and short again.

[digimark]

I'm going to add an inline fuse holder and fuse to the wire -- it's too easy not to. I'm also planning to solder the wires together -- four wires terminating in a wire nut seems like a recipe for disaster down the line.

The WFCO has a single 40A fuse on the front of it. With my modest amp draw (4 lights, 2x 2A fans, iPod and cell phone charging), it shouldn't blow unless there is a REAL problem... so I probably don't need to carry a spare fuse, true? Or is that also a no-brainer, cost vs. misery if it blows in the field?

There's no getting over I'm going to have to run some wire, solder some joints, tote that bale, lift that hay... I'm so lazy.

[S. Heisley]

dh wrote:

As to the reverse polarity fuses, wouldn't they also protect the battery from receiving a reversed charge current? Self resetting breakers have a place but imho in the event of a short I would rather have a fuse blow and stay dead than have a breaker cool down then give juice back to the circuit. Imagine bouncing down the road and having a wire rub its insulation off. Hit a bump, trip the breaker. Breaker resets untill you hit the next bump and short again.

That makes sense. I think I'd install a battery disconnect that would protect you in the above scenario. The battery could be activated once parked at the campground. One should have a battery disconnect anyway as it prevents battery drain.

Digimark:
Although it is always good to be protected, I would call the WFCO service line and ask them if you need that in-line fuse. The write-up on your converter reads as if everything is already protected. Do add and use a battery disconnect, if you don't already have one.

Unless the campground electrical has a problem, if the converter/battery fuse is going to blow, it will probably happen when you first hook up the battery. Still, it doesn't hurt to carry an extra fuse for that campground possibility. They're small and don't take up a lot of room. So far, around here, I've only found 30 Amp ATO/ATC fuses and they only come one to a package (not expensive). I'm still looking for a source for 40 Amp fuses. If you're out camping when it blows, you could have problems finding the fuse you need.

[dh]

I hope I'm reading this wrong and you arn't sugesting he wave fuses on the supply lines and the branch circuits and rely on the overload function of the WFCO.

[S. Heisley]

dh wrote:

I hope I'm reading this wrong and you arn't sugesting he wave fuses on the supply lines and the branch circuits and rely on the overload function of the WFCO.

In adding a battery disconnect, I was referring to your comment about something repeatedly shorting out and then resetting whenever a bump in the road came up. If the battery is not connected, there is no power to short out anything when he’s traveling. (Not that it won't happen when he's camped; but, in your scenario, it is less likely to happen once parked.)

I am suggesting that he ask the experts at WFCO as to whether or not he should add more fuses, rather than solely relying on yours or my opinions. Since they are expected to know their products, they should also know the best way/place to add the fuses, should they decide that they are necessary. It is always best to start with the experts and go from there.

[dh]

dh wrote:

I hope I'm reading this wrong and you arn't sugesting he wave fuses on the supply lines and the branch circuits and rely on the overload function of the WFCO.

In adding a battery disconnect, I was referring to your comment about something repeatedly shorting out and then resetting whenever a bump in the road came up. If the battery is not connected, there is no power to short out anything when he’s traveling. (Not that it won't happen when he's camped; but, in your scenario, it is less likely to happen once parked.)

I am suggesting that he ask the experts at WFCO as to whether or not he should add more fuses, rather than solely relying on yours or my opinions. Since they are expected to know their products, they should also know the best way/place to add the fuses, should they decide that they are necessary. It is always best to start with the experts and go from there.

OK, so what happens if you are running on the battery? The overload won't kick in, nothing is protected. What happens if a led light on a 14g wire malfunctions and draws 25A (not likely, but you get the picture), which will fry the wires but will not overload the WFCO?

I bet I know what the "experts" will say...

[dh]

I'm going to add an inline fuse holder and fuse to the wire -- it's too easy not to. I'm also planning to solder the wires together -- four wires terminating in a wire nut seems like a recipe for disaster down the line.

The WFCO has a single 40A fuse on the front of it. With my modest amp draw (4 lights, 2x 2A fans, iPod and cell phone charging), it shouldn't blow unless there is a REAL problem... so I probably don't need to carry a spare fuse, true? Or is that also a no-brainer, cost vs. misery if it blows in the field?

There's no getting over I'm going to have to run some wire, solder some joints, tote that bale, lift that hay... I'm so lazy.

If only using one fuse for all those wires, make sure your fuse size matches the smallest wire in the group.

[S. Heisley]

Sorry, dh. I misread what digimark wrote to mean that he didn't want to make the updates. Thanks for re-posting what digimark wrote. Hope I didn't get you in too much of a hissy-fit.