Pics of fuse boxes/wiring...please post

[mikeschn]

Hey Steve,

What kind of wiring could cause a problem like this?



Mike...

[Scooter]

I can scan it and post a PDF if anyone is interested.
Bruce

That would be very helpful. Please post when you get a chance. Thanks!

[Steve Frederick]

Hey Steve,

What kind of wiring could cause a problem like this?



Mike...

Hopefully, no one here would do that kind of wiring!!! If any one has doubts as to their electrical understanding,,,, get some help!!
To answer, how about overloaded/undersized wires...Heating up and POOF!!

[norm perkiss]

Scooter,
I found a web page with lots of RV electrical info. It's 2 pages. Lots of good info. From "what is a battery" to "hooking up inverters". I'm no expert, but the info validates all the great advice already posted.
http://bart.ccis.com/home/mnemeth/12volt/12volt.htm
Hope it helps.
Norm

[BoilermakerFan]

Hey Steve,

What kind of wiring could cause a problem like this?



Mike...

Wiring probably didn't cause that fire...

But, an oversized fuse with an undersized wire could overheat enough to catch on fire. That's what the fuses or circuit breakers are for. They are there to protect the wiring from overheating, not to protect the equipment.

Also, a dead short with a high capacity battery would generate a very large spark. If the spark occured near the battery and it had vented hydrogen gas, then you could also have an explosion with the fire.

[bdosborn]

Oh good... I'm glad we are on the right track...

Now let me throw these two questions out...

Should the battery be grounded to the frame?

and

Can you use a battery charger on the battery while running all the lights, etc at the campground?

Mike...

P.S. It's amazing.. no one has picked on Michelle yet for running an obviously "too thin wire" from the battery...

and no one has picked on me for not talking about grounding the frame...

and furthermore, no one has picked on me for the wire sizes, which are close, but not right... i.e. is 8 gauge too thick from the battery, and is 16 too thin from the lights...???

1. Yes, the battery should be grounded to the frame. Its an NEC requirement so there must be a pretty good reason for it. Most of the codes that are adopted are in response to injury or damage to equipment. I'll be darned if I can give you the technical reason. I'll have to look into it.
I'll check the NEC handbook, which usually explains why a code has been adopted. My guess is you ground to the chasis so you don't let the smoke out.

2. It depends on the charger. If the charger is big enough it will power the lights as well as charging the battery. Battery chargers are typically protected on the output so that if you try and pull too many amps out of them they shut down. If the charger doesn't shut down when you're running everything then you're probablly fine.

I'll post my one-line tomorrow. Been way to busy at work. Its a bad thing when work cuts into my Teardrop and beer drinking time.
Bruce

[bdosborn]

Here's a link to a PDF of the wiring diagram sketch I drew out. Let me know if there are any blatant errors on it. The PDF is about 600 KB.
http://home.comcast.net/~bdosborn/tear/ ... iagram.pdf

[mikeschn]

I'm pretty clear on everything except that shunt resistor. What's that for?

Your schematic is wonderful... can you do wiring diagrams also? You know, with a black and red magic marker, and a sketch of the teardrop, etc...

Mike...

[asianflava]

I'm pretty clear on everything except that shunt resistor. What's that for?
Mike...

I don't know excatly what's for but I've seen them on other schematics where you hook up an ammeter.

[bdosborn]

I'm pretty clear on everything except that shunt resistor. What's that for?

Your schematic is wonderful... can you do wiring diagrams also? You know, with a black and red magic marker, and a sketch of the teardrop, etc...

Mike...

The shunt resistor is to read current using the voltmeter. 50mv=50A shunt means that 1mV reading on the 200mV voltmeter indicates 1 amp of current flow. Its a cheap way to have a high current ampmeter without having to rate everything for the full current. The drawback is that the meter isn't nearly as accurate at low current levels as it is at high current levels.

As I get farther along with my Teardrop construction I'll put together a power and lighting plan with circuit connections shown. I haven't decided where everything goes yet. Heck, I might even send it through CAD to get a nice clean copy. That will probablly cost me lunch though...
Bruce

[mikeschn]

I can mail you a couple magic markers... a red one and a black one. That won't even cost you lunch!!!

Mike...

[shil]

Here's what I've done:



The big fat cable from the positive terminal runs to a great big marine switch, just out of frame to the lower right. The return from the switch runs back to a 60A automotive fuse, the little yellow thing mounted on plywood to the right of the battery. From there, a wire leads to a distribution panel mounted inside the teardrop.


The three wire return from the panel runs to the terminal strip just behind the battery. From there, wires run off to the reading lights, the cabin light, and to the 12 volt outlet in the galley, just visible at the right of the picture. All returns meet at a common ground, to the left behind the battery, where another big fat cable connects to the negative terminal.

This picture was taken just before installing the galley countertop. A plywood panel keeps the flying frypans away from things that they could hurt.

I haven't grounded this mess to the frame: that's where I've grounded the running lights. Should I?

[bdosborn]

Here's what I've done:


I haven't grounded this mess to the frame: that's where I've grounded the running lights. Should I?

According to what I've read in the NEC, yes. Everything else looks good from what I saw. I wonder if anyone has had a problem with corrosion on wiring mounted in the battery compartment. Even a sealed battery off gases and the gas is pretty corrosive. I plan to mount my batteries on the tongue in their own box that is well ventilated. I've seen some UPS and generator start battery cabinets that were rusted out from battery gas.
I like that West Marine panel but I plan to make my own distribution box, a lot like the one in the picture that Steve posted.
Bruce

[asianflava]

It may be a good idea to put covers on the positive terminals. Since the entire enclosure isn't grounded it's not essential. There is a possiblity that a wrench or screwdriver could fall across the terminals though.

[Dee Bee]

OK I thought I understood, but maybe I didn;t get it. So help me out....

1) Am I correct that in USA, typically the tow vehicle 12 system uses a negative ground to the vehicle frame? This allows all vehilce 12v light etc to ground to the frame for the return path to the battery.

2) Then when you hook up a trailer with brake lights and running lights, these use the tow vehilce system. The same set up with the return of current from the brake lights turn signal lights and running lights being "grounded" to the frame. Then some where near the trailer hitch, the frame "ground" is picked up by a wire (ususally white) and the return ground is transfered back to the vehicle battery through the wire harness.
Is this how it usually work?

3) If my assumptions are correct the the trailer frame is "grounded" to the vehilce battery.

4) Are you saying that you also connect the battery used only for trailer 12v supply, to the trailer frame ? Where do you make this ground

5) Doesn't this mean that both batteries are sharing the frame as a return path for current to the respective batteries?


6) I was not planning on "grounding" any cabin or galley lights to the frame. Each cuircuit would be hard wired to and from the fuse box, with the fuse box receiving power from the batter and delivering the return back to the battery via wires with correct rating.

7) So help me out. What am I missing?

DEE