I am finally getting around to connecting up my new replacement convertor/charger. I took the old one out a month or so ago and I'm not 100% sure of the hookup. The red lead is not the issue - but I believe the negative was connected directly to chassis gound. Is his correct? Or should their be a wire to directly to the coach batteries ? I'm sure there was a 12" wire that went from the negative connection to the unit attactment bolt. I should have taken a photo or made better notes...

On my 1973 with the factory installed converter charger the chassis is used as the ground path.

On my coach as it has seen salt I have taken the grinder/sander out and while replacing the engine to chassis ground straps polished things up and then painted over the connection to seal things up. The point being the ground path on my older coach did not offer a resistance free nor a consistent path.

Chioce 1: Pull a ground wire. Good path, known resistance. This is what I suggest, it gives a known result.

If you are going to charge both batteries I suggest a nice big marine grade battery switch. Make sure it is a make contact before breaking contact model. If you take this approach both batteries house and starting will require known grounds.



Choice 2:

Measure resistance from unit to battery. However this approach assumes that there are no components in the chassis ground path that will move as you drive introducing "interesting" variations in the resistance of the ground path.

Choice 2a:

Pull a ground wire to the same frame rail for the batteries and the converter/ charger, this will save some wire. If the frame breaks a soild gound path for the converter will no longer be your primary concern.

For what it is worth.

Timothy

This may not even apply, but just as a reminder.......Unlike a house:



"The neutral and ground in an RV electrical loadcenter are NOT to be bonded together.

The RV chassis is isolated from ground by definition. Metal leveling jacks and such, mounted on the vehicle frame do not make an adequate ground contact. Therefore, in an RV, you always want to have a "floating" neutral, where the neutral and vehicle ground NEVER come together. When you bond the neutral and ground together in an RV, you have a "floating" ground (rather than neutral) and this will result in nutty things happening."

From: http://www.phrannie.org/battery.html

Lee:

This is interesting but I don't quite understand.

Please know that I have not looked at my 110 so I have no idea how things are connected.

It is of great interest that Bill H. make a point to check if hot and neutral are reversed at the RV plug before he hooks up. Yea I understand this problem.

Having said this if I were installing 110 I would connect the green wire, ground or earth if you prefer, to the chassis this way I think I would be protected if I touched the chassis while grounded.

Is my guess correct? Am I missing something?

Thank you:

Timothy

Timothy,

I posted that only as general info...not to advise anyone that their work was in error....

Actually, I posted it as bait, to get billh, Bill NY & Rusty to teach us all something about this....I'm currently in a converter swap-out project myself and need to know this stuff......

thanks for the info - you confirmed what I thought was the way it should be... thanks for the quick response

quote:

Originally posted by Lee:
This may not even apply, but just as a reminder.......Unlike a house:



"The neutral and ground in an RV electrical loadcenter are NOT to be bonded together.

The RV chassis is isolated from ground by definition. Metal leveling jacks and such, mounted on the vehicle frame do not make an adequate ground contact. Therefore, in an RV, you always want to have a "floating" neutral, where the neutral and vehicle ground NEVER come together. When you bond the neutral and ground together in an RV, you have a "floating" ground (rather than neutral) and this will result in nutty things happening."

From: http://www.phrannie.org/battery.html

Asolutely correct.

However, the source is referencing 115 volt AC connections.

Wit 12 volt DC, the chassis and coach frame should always be negative.

BTW, good site, Lee. Everything Phred writes is Golden.

quote:

Originally posted by timnlana:
If the frame breaks a soild gound path for the converter will no longer be your primary concern.


Timothy

DING DING

We have a winner for today's ringing statement of the obvious.

But seriously, everything Tim says about a good clean ground is VERY VERY important. I can't tell you how many trailer and RV electrical problems are caused by a poor ground. Particularly boat trailers. One of my camping friends had a big estimate for complete light rewiring. I showed him how to clean grounds and he solved his problems with no money spent except for a Dremel. I'm sure Bill NY's truck road service sees it a lot, too.

When I did boat electrical work for my airplane customers, I ran a solid bare bus wire around the perimeter of the boat and soldered all negative connections to it and everybody thought I was a genius. Just a simple thing like a good ground can clear up so many different things. I saw so many botched installations just because a good ground was not assured.

Also see Lee's thread especially the descriptions of single output converters (which you most likely have new) and dual-output converters, which is likely what you had.

The only thing that's almost a certainty is that you will have to run a large gauge jumper somewhere if your old converter was a dual-output.

this, and to some extent, this may help.

Actually, neither helped me, but it was easy to track down where the jumper needed to go, as I diassembled the old converter to track down its output wiring.

quote:

Originally posted by Lee:
Actually, I posted it as bait, to get billh, Bill NY & Rusty to teach us all something about this.....

Yer fish'n wit gr8 bate!

I really can't add much to this. About 75% of all road calls are electrical in nature for us.

I would only add that a 12 volt battery is actually 6 battery cells at about 2.2 volts hooked together in series to form what we would call a 12 volt battery. Other then that I have nothing Earth shattering to add. It is otherwise a good great fantastic article.

Unless something is lost in the translation of the article I really don't have much more to add. But, if it's Greek then speak! I'm sure we can explain a specific question better.

Bill N.Y.