Battery hook up

This is one of the big problems with used MHs. Well meaning people buy RVs and then with minimal knowledge start making changes. By the time you get the end product it is very difficult to sift through the make shift modifications and haphazard repairs that were made along the line of ownererships. Sometimes it is easier to rip it all out and start over. This is one of the big reasons I tend to avoid used RVs. There are some good ones out there but it is also difficult to really see all the repairs until you buy it and start having problems or restoring it. It is bad enough sifting through manufacturing problems when they are new.

First question I would have is the two deep cycle batteries, are they 6V? Or two 12V? If 6V then the negative on one should go to chassis ground, it's positive should go to the negative of the 2nd 6V, and it's positive should go to the booster solenoid on the wall. There should be another heavy cable going to the genset from either the positive on the solenoid or from the positive of that battery set.

If they are 12V batteries, the wiring would be the same, only they would be wired positive to positive and negative to negative as well as having the chassis ground and solenoid cables.

Sometimes, the RV will have the starting cable from the genset connected to the starting (chassis) battery instead of the house batteries.

The negative going to that solenoid must be wrong. There should be positive 12V there.

What yr/model Mallard to do you have? I have a 91 Mallard Sprinter and might have the diagram you need in my tech manual. If not, maybe I can take a couple of pics. As I recall, that white wire comes from your battery charger/power converter and is connected to the battery neg on the house battery.

My configuration was 1 house bat and one start bat. I recently upgraded to 4 6volts so my config might look a little different.

majmikie wrote:
Hi. I have a old Mallard motorhome and starting to retore it. There is one house battery and two deep cycle batteries. Diagrahm is lost of the proper placement of wiring. Help! House battery has pos wire to starter solenoid. Neg wire to ground. Deep cycle #1 has neg to ground and pos to generator. Deep cycle #2 has neg to (booster?) solenoid on fire wall. Nothing on pos side. I have three wires I don't know about. One is a white wire which comes in through the firewall with the large generator wire. The other two are connected. One is red and the other is black. My thoughts are that the red connects to the other side of the booster solenoid down to the pos side of deep cycle battery #2 and then the black (again which is connected to the red) onto a ground. Thanks for any help.

Wow, fast replies. I can tell it has been a while since I worked on this MH. I guess House batteries are the deep cycle ones. I have two of these and they are 12 volt. I love working on this but I failed electric shop (40 years ago) but aced the mechanical part. Thanks Jim.

Tsweez, thanks also. I have left my warehouse but I thought it was an 88. Never saw a model like "sprinter" but I will look again tomorrow. Thanks.

Don't forget one of those positive cables probably goes to a cutoff switch and/or booster switch....Dennis

Thanks Dennis. There is no cutoff switch. I agree probably to the solenoid.

Even if you failed electric shop, best take a volt meter with you and measure those batteries. I think they'll be 6V. They're probably in pretty bad shape so just in case take a gallon of distilled water and a battery filler. Plus you'll probably need to measure voltages on loose cables occasionally.

And of course you could just count the cells. 6 cells is 12V and 3 cells is a 6V.

Maybe take your camera and take some pictures and post them here?

BTW, house batteries should not be connected to the starter...that's the chassis battery's job.

The original owner may have wired it up that way because in most older RVs the converter only charged the house batteries and the chassis battery would usually die if you were parked on shore power for several days. Which is why most of us install a float charger plugged into 120V and connected to the chassis battery. Or some install a Trik-L-Start.