Proper Engine and Coach Battery Wiring?

[MustangGT221]

Sent: 5/5/2004

I just got a 72 Winnie (brave) with a 318 motor. It's been sitting for about 3 years and I'm trying to get it going again. I have two 12v batteries ready to put in it but I'm a little confused on how to hook it up. There are 4 battery connectors in the compartment (obvious) but two are connected to a ground right next to the compartment. One is red that goes to the engine and the other is black which goes all the way back to the generator. I am totally new to these motorhomes and have no idea how they're connections are made. Any idea how this is suppose to go together?

[denisondc]

Sent: 5/5/2004

The two cables that are connected together to a ground in the compartment go to the negative terminals of each battery. The other two cables each connect to the positive terminal of a battery. With a little luck this will be clear when you do put the connectors on the posts. The positive post is slightly larger diameter than the negative, and the cable ends should match the post size. Not that people cant horse them around. Myself, I like to have the positive cable always be red, but some stores dont carry different colors of cable. That black one going toward the generator is the power for the -coach-. Whether its connected or not will make no difference to starting the motor. 

[MustangGT221]

Sent: 5/5/2004 

OK great, thanks.

I was a little confused because of the wiring that is there. One of the two grounds is actually a red wire, I almost shorted the battery right there because I didn't notice they're both going to the same place right away. You'd think there would be some black tape totally over it. The wire going to the generator is black, so I wasn't sure if that was suppose to be a ground or not. You obviously can't have 3 grounds and 1 positive on 2 batteries, so I wanted to make sure before I hooked anything up. Right now I have 1 battery connected, a positive to the motor and the ground. The other wires I left off the 2nd battery. I have power to the dash when I turn the key to "run", the fuel gauge and alternator gauge move, and I have a light that'll turn on under the passenger seat if I flip the switch. When I turn the key to "Start" nothin happens, so I wonder if that is just because I don't have both batteries in.....I'm gonna play with it some more tomorrow.

[denisondc]

Sent: 5/6/2004 7:08 AM

A red cable connected to ground! Yikes! Cables that have red insulation usually have that larger sized terminal hole for the positive battery post. Im sure it wasnt made that way - somebody did a quick and confusing "fix" perhaps.
Many of our motorhomes have a solenoid-relay-switch right by the battery compartment, that would have both of the positive battery cables connected to it; and from which point one of the cables would run to the engine, and the other would run to the coach 12v supply scheme - usually a small 110v powered 12v converter in the rear somewhere. The purpose of the solenoid was to let you connect the two postive cables together. This way you could charge the coach battery as you drove along. I assume you arent confusing the two cables connected to ground with two cables connected to a relay that looks like a 1950 starter solenoid?
You dont need both batteries connected up for the engine to crank and run. If you have electricity to the gauges then at least your fusible link nearby the starter is okay and part of your ignition switch is okay.
Check whether the horn blows. The same fuse that is for the horn/backup lights has to be okay or you wont have power to the starter relay. The starter relay is mounted on the frame rail near the starter -- as opposed to the starter Solenoid that is a part of the starter itself. The relays job is to provide 12v to the starter solenoid when you turn the ignition key: IF you are in Neutral or Park, and IF the fuse for the horn/backup lights is not blown. If you have a short in the backup light circuit, that fuse will blow when you shift from drive to park with the ignition on.
Check that the tranny is really in neutral or park (an old stiff shifter cable can kink when you push the lever into park, leaving the tranny still in-between gears) or the neutral safety switch on the tranny (rear drivers side) wont tell the starter relay to operate. Its connector may be loose, or the switch sticky from "sitting". If you short the small terminal on the starter to the large terminal on the starter, it will make the starter spin the engine, but: you have bypassed the safety feature of the neutral/backup switch - so make sure it doesnt start up and run over you. Your problem could also be a bad/dirty ignition switch or a partly unplugged steering column harness connector, or a bad starter relay itself, etc. All of this stuff is probably 32 years old.

[MustangGT221]

Sent: 5/6/2004

Yes I do have the two ground wires, and then the two wires going to that solenoid-relay switch in the battery compartment. Then the red goes to the engine and the black goes to the generator. So I will attach those correctly to the batteries and see what I can do. I have done plenty of work on my F-150 but have never touched a motorhome so I don't really know how it's setup. Yesterday was my first day looking at it mechanically. Thanks for your help and I will report back soon.

[MustangGT221]

Sent: 5/6/2004 4:46 PM

OK, I got the batteries in and everything seems ok now..I got the engine running!

[wizardbill]

I only have one battery.

[jnish]

I'd like to bump this thread with a related issue. I have a 72 chieftain that's been sitting dead for about 2 years and upon trickle charging the truck batt and attempting to start the engine, I had no Juice to the starter and the battery was already discharged. I looked first at the isolator/mom solenoid to possibly replace that and I'm looking at testing the alternator for failure since I may have fried it running the engine and genset with the mom switch on dual. Any thoughts on eliminating the coach battery from the rig? It's not really necessary for my purposes since I'll have shore power. How can I bench test the solenoid? I'm pretty much completely ignorant of rv battery setups. Thanks all.

[LJ-TJ]

Does this help at all  Hm?

[DaveVA78Chieftain]

http://i286.photobucket.com/albums/ll120/BaileyDave/Winnebago/StartingCircuit.gif

Note:  The ignition system in this drawing is for a 1973 and later chassis with electronic ignition.  1969-72 had point ignition.  Sorry, but I have never made a drawing like this for a point based system.
 
As shown in this drawing, the MOM switch controls a constant duty relay (the silver can in TJ's picture above).  That relay simply cross-connects/disconnects the house battery and chassis battery.  MOM switch normal position has them disconnected (no voltage to relay).  MOM switch MOM & DUAL position energizes the relay cross-connecting the house & chassis battery.
You need to use a regular battery charger to recharge the battery.  A trickle charger would most likely take at least 30 days to charge a depleted battery if it can at all.  If the battery has been dead a while then it most likely is toast.  They do not react well to being totally discharged.

Dave

[JessEm]

Here's what I see inside... The only loose wires I see are 2 large leads. One is coming off the -Neg from the starter battery, the other goes to a silver "cup" (seen mounted behind battery on upper wall). Is that where my deep cycle goes?

[circleD]

That looks like a spark waiting to happen there. Put some electrical tape on the ends of the wires at least for now or disconnect them. If that silver thing you're talking about in this pic is behind the battery that's a solenoid either for a dual battery set up or AUX start. Either way man, take out the battery and start cleaning the contacts on everything you can and check those wires for wear and track them down. A CLEAN CONNECTION WILL SOLVE MOST OF YOUR ISSUES BUT NOT ALL with these old rigs. It doesn't look bad but while you're there get to cleaning and following wires to see what is what then label them Just in case you want to clean and label. Here's mine. http://www.classicwinnebagos.com/forum/index.php/topic,8756.msg43107.html#msg43107The pics are not great but it's alot cleaner now. NEW looking even.

[JessEm]

Thanks circleD. I'm on the cleaning first thing when we get back. We're taking this rig to a campsite for the weekend tomorrow. Perhaps a little prematurely considering I just bought it, and have barely begun to check through everything. But it's just going to be a glorified tent for this weekend... The campsite is only 30 miles away.Any idea where that big wire coming off the solenoid goes? I'm wondering if it's for my deep cycle battery?I read your thread and I intend to do a thorough job like you did!

[burt6666]

The starting battery and the deep cycle (coach) battery will share a common ground.I would think that the other lead with the red cover on it is the positive for the coach battery.The solenoid is to allow the alternator to charge both batteries while driving.There should be a switch on your dash to operate the solenoid.

[JessEm]

Thanks burt6666. That makes sense. From what I've gathered, that positive lead hanging there IS for the deep cycle (auxiliary/coach) battery