Faulty Batteries?

[tsrice]

First off, I am new to the 715 world but I grew up with an M38A1 and M37. Anyway, when I turn on the switch, there is no power. This just happened one day. I checked the voltage off both batteries by themselves and together. One reads 12v the other is at 9ish v. Combined they are just under ten. What is the problem? Is there a short in one of the batteries? Thanks in advance.

Tom

[k8icu]

Sounds like you have to do some trouble shooting. The first place I would start is take both batteries out and charge them up to full charge and then have them load tested. If you have a tester great if not you can go to may autoparts places and they will test it for you.

I know you stated that your know your way around a 24v system but when you rehook the batteries up make sure you have chassy ground to negitive on the first battery, positive on the first battery to negitive on the second battery and the positive on the second battery to the system. I'm not trying to make is sound like your stupid or anything, but sometimes we all make mistakes. I've been playing with MVs for 20 years and once in a while I'll get something backwards.

Then if the batteries check out and everything is hooked up then you need to check for a short of some type. I've seen coils go bad in the distributor do that. One MV I had had a bad light switch and a small amount of voltage was getting to the head light and drawing the battery down. The only way I discovered it was one night when I pulled into the garage and shut the vehicle off and noticed a dim glow thought the black out lights were on...

Good luck, but start with the batteries and make sure they are up to snuff first.

[brute4c]

If the batteres are fully charged and one reads 9 volts, sounds like a bad battery to me...broken plates, dead cell...have them load tested for sure.


One question to add....do you have any 12 volt accessories on this truck that are drawing off one battery and not the other that would drop one lower than the other? If you do, that could very well be why there is a difference AND it could also lead to a bad battery...I have fried 2 that way...
If you dont, then I would bet on the one being bad.

[Binford]

Do as suggested (charge them both up and have them load tested).

Funny, but I had this exact problem this weekend! I charged both batteries and cleaned all the terminals to like new. Still nothing. It just so happened Al (Kaiserjeeps) was stopping by for a visit. When he got here, he suggested we remove the foot starter switch (after disconnecting the batteries first, of course!) and cleaned those terminals off as well. Al wasn't happy with one of the nasty battery cables so he replaced it with a new one I hadn't gotten around to installing yet.

Once all the terminals on the battery and foot starter switch were all nice and clean and reassembled, it started and ran like a champ.

Also, I know that if you have two batteries wired in parallel and one of them is weak, it will draw the other down and essentially ruin it. At least given enough time. But is the same true with batteries wired in series, such as in our M715s? Might be something to watch if one battery does prove weak.

Thanks for the help, Al!

[tsrice]

Thanks to all. Turns out it was a short in one of the batteries. Now its time to get her on the road!