Engine battery keeps draining

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6x16inside

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Mar 9, 2017
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I had a brand new battery put in my 91 HR 37ft motorhome in March.  She has been plugged in to my home, no generator and to my knowledge, the two "skanky" batteries next to the bay the would be generator will go are not powering anything.
I just attempted to start the engine just to let it run a bit, first time in approx. a month maybe a smidge less and nope, not happening.  This will be the third time I have encountered this and I don't know why.
Is it being drained by something that isn't powered by it being plugged in to the house or is there a problem with the battery itself despite being brand new or ???  There is nothing up front like cams or radio or lighting that could be draining it and I have the door fully shut now which seemed to be the reason behind the last two times it drained in less than a week and a half apart.
Thanks!
 
A 12 volt lead/acid battery will self-discharge at a rate of about 5% per month - and that's with no phantom loads on it. Many RV converters don't recharge the chassis battery when the RV is plugged into shore-power. Some do, some don't. If yours doesn't, and there are small phantom loads on the battery (which is likely) that could explain why it's dead. Additionally, if you're starting the engine every month or so, just to run everything for a few minutes, the chassis battery probably isn't being charged long enough by the alternator to do it any good. It's dying a long, slow death.

Gary Brinck wrote a good article about RV batteries that you might find informative. You can find it by clicking on the Library link above.

Kev
 
This the cure for your problem. It uses your coach battery to charge the chassis battery. Love mine.  http://lslproducts.net
 
I had this same problem.  It turned out that the CB radio (in the cigarette lighter) was the culprit
 
Kevin Means said:
A 12 volt lead/acid battery will self-discharge at a rate of about 5% per month - and that's with no phantom loads on it. Many RV converters don't recharge the chassis battery when the RV is plugged into shore-power. Some do, some don't. If yours doesn't, and there are small phantom loads on the battery (which is likely) that could explain why it's dead. Additionally, if you're starting the engine every month or so, just to run everything for a few minutes, the chassis battery probably isn't being charged long enough by the alternator to do it any good. It's dying a long, slow death.

Gary Brinck wrote a good article about RV batteries that you might find informative. You can find it by clicking on the Library link above.

I'm sorry?  The library link?  Thanks!
To the others, the mechanic who put the brand new battery in says I simply need to be starting the coach more often whether there is anything running off of it or not.
I will look into the other resources offered here as well.
Thanks all!


Kev
Click to expand...
 
I'm new to the RV world but I was under the impression that the engine electrical was separate from the camper electrical. If this is true, you have something in the cab or under the hood that is draining the battery (eg, CB radio as per Natetheskate above). Until you can get the problem fixed, just start the engine every week or two and let run at high idle until battery is charged.

You can usually track down a parasitic load by putting an ammeter at the battery and pulling fuses until the current drops to zero.
 
My RV Battery article is about RV battery types and choosing among them. See http://www.rvforum.net/miscfiles/Choosing_right_battery.pdf

As others have suggested, the problem is a combination of self-discharge and tiny loads that slowly deplete the charge.  The dashboard items and 12v outlets are usually powered from the chassis (engine) battery, and so is the LP gas detector and the powered entry step.  It is also fairly likley that the house charging system does not charge the chassis battery, so adding the LSL Amp-L-Start or Trik-L-Start device would do that and compensate for losses.  http://lslproducts.net/
 
Just because it is an RV does not keep it from having normal automotive problems. That being said I have seen the alternator cause the problem you have described. A diode can go bad allowing a path to ground which causes the battery to drain. Easy cheep troubleshooting disconnect the electrical connection from alternator and see if the battery still goes dead.
 
sc4668 said:
Just because it is an RV does not keep it from having normal automotive problems. That being said I have seen the alternator cause the problem you have described. A diode can go bad allowing a path to ground which causes the battery to drain. Easy cheep troubleshooting disconnect the electrical connection from alternator and see if the battery still goes dead.
Click to expand...
Concur. Well stated.
 
sc4668 said:
Just because it is an RV does not keep it from having normal automotive problems. That being said I have seen the alternator cause the problem you have described. A diode can go bad allowing a path to ground which causes the battery to drain. Easy cheep troubleshooting disconnect the electrical connection from alternator and see if the battery still goes dead.
Click to expand...

I can BARELY even get to the battery to hook up the cables much less have any clue where the alt is on this thing.
I know like the 3 conversion vans I have owned, it is not IN/under the doghouse so I guess I will be crawling underneath if Oklahoma gets blessed with another few days of the incredible weather we have been having.
Sad to say, something like that is more likely to be the reason than small things stealing the juice as this rig literally does not have ANY cutesy little convenience features.
 
The alternator is located on the front of the engine. You will probably have to get to it from under the RV. Remember to disconnect the battery before you try to remove the wire from the alternator so there are no sparks . Once the wire is removed from the alternator make sure it is not touching anything then reconnect the battery and do your test.
 
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