# Main 12 Volt Battery Died



## ARCHER (Mar 10, 2005)

Got a Class A.  Has engine battery and two aux batteries.  All was good a month ago (started the engine with main battery).  Tried to start it yesterday and main battery was dead.  Nothing runs off main battery while I am at site and all set up.  Plugged into shore power so aux batteries are charging as needed.  The only thing that could of caused this is the radio was turned on and switch was set to main (in lieu of aux) for running radio.  What I don't understand is that the radio was not lit up or actually had sound, etc., until I used the aux batteries to start the engine.  I put charger on main battery yesterday and did an 8 hour charge, so will check to see if it held the charge.  Might be dead.....fried or no fluid (no, I did not check it yet, it was pouring so thought I'd wait until today and then check fluid level)  Shame on me.
Any ideas as to what could have drained the main battery power??? All swithces were in the off mode (except the radio).  Hope I was clear on the radio...knob turned on, but no light in window and no sound, until I started the engine and then it was lit up, etc. :dead:  :blackeye:


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## Shadow (Mar 10, 2005)

Main 12 Volt Battery Died

Archer, how old is the battery? Thats happen to me a couple of times. Truck will start right up,go to the store and truck won't start. Both times the battery was about three years old. Just a thought.


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## Krazeehorse (Mar 10, 2005)

Main 12 Volt Battery Died

That's the way they go a lot of times....in their sleep.  Shadow's right.  If the battery has any age on it it probably is just wore out.  An internal connection is probably bad, not completely open so that you have 0 volts, just poor so it won't carry the amperage and therefore doesn't really charge or discharge the voltage you need under load.  BTW, I would NOT go to wally world or any cheap parts house for this battery.  Stick with a major brand, you definitely get what you pay for in batteries (I happen to be an Interstate fan).  When comparing cold cranking amps between batteries make sure they are using the same test.  Standard BCI tests are conducted at 0 degrees F.  The cheapies test at 32F and therefore have higher (and somewhat bogus) numbers.


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## ARCHER (Mar 10, 2005)

Main 12 Volt Battery Died

the darn thing is less than a year old.  Must of been just something I had on that drained it down to low.....just checked it by turning on the dash lights and they came on so maybe the charge worked and kept it after turning off the radio (even though I don't think that was it), but will let it sit for a couple days and see what happens.  If dead again, will probably replace it.  tks all.....


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## zigzagrv (Mar 10, 2005)

Main 12 Volt Battery Died

Archer, if the ignition was off, the dash radio should also be off. Don't think that was the problem. The only other thing that comes to mind is a poor/corroded battery cable connection. They do seem to corrode quicker during the winter, or at least winter shows up that type of problem due to the excessive load of cooooold engine. Also, if the switch was in the AUX position, I believe the main battery is also connected to the house battery. Since the main battery is smaller than the aux, it could drain down first. :question:


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## C Nash (Mar 10, 2005)

Main 12 Volt Battery Died

Archer, most of the MH steps work off the main battery and that will pull a battery down pretty quick. just another thought


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## ARCHER (Mar 10, 2005)

Main 12 Volt Battery Died

Well, I pulled the battery out today and checked the fluid levels in the cells.  4 of the 6 were way low.  I put distilled water in the proper level and put it on the charger (I carry one with me).  Let it charge for about 6 hours.  Put it back in and so far it has held a charge.  I'll leave it for a couple days and then see what happens.  Hopefully, I got fluid into it in time for a good charge and not cooked.  Question I have is that the Aux batteries are on the entire time that I am parked here for the winter and the converter also charges them as they are used for the 12 volts stuff in the motorhome.  Is it possible that the main battery got cooked by the charger that was charging the aux batteries?  I thought that the main battery was off when the engine was turned off and key in the off position.  It was parked/not used for 3 months and started the engine just fine in early Feb, but when I tried it yesterday it was dead.  Did not make sense to me????
tks for the ideas and help...   :laugh:


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## Krazeehorse (Mar 10, 2005)

Main 12 Volt Battery Died

Put a voltmeter on your main battery with and without your coach charger plugged in and see if voltages are different.  This will tell you if the main is being charged along with the coach batteries.


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## Poppa (Mar 11, 2005)

Main 12 Volt Battery Died

Hey Guys. The ole man is back in town for a while, this stuff called work is killing me  

I had a similar problem with my main battery draining down. Seems like when you shut everything down on these newer 1985 plus vehicles everything is not down. There is the clock, the newer radios have a small amount of juice going to them all the time plus some other things.

Since it first happened to me I have made a couple changes i what I do. One is I kick Nellie Belle off every other day or so cause she's kind of like me, lays around too long and she gets stoved up.  

It keeps her fluids circulated, the engine oiled and electrical system dry besides it tunes up the battery also. Let run long enough to open the thermostat then go about another 5 minutes.

If you don't want to do this, you can install ajumper wire and a swithch from your coach batteries to your engine battery and when ever you park simply flip the switch and you engine battery will trickle charge right along with your coach batteries. BUT ALWAYS REMEMBER TO FLIP THE SWITCH BEFORE YOU START THE ENGINE because you may smoke the jumper wire.


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