# Battery drain



## mljones (Feb 23, 2005)

We have a 1987 motorhome which is experiencing battery drain problems. There are 2 house batteries and 1 coach (start) battery.  All batteries were new. Nothing shows to be actively on including the electric step. However, the batteries are completely drained within three or four days unless hooked to electricity.  We had to change out the ignition switch. I don't know if this could be part of the problem. How do we find the problem?


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## C Nash (Feb 23, 2005)

Battery drain

Raymond,
Like hunting a needle in a haystack.  Start with a volt meter and pulling each automotive fuse one at a time. If you don't have a meter you can disconnect the neg cable and touch back to battery post while watching for spark  (don't recommend this way as a battery could explode) if there is a spark there is something on somewhere. Are you sure everything is off?  The electric step is a problem area even though it retracts. Ck all lighting. Does the horn work? if it has been disconnected at the horn because the horn blows all the time the relay will still be engaged and will pull down batteries pretty quick.  Let us know what you find


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## TexasClodhopper (Feb 23, 2005)

Battery drain

My MH has an isolator that won't let the coach drain the start battery.  I'm curious that the start battery drains down, too.  My MH also has a switch that disconnects the coach completely.

The secret to successful electrical troubleshooting is to "divide and conquer".  Eliminate as many variables as possible before you go pulling wires.

See if you can isolate the coach battery wiring from the start battery wiring.  If you can do that, then measure the voltage on both sets of batteries.  Let them discharge overnight.  The side with the drain problem will have significantly lower voltage.

Keep using this method until you reduce the number of circuits to check.  For this problem to discharge three batteries in such time, then it isn't going to be a "dead" short to ground. You might look for melted wires, otherwise.

Good luck!  Get back to us with more answers and questions.

quote:_Originally posted by mljones_

We have a 1987 motorhome which is experiencing battery drain problems. There are 2 house batteries and 1 coach (start) battery.  All batteries were new. Nothing shows to be actively on including the electric step. However, the batteries are completely drained within three or four days unless hooked to electricity.  We had to change out the ignition switch. I don't know if this could be part of the problem. How do we find the problem?


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## mljones (Feb 25, 2005)

Battery drain

Thanks for your suggestions.  Tried tracing short by isolating start battery and disconnecting it.  The two house batteries were dead the next evening.  Checked all lighting-no trace of power drainage. Checked step-same result. The two house batteries are connected together as follows: cable runs from neg. post to neg. post and another connector cable runs from pos. post to pos. post. Don't know if this is in series or in parralel. No fuse problem.  The problem must lie somewhere within the wiring of the house batteries.


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## TexasClodhopper (Feb 25, 2005)

Battery drain

Ok. You didn't say if the start battery also died, but I'll assume that you meant that it didn't discharge also.

Your house batteries are wired in parallel (12volts).  This makes more energy available to the MH.  Now, we'll assume that you truly know that there is no other power drain in you MH that is draining your batteries (not a good assumption at this point, but it allows the next check to be made.)

Make sure that you give the house batteries an overnight charge.

You need to disconnect ONE of the house batteries by taking the lug off of the post.  I would take off the NEGATIVE (-) lug on ONE of the batteries only.  Let them sit again overnight to test for discharge.  You'll have two possible things happen:
  1. The battery that is disconnected is discharged.  In this case you will probably notice that the OTHER battery is NOT discharged.  You have found the problem.
  2. The battery that is disconnected has NOT discharged, but the OTHER battery (still connected to the MH) IS discharged.  You still have to test the connected battery.  Charge overnight. Disconnect the NEGATIVE (-) lug of this last connected battery from the MH and check it later to see if it is discharged.  If it is, you have found the problem.
  3. The possibility exists that BOTH batteries have discharged.  You have found your problem.

Of course there are other ways to check the batteries, but this is one way.

You may just proven that BOTH batteries are OK.  Now you know that there IS a drain in the MH.  More on that after the battery check.

Now get back to us after you do your homework!   :laugh:


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## Poppa (Mar 11, 2005)

Battery drain

Here we go again, as to the draining down of all your batteries, you have a heavy user that you have not found yet or a DEAD short. A pain in the behind to find ususally.

As to the connection of your batteries two batteries connected positive to positive and negative to negative will totally kill each other over a period of time. If one of those batteries happens to be lower in potential than the other, the total discharge time will be greatly shortened.

This is from many years of having multipule battery hook ups in equipment


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## TexasClodhopper (Mar 11, 2005)

Battery drain

Not meaning to be argumentative (and bowing slightly to your ages of wisdom and experience) you have been stating the obvious fact that ALL batteries exhibit SELF-DISCHARGE.  A specious argument at best.

The object is to find out WHAT is causing this battery drain problem, and it VERY WELL MAY NOT BE THE BATTERY OR THE WAY IT IS CONNECTED.  We don't know yet.

{Gentleman bows slightly and exits stage left}


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## Poppa (Mar 12, 2005)

Battery drain

Texas Clodhopper,
A battery left alone will adventually die on its on after a very long period of time depending on its age and how much the goodies that make it work have settled out. 
Now if you are lucky enough :laugh:  to afford some of the newer jell batteries the problem of being left alone is greatly diminished.

The fact remains when you have two batteries connected in perrallel (guess its spelt right :clown: ) and the are not EXACTLY the same in potential, over time they will do whats in laymens terms fight each other. The greater the difference in potential when they are connected the sooner they will both be dead.   :dead:  Its a fact of life and if there is any doubt get a couple of batteries and hook them up and watch. 

If you look around in the boating and equipment stores, you will find all kinds of gadgets that are used when several batteries are hooked up in parrellel to keep this from happeniing.

I was not insuating that the problem the gentlemen was having was attributed to the battery hook up alone, as the way its draining down there is a strong user that has not bee isolated or a dead short, I was simply letting him know that there are better ways to skin a cat than connecting batteries in parrallel and what he needs to look out for.

As to being argumentative hell everyone likes a good discussion , we can learn a lot for our fellow man at times.


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## TexasClodhopper (Mar 13, 2005)

Battery drain

Well, you're absolutely right.  A good discussion is really informative.

I'm pretty sure there isn't anything in the battery that is SUPPOSED to settle out.  I guess "stuff" on the plates might fall to the bottom, but nothing in the liquid should separate.

As to two batteries of different potential "fighting" each other, that would tend to defy some very well know facts.  If you hook two batteries of different potential together, the one with the higher potential will "charge" the other one and discharge itself until their potentials are equal.  That make sense?  Once their potentials are equal there is little (if any) current transfered between them.

There isn't any more self-discharge with both batteries hooked together than there would be if they weren't hooked together.  Liquid or gel, they just "leak" internally between plates by design.

Now, having said all that, I defer to the "real world" situations that our batteries get into.  Real world situations are harder to predict, because we don't control all the variables.

I've designed equipment with paralleled battery systems (some had 20 batteries) without problem.  As long as you pump those batteries up every once in a while, all will be well.


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## mljones (Mar 13, 2005)

Battery drain

Thanks for all the suggestions and information.  Unfornately, I still haven't been able to isolate the area causing the problem.  As long as I start the motor and let it run awhile every 3-4 days, the batteries don't seem to drain as bad. If it isn't started during the week, that is when the drain is worse. All wires check out ok. No fuse problem can be detected.  How would the converter affect a power drain problem and how could it be checked.  Thanks for any suggestions.


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## TexasClodhopper (Mar 14, 2005)

Battery drain

Well, until you find out if you have a bad battery, there's not much use in checking further at random.

Think of troubleshooting electrical problems as a flowchart of steps to follow.  You eliminate whole branches of checks one by one until you find something out of the ordinary.  THEN you drill down to the details.

Its all very logical!


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## Poppa (Mar 14, 2005)

Battery drain

Once their potentials are equal there is little (if any) current transfered between them.

The above statement is correct in theory but as you say in the real world :blackeye: .

Any way the get may be rushing the situation to get on the road or he has a Battery the just isn't up to parr :question: .

I have run in to a situationas most have where a battery gets a little age on it, its kind of like us old men :laugh: , it just doesn't crank out the amps like it use to


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## ARCHER (Mar 14, 2005)

Battery drain

OK, after reading all of this, I have a new battery question.  If my house batteries (aux two) are the ones that are "maintenance free", meaning I can't check the fluid levels, how long will they last?  The ones I currently have ... have been in my Class A for at least four years and seem to be operating just fine.  they have served me well for the last three winters while in Florida and seem to still have plenty of juice.  I guess when they go bad, they just go bad, right?   :dead:  :approve:    :laugh:


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## Poppa (Mar 14, 2005)

Battery drain

Hey Archer,

There is a meter that you can check these batteries with and most Auto Zones or O'Rielly Auto parts stores have them. They will be glad to check your batteries for you, at least in Louisiana they will.( They think a sale is close at hand)

The batteries you have are like you said they are either good or bad I have yet to see a weak one.


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