Starting Battery not staying charged when plugged in.

[Bob5147]

I have a 2004 American Tradition. Recently, I have noticed that the starting battery is draining when attached to shore power. I am having to turn off the starting battery disconnect whenever I am gong to be staying at one place for more than a day or two. I have checked the voltages which confirm that the battery is not getting any charging voltage. Is there a "fuse" or other device that I should check to see why the battery "big boy" disconnect isn't closing in to charge both batteries. I can use the switch on the dash to "jump" both batteries together, so I know the "big boy" is working. Thanks for any thoughts.

 

[CorinthWest]

On my coach, I have a IRD, not a BIRD. So the chassis batteries don't charge when plugged in to shore power. 2002 is pretty old, so I'm thinking you don't have a BIRD either, which means your chassis battery won't charge when plugged in under normal circumstances. If the battery doesn't go dead when it is disconnected (bad battery), then I would check for a parasitic drain on the coach battery. This is a fairly common problem, and could be leaking alternator diodes. Just a thought.

 

[bmckerchie22]

On my coach, I have a IRD, not a BIRD. So the chassis batteries don't charge when plugged in to shore power. 2002 is pretty old, so I'm thinking you don't have a BIRD either, which means your chassis battery won't charge when plugged in under normal circumstances. If the battery doesn't go dead when it is disconnected (bad battery), then I would check for a parasitic drain on the coach battery. This is a fairly common problem, and could be leaking alternator diodes. Just a thought.

I have an old bus American Eagle 1995. Where would the alternator diodes be located? Anyone know?

 

[GypsyR]

My even older coach has an IRD and it works that way. Once I figured out it was by design I merely take a jumper wire and connect the positive post of the chassis battery to one of my two hose batteries. Then the converter keeps all three charged instead of just the house batteries when sitting long term. On my to-do list is to do something rather more professional than a jumper wire but I haven't quite figured out how to keep myself from forgetting to switch off/disconnect the added connection in normal use. I've got a red "flag" attached to my jumper wire so when I do my underhood checks before going away it would be very hard to miss.

The alternator diodes are internal to the alternator. They don't fail often but it can and does happen. You can look into how to check them or take it off and have the alternator checked by a shop.

 

[CorinthWest]

General Information: A $4.95 VOLT/AMP meter and a couple of jumper wires from Harbor Freight is all you need to check for parasitic drains. Disconnect the positive battery lead and configure the meter for "AMPS". This includes plugging the red lead into a different hole ("10 Amp"), and setting the meter selector to "AMPS". The meter leads will now measure up to 10 Amps of parasitic drain when connected between the positive post of the battery and the (now disconnected) chassis battery lead. Connect 1 lead from the meter to the positive post on the battery, and connect the other lead to the (now disconnected) positive battery cable. Make sure everything in the coach is off, and read the drain. Anything more than about .035 amps (+/- .005 to .010) is not acceptable. This equates to about a third of an amp. If you see more than this, start pulling fuses until it drops to an acceptable level. If pulling the fuses doesn't work, disconnect the heavy red wire on the back of the alternator. If it drops when you disconnect the alternator, you have at least one bad diode and the diodes need to be replaced. You can check the alternator first if you suspect it, and then check the fuses - either order is fine. Remember, CMOS in the ECM, PCM, TCM, Radio, etc. requires a small amount of electrical current to remember it's "learned" parameters, so a small amount of parasitic drain is to be expected. But nothing more than about a third of an amp. Be careful with the disconnected alternator wire since it will draw the full battery amp load through your meter and jumpers if it touches ground (and make one hell of a spark before burning the meter and wires to a crisp, potentially starting a fire). Just don't let it touch ground under any circumstances.

 

[casper3438]

I have a 2004 American Tradition. Recently, I have noticed that the starting battery is draining when attached to shore power. I am having to turn off the starting battery disconnect whenever I am gong to be staying at one place for more than a day or two. I have checked the voltages which confirm that the battery is not getting any charging voltage. Is there a "fuse" or other device that I should check to see why the battery "big boy" disconnect isn't closing in to charge both batteries. I can use the switch on the dash to "jump" both batteries together, so I know the "big boy" is working. Thanks for any thoughts.

In case no one told you, the chassis batteries (starting batteries) only charge from the alternator, plugging in only chrges the house batteries. there is a power off switch in the motor compartment i shut off when not in use that keeps the batteries in check

 

[Wemustrv]

In case no one told you, the chassis batteries (starting batteries) only charge from the alternator, plugging in only chrges the house batteries. there is a power off switch in the motor compartment i shut off when not in use that keeps the batteries in check

So our 2007 Coachman Encore coach when on shore power both chassis and house batteries charge. The same is true when we are on the road. The chassis system charges both house and chassis. Not all manufacturers do things the same so I can not say yours is the same. Here is what I believe, your chassis battery is either bad or there is short or continuous load present. The battery should not go dead in a day even if it is not being charge bower shore power system. Good Luck finding the issue.