Battery Drain

[Christinelf]

Hi,
So glad to find this forum and hope someone may shed some light on our problem. We have a 1998 30' Land Yacht, and the batteries drain after only a few days. Let me clarify, we bought it in Nov. 2010, it sat in our driveway till June 2011 and started right up. We then went cross country with no problem( except our tow dolly, which is another story!) Since then, the batteries drain after a couple of days. Even using the "kill switch" the batteries drain. We have had it in to the Airstream dealer and they said it was the batteries. They replaced them, but the batteries are still draining.
I looked at a few old threads on this topic from 2002, and decided to join and seek some current advice from those "in the know" so to speak.
We would love to be able to decide to take a trip, and be able to just get in and drive away!

[idroba]

It is very hard to diagnose electrical problems from afar. Generally a motorhome (I am not even clear it is a motorhome, but the reference to tow dolly is a clue) has a two battery system, one is for the engine and related parts, the other is for the coach itself, and supplies the power for the lights, pump, fans, furnace etc. Both battery sets are charged by the engine when it is running, and when parked and plugged in the coach battery(s) are charged by the built in converter/charger. So, there are some interactions between the systems, but not total.

So, which batteries are "draining" and how do you know that.

In short, much more information is needed to really help you much, along with your level of tinker skills. Mostly it sounds like you need a good local RV mechanic to diagnose and solve your problems. Unfortunately it is not ever going to be possible to get into your 15 year old motorhome and just drive away. They are very complicated machines with many systems, both engine and drivetrain related and coach related. Usually something is not working properly, which is why I suggest you find a good RV mechanic and have a healthy checkbook.

I hope that does not sound too harsh, it was not intended that way. The problem could be minor or significant, the solution easy or complicated, there is no way of telling at this point from your original post.

[Excella CM]

Here is something you can do to begin to sort it all out.
1) Charge both batteries.
2) Disconnect one wire (ground is best) from each battery.
3) Connect a small 12v bulb (tail light or brake light or amp meter if you have one) between the battery and the disconnected cable. do this for each battery in turn.
4) If there is current flowing, the light bulb will glow. No glow means no drain in the system, hence internal shorts in the batteries. If the bulb lights, then you need to trackk down where the current is going by plullilng fuses one at a time until you isolate the faulty circuit.

[DaveFL]

I had similar problem, if i don't plug it in, in a week house batteries would be down(replaced batteries), put in a quick disconnect at the battery so when it is parked without plugging in I can isolate the house batteries, they will hold charge for more than a month if disconnected. I did put an amp meter between the house batteries and the house and found with all lights off it was discharging at .25 amp not too much for two deep cycle batteries if they are in good condition, but 24/7 comes out to 42 amps and old batteries would be down, new batteries give about 100 amp usable so a couple of weeks would run them down too.

[HowieE]

If you have 2 or more batteries one may be draining the other. Charge the batteries overnight. Disconnect the ground wire on each battery and test the voltage with a Good meter. If there is a seen difference. the lower battery is taking a charge from the higher one and will drain it is short order.

Always replace batteries in sets. Never replace one.

What may have happened during your cross country trip is one of the cells in one battery may have gone bad.

[Wazbro]

As said a motor home has 2 battery banks, 1 for the coach and 1 for starting.

As far as I know they only have a factory "kill switch" for the coach batteries, so the starting battery would still be connected.

From your post it sounds like the starting battery is the problem, can't be sure though.