9 replies to this topic

[johnbruce]

Parked the coach. It set for about three weeks. Went to start it and found the engine batteries completely dead. House batteries fine. Could not find anything left on. Why? Things have been fine up till now. I have 2005 Itasca horizon 400 Cummins. I think batteries were new Jan 2011. Off brand batteries.

[wolfe10]

John,

Welcome to the FMCA Forum.

There are lots of parasitic loads on the chassis batteries (engine computer, transmission computer, usually dash radio, etc). So, with no charging, it is not unusual for the batteries to discharge in three weeks.

Are you storing it where you have access to a 120 VAC outlet?

Brett

[Koliver]

Once you get your batteries back up, you need to put a positive cut off between the ground (black) and the battery post, so as to be absolutely sure there are no parasitic loads draining the batteries while you are away. There are knife switches and fancier things that operate with a remote fob. Just be sure the circuit is demonstrably open while you are away.
My own experience was to find new batteries drained in under 3 weeks, by those loads. I blame principally the ECM on the CAT engine. It is not necessary to keep that energized while not using the coach. The only reason I could find for keeping it on was to keep the ECM warm, so as to avoid condensation. If that is a concern, you will need to be plugged in to shore power.

[dbeatty]

I experience the same problem of dead batteries when the coach is parked for 15 or so days; even when connected to 50 amp service. I thought that when connected both the house and chassis batteries were being charged. On this most recent occasion I was told that only the house batteries are charged, not the chassis batteries. I have a 2008 Monaco Diplomat. Is there any modification/addition that can be made to also charge the chassis batteries when connected to shore power?

[kingfr]

I experience the same problem of dead batteries when the coach is parked for 15 or so days; even when connected to 50 amp service. I thought that when connected both the house and chassis batteries were being charged. On this most recent occasion I was told that only the house batteries are charged, not the chassis batteries. I have a 2008 Monaco Diplomat. Is there any modification/addition that can be made to also charge the chassis batteries when connected to shore power?

Get a battery minder. (Trickle charger plugged into a 115 outlet in your coach.) Mine came equipped with one, never had a problem, even going several months without cranking the engine.

[Peggy]

Just curious...Do diesel engine motorhomes NOT have an aux start switch available to them? Is there something about diesel-engine batteries that forbids an aux start switch in a coach? Am asking because none of your answers mention it. Maybe an aux start is not as common as I thought.

My gas Ford coach has an aux start switch that really saved my situation when I got a bad battery that frequently went dead. Just make sure the house batteries are well-charged by plugging in the coach to shore power (if they are low and you need to), then hit the aux switch and start the engine. You can even leave the shore cord attached when doing this, although it's not necessary. Unplug prior to driving away, of course!

[wolfe10]

Peggy,

Good question. And the answer is YES and NO.

YES, most diesel coaches have a battery boost/battery combine/emergency start switch just like most gas coaches do. They serve to combine the CHASSIS to the HOUSE battery bank. They can be combined to bring the battery with more charge to bear whatever you are trying to start-- main engine or generator. But, view this as an emergency technique ONLY.

NO, that is not a solution to the chassis battery going dead. Repeatedly deeply discharging a battery materially shortens its life. Jumping the coach to start it (which is in essence what you are doing with the boost switch) WILL allow you to start the engine, but should be viewed as an emergency response, not proper long-term solution. The proper answer is to find a means of keeping the chassis as well as house batteries charged.

If 120 VAC available where you store, that may involve a trickle charger or something like the Xantrex Echo charger to maintain the chassis battery. If stored outdoors with no 120 VAC, that may mean a solar panel and controller. If stored indoors and no 120 VAC that may mean totally disconnecting the battery bank during storage to materially reduce the rate of discharge.

[vtbigdog]

For those people whose chassis batteries are not charged automatically, install a Trik-L-Start and then never worry about the chassis battery going dead again.

[Koliver]

Seems to be a frequent problem. In my case, the chassis batteries were supposed to be kept up by a combination of: 1 alternator (when the diesel is running), 2 solar panel (14x14), and 3 echo charger (for when the AC charger has brought the house batteries up and it reaches sufficient voltage to now give a little to the chassis batteries. When parked, there are loads that don't turn off unless you put on a disconnect (see my post earlier in this thread). You need at least one of the charging sources noted to be working at a level that will exceed the draw. In the winter, in northern latitudes, forget the solar panel, as it is not adequate. If plugged in, the echo charger should do it, but, as I discovered, those fail. I now have a dedicated trickle charger plugged into an AC outlet, that gives the chassis batteries all they need, provided there is expernal AC available. For the times there is none, the positive cut-off is a must, or the Chassis batteries will die.

[johnctysonfmca]

Some coaches including mine are equipped with factory disconnect switches. Mine has a disconnect switch, one for the chassis battery and one for the house batteries. When I store the coach I turn switches to off. My coach also has a solar charger which will still maintain batteries, even when disconnect switches are off.

I suspect some of you might have this arrangement and if so you only need to turn off these switches.