Community Forums

jerry davis · 02-11-2007, 02:23 PM

Normally I store my 36'05 in the back yard covered and plugged into 30amp shore power.
This last time I decided to not plug in the coach to check the draw on the batteries. I isolated the house batteries with the isolation switch but I left the chassis batteries hooked up.
Unfortunately being somewhat forgetful I didn't check the coach for about 10 days. The house batteries were fine at almost 12.5v but the chassis batteries were absolutely dead.

I have two questions:
1. Where is all the draw commimg from to draw down the chassis batteries (nothing was on in the coach).
2. After plugging in the coach the xantrex charger would not charge the batteries as the chassis batteries were so drained the on board computers would not turn on. I had to connect a regular battery charger to the chassis batteries to get the xantrex to start charging. How can you do this using the house batteries if you do not have access to a charger?

jerry davis · 02-11-2007, 02:23 PM

Normally I store my 36'05 in the back yard covered and plugged into 30amp shore power.
This last time I decided to not plug in the coach to check the draw on the batteries. I isolated the house batteries with the isolation switch but I left the chassis batteries hooked up.
Unfortunately being somewhat forgetful I didn't check the coach for about 10 days. The house batteries were fine at almost 12.5v but the chassis batteries were absolutely dead.

I have two questions:
1. Where is all the draw commimg from to draw down the chassis batteries (nothing was on in the coach).
2. After plugging in the coach the xantrex charger would not charge the batteries as the chassis batteries were so drained the on board computers would not turn on. I had to connect a regular battery charger to the chassis batteries to get the xantrex to start charging. How can you do this using the house batteries if you do not have access to a charger?

swansnest · 02-11-2007, 03:31 PM

Jerry - The same thing happened to us the first time we stored the Apex (for only 5 days). We used an external battery to jump start it. The problem was that it was backed in against a fence and rigs on either side so we could hardly reach 40' back to it! Thrn we brought it home & added a Jump Start pack - wires that come from the front of the coach down to a 12v plug bolted to the front panel in front of the right front tire - that I can run my jumper cables to from the tow vehicle.

What the draw is I couldn't begin to tell you - but there sure is one and we always turn the switch off in the back at the battery compartment when it is stored for even 2 days!

Ted III · 02-11-2007, 04:32 PM

I understand that the transmission among numerous other little items will draw the chassis batteries down. I was told upfront that if I was to leave it more than two days without the charger on that I should turn both battery sections off.

Bigsky · 02-12-2007, 05:59 PM

We had this happen to us also, ours was because of faulty wiring. However the easiest way to charge the engine start batteries in this situation is to jump the positive terminals of the engine start batteries and the house batteries together. Only one jumper is necessary because the negative side is common to both sets of batteries. Plug in the coach to shore power and the inverter will charge the batteries. Once the batteries come up to charge, remove the jumper and all will return to normal.

Al

OldForester · 02-12-2007, 07:48 PM

I find this thread interesting as I was not told to and thus have never disconnected the house and chassis batteries with the isolation switches, and have never had a weak chassis battery. I have left my coach unhooked from power and not started for more than a month and not had weak starting batteries. Perhaps the separate 10 amp solar panel charging the chassis batteries is enough to keep them charged, even in the cloudy skies of the Seattle-Tacoma area.

So this is a surprise to me. One other approach if you have charge in your house batteries but not in the chassis batteries, might be to use the 30 second battery boost switch from the house batteries to help start the engine, get power to the chassis batteries for a few minutes, shut down the engine and then plug in shore power. I would think once you get a little charge in the chassis batteries from the engine's alternator you could move over to shore power and charge those batteries without a problem

lundy · 02-13-2007, 09:46 AM

OldForester: In my '06, when the chassis was dead, the boost would not work (apparently, it gets it power from the chassis side).

BigSky: I, too, have learned the + to + works well. However, until I purchased a GOOD set of jumpers, it was necessary to use both the + and - on the + positive posts because with the cheap jumpers, too much power is lost.

To WRV: I would like to know what major changes have been made in the chassis electrical to cause this power drain. In '99, I purchased a '00 model that was stored, unplugged, for up to 3 months at a time without using either disconnect. Never found it necessary to jump to start.

To Anyone: Is the power drain on the chassis side common to other diesel pushers?

Gary

gjstacy · 02-13-2007, 11:24 AM

We always turn off our isolation switches when we park our coach, and we have never had any problem starting the coach after it was stored for a month or so. Wouldn't it just be easier to do this? Of course, I know nothing of electrical stuff, so I may be missing something.

But, it would be interesting to hear from WRV on what causes the power drain, as Lundy is asking.

jerry davis · 02-13-2007, 06:57 PM

My point is why should parking a coach be any different that parking a car or a semi-truck when it comes to chassis batteries. You should be able to turn off the key and come back in a week and expect it to start without isolating the chassis batteries.

BIGRED1 · 02-14-2007, 05:53 AM

My understanding on this is that the Allison control module and the Cummins engine control modules on coaches equipped with them both still draw power when the ignition key is turned off. There are some coaches where turning off both of the battery disconnects will not kill all parisitic power use because the power to them is directly connected to the batteries. I can't think of an example at the moment, but that's what I've been told.

Kip Barker · 02-14-2007, 06:50 AM

I am not sure what items are causing the draw, but yes, I have seen other manufacturers of DPs that do use battery disconnect switches.

As far as starting, I have been able to use the 30 battery boost and start the generator, let it run for awhile, then use the battery boost again and start the engine.

htg3 · 02-14-2007, 07:31 AM

I keep my 2005 40FDTS in covered storage which does not have electrical service. At first I would just turn off the chassis and house master switches and the batteries would last up to three weeks before I would have to use an external charger with a small generator or a jumper.
I then started disconnecting the battery ground cable. I can now leave it for over a month before I have to give it CPR.
I noticed that, even with both masters off, when I disconnect the ground, there is a pretty good spark. I think someone once measured the "residual draw" at about 0.5 to 0.75 amp.
I know that the modern electronics never seems to be truly "OFF". They design them to keep the time or memory or something that takes a little juice. I have been told that the Activa instruments are one, the transmission has a memory, probably the engine computer, the radios, the TV, microwave, frig and probably the toaster all draw a few milliamps.
That is my unlearned opinion, perhaps Professor EMike could add a few technical terms.
Keep your electrons happy.

Jim A · 02-14-2007, 08:08 AM

I turn off the chassis and house disconnects when I store my coach, and I have left it stored as long as two months and still had both chassis and house batteries that were still charged. But I have the 10 watt solar panel, which obviously wouldn't work in covered storage.

The 120v appliances like the TV and microwave should not draw any current from the batteries even if the disconnect is not turned off. They would draw some residual 120v current if you are connected to shore power, but not 12v. For example, the plasma tv has a red LED power light that stays on even when the TV is off. This light goes out when the inverter is turned off or you disconnect from shore power. Should not be any draw at that point. Same with the microwave. Its the 12v items, like the engine and tranny, you need to be concerned with. The dash radio for example.