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-   -   Chassis battery won't stay charged (https://www.thorforums.com/forums/f4/chassis-battery-wont-stay-charged-13251.html)

Troutkiller 07-23-2018 02:38 PM

Chassis battery won't stay charged
 
2017 Challenger


Plugged in to 50A and for the second time in 3 months my engine battery is dead as a doornail. I replaced it a couple months ago because it wouldn't hold a charge. As soon as I put it in the MH started right up.


7 weeks later even the horn won't honk. Nada.


Pretty sure I had switch in "Store" position but can't be positive.


What's goin on here and how do I fix this?


Thx

Beau388 07-23-2018 03:09 PM

If you are plugged into shore power, the engineers that designed your electrical system ASSUMED you are using your coach; therefore, the store/use switch would always be in the USE position. The batteries (house and coach) will not charge if the store/use switch is in the STORE position. The only time you should turn the store /use switch to STORE is when the coach is NOT connected to shore power and you don't plan on using the coach for a couple days or more. Thus, to charge the chassis battery the engine must be running or the store/use switch must be in the USE position.

16ACE27 07-23-2018 03:22 PM

I agree with Beau on putting the USE/STORE switch in USE if the coach is plugged in.

I'm not so sure the chassis battery isn't supposed to charge when plugged in regardless of the position of the USE/STORE switch as that switch (relay) just disconnects the house batteries from the DC buss. If the voltage on the DC buss is high enough above the chassis battery voltage, shouldn't the cross-connect engage and charge the chassis battery?

I'd be looking at that cross-connect relay. Start by engaging the emergency start switch and see if it switches position.

Troutkiller 07-23-2018 03:30 PM

Thanks.


Im a slow learner so be patient.......


I don't savvy how it drained the chassis battery if:


a. It was in "Store" position and should not have had any drain; or,


b. It was in "Use" position and was on 50A shore power


I'm horribly inept when it comes to electrical stuff. Like the worst.

16ACE27 07-23-2018 03:39 PM

Well that's the second part of the mystery.

1. Why wasn't it kept charged regardless of the USE/STORE switch position?
2. What could be draining it?

Your dash radio does have a constant 12 VDC line to maintain memory settings that goes to the chassis battery. I'm not sure what other constant 12 VDC load would come off the chassis battery.

Beau388 07-23-2018 03:54 PM

Quote:

Originally Posted by Tfryman (Post 133440)
Well that's the second part of the mystery.

1. Why wasn't it kept charged regardless of the USE/STORE switch position?
2. What could be draining it?

Your dash radio does have a constant 12 VDC line to maintain memory settings that goes to the chassis battery. I'm not sure what other constant 12 VDC load would come off the chassis battery.


The entire front cap is powered by the chassis battery through the 100 amp circuit breaker under the hood by the chassis battery. The fuse panel down by the drivers left foot distributes that electricity. Things like mirror heat,mirror controls, fans, map lights, windshield wipers power to the jacks controller, ect. all come of the chassis battery. The only exceptions are the Ford supplied items, the chassis A/C, the radio and the 12 volt receptacles which are supplied by the Ford power distribution center..

16ACE27 07-23-2018 03:59 PM

Quote:

Originally Posted by Beau388 (Post 133444)
The entire front cap is powered by the chassis battery through the 100 amp circuit breaker under the hood by the chassis battery. The fuse panel down by the drivers left foot distributes that electricity. Things like mirror heat,mirror controls, fans, map lights, windshield wipers power to the jacks controller, ect. all come of the chassis battery. The only exceptions are the Ford supplied items, the chassis A/C, the radio and the 12 volt receptacles which are supplied by the Ford power distribution center..

But the question isn't what is powered by the chassis battery; the question is: What is continually powered by the chassis battery when the ignition is off that could be draining the chassis battery?

scrubjaysnest 07-23-2018 04:34 PM

Quote:

Originally Posted by Tfryman (Post 133445)
But the question isn't what is powered by the chassis battery; the question is: What is continually powered by the chassis battery when the ignition is off that could be draining the chassis battery?

This is a hard question to answer since it varies from model to model and within a model line.
The computer(s) that Ford install for the engine are powered all the time for sure. on our Axis the camera splitter is powered all the time.

There is also line from the parking break and something that looks at if the coach is in park that feeds the camera system to turn on the radio.


Batteries also self discharge about 1 to 3 percent a month.

Bob Denman 07-23-2018 04:49 PM

1 Attachment(s)
There seem to be lots of parasitic losses; that our batteries need to cope with! :facepalm:
About once a Month: I plug the coach in, and set the Use/Store switch to "Use"..
After it gets about a week's worth of juice: it gets unplugged, the switch gets set to "Store", AND I physically disconnect the batteries with a bayonet switch that I added. :coolsmiley:

No more batteries draining out so quickly! :thumb:

https://www.thorforums.com/forums/att...1&d=1532360920

petefoss 07-25-2018 12:57 PM

Just a FYI but I was told by Thor directly that on my 31W class C the chassis battery is NOT charged by shore power. While it is on most class A coaches they don't set up C coaches that way. As always your situation may be different but I will add a disconnect to the chassis before winter along with one on the coach side too.

SuperD 07-25-2018 01:28 PM

Quote:

Originally Posted by Troutkiller (Post 133438)
Thanks.


Im a slow learner so be patient.......


I don't savvy how it drained the chassis battery if:


a. It was in "Store" position and should not have had any drain; or,


b. It was in "Use" position and was on 50A shore power


I'm horribly inept when it comes to electrical stuff. Like the worst.

In the store position there is still considerable parasitic drain that will drain the batteries in a very short time. (varies from coach to coach and model)

I have never really figured out why the use/store switch even exists because there is still a drain on the batteries!!!

If you were plugged in and switch was in the use position your batteries should be charged, need to check your charger output.

Bob Denman 07-25-2018 02:01 PM

1 Attachment(s)
Here's a picture of the bayonet switch installed.
(Sorry about all of the dirt...)

https://www.thorforums.com/forums/att...1&d=1532523670

The Gritz Carlton 07-25-2018 02:05 PM

Bob...I don't see any "fresh" signs in the dirt where you've checked your battery fluid levels lately. Those flat panels can be gently pried off. Let's get to it!!

Bob Denman 07-25-2018 02:21 PM

:D That was the "Before" picture...
They're clean enough to eat off of now! :thumb:

(By the way: good eyes!!)

The Gritz Carlton 07-25-2018 02:32 PM

Worked as Marketing Manager for an oil company years ago (early retired from them) back when everything was full service and "gas stations" sold TBA...(Tires, Batteries & Accessories). Never have gotten over it. I'm the anal guy that will start critiquing your car when it hits my driveway. My kids make sure their oil is changed, tires rotated, etc., before they will come see me. I wish I could let it go!!

JamieGeek 07-25-2018 02:33 PM

Quote:

Originally Posted by petefoss (Post 133872)
Just a FYI but I was told by Thor directly that on my 31W class C the chassis battery is NOT charged by shore power. While it is on most class A coaches they don't set up C coaches that way. As always your situation may be different but I will add a disconnect to the chassis before winter along with one on the coach side too.

Easy enough to check with a voltmeter if Thor is correct or not.

petefoss 07-25-2018 03:15 PM

True and I plan too.

scrubjaysnest 07-25-2018 05:05 PM

Quote:

Originally Posted by SuperD (Post 133886)
In the store position there is still considerable parasitic drain that will drain the batteries in a very short time. (varies from coach to coach and model)

I have never really figured out why the use/store switch even exists because there is still a drain on the batteries!!!

If you were plugged in and switch was in the use position your batteries should be charged, need to check your charger output.


On our Axis the use/store switch only connects or disconnects the house batteries from the DC distribution panel. While this is typical for RV's it may not always be the case.
With our current set up and the use/store switch in store there is still a 0.1 amp draw on the house batteries 24/7. About half that is our solar system electronics. I also disable the Trombetta isolation between the cranking and house batteries to insure there is no draw that way.

mark4Jesus 07-25-2018 08:08 PM

Quote:

Originally Posted by The Gritz Carlton (Post 133894)
Bob...I don't see any "fresh" signs in the dirt where you've checked your battery fluid levels lately. Those flat panels can be gently pried off. Let's get to it!!

How often should battery fluid levels be checked? I on other vehicles I've had, I check every three months or so.

Bob Denman 07-25-2018 08:12 PM

I'm figuring that a three Month cycle should be plenty safe enough... :thumb:
After a couple of cycles: you can always stretch it out a bit... :coolsmiley:


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