chassis battery goes dead

Split from General / Technical for discussion of anything electrical, electronic... 12v, Inverter, Satellite, Headlights, flashlights etc.
BobW9
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Joined: February 16th, 2018, 4:46 pm
Location: Full-Time on the Road

Re: chassis battery goes dead

Post by BobW9 »

If it was radio cab or coach then the start battery would not stay good when every thing is unplugged and in sleep mode.
Yep, Mike, you're right about my suggestion of the coach radio, as my issue there was that it would drain my starter battery while the coach Store was Red, sleeping.
chin_k wrote: December 14th, 2020, 10:27 am The first thing I will try is to disconnect the chassis battery from the chassis components (radio, starter, etc), but leave the connection to the separator. This way, we can narrow down if the issue is on the coach system, or the chassis system.
I agree with chin_k, might be good to disconnect the wire between the coach and starter batteries, either before or after the separator (or both). Be very careful to wrap the bare red positive cable's lug in tape or something, as that will be something of a hot wire and could ground/short big time if it touches any part of the metal frame of the car/engine.

Or if you have the meter for clamping current around the separator wire, then see if there is any measurable current going through it when the coach is on. I really don't think there should be, and certainly not from the starter to the coach batteries, as I can't imagine how the starter could be at a high enough voltage potential with the engine off.

It seems like either that separator wire is involved in draining current while the coach is not sleeping, or there is a device in the coach that uses power from the starter battery via another wire but is switched on via a connection in the coach circuit (so the device is off when the coach is sleeping).

If the problem doesn't occur when the separator wire isn't connected, then I'd reconnect it and remove fuses from the cab's dash. See if maybe the coach system is in fact just used as the switch on a device and one of those fuses connects the starter battery to the device for power.
2000 Concourse, Ford Triton 6.8 V10
Galaxie 1
Posts: 19
Joined: September 28th, 2020, 9:07 am
Location: Visalia Ca

Re: chassis battery goes dead

Post by Galaxie 1 »

Question. Under dash fuses added by Chinook where does the ignition hot tap go? 7.5 amp bottom left corner.
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SMan
Senior Member
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Joined: February 17th, 2015, 1:57 pm
Location: 7 Lakes, WA

Re: chassis battery goes dead

Post by SMan »

If you have access to a thermal camera I would scan the fusebox under the hood for any fuse or relay that has heat when it should be asleep. Wouldn't hurt to scan the coach panel too. There is also an added fuse block near the e-brake under the dash on my 2004. Also I would check any after market add-on such as rear view cameras first as they are a common source of parasitic draw.

Happy Hunting
Steve aka SMan
2004 Premier V10
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