Coach electrical not running on batteries

[cnijsse]

I'm trying to determine which component of the coach power system is faulty. 

I picked up my 2005 Chinook Concourse (2004 chassis) a couple of years ago. We've put a few thousand miles on it. The coach power worked as it should, giving us lights, fridge, etc. for a reasonable amount of time.

Recently, with new coach batteries and a good charge, my LVD goes into alarm immediately and drops out power within the 1 minute as designed for low batteries.

Coach power works fine with the engine running, on generator or shore power, but as soon as it goes stand alone on battery, it drops out.
The coach batteries are holding 12.2v. My converter puts out 12.8v when on shore power, 13.9 when it's on engine power. As soon as I drop it to battery, the converter shows 9.3 volts until the LVD shuts it down.

Two different shops have told me that the converter is fine, but I'm thinking they tested it with the equivalent of shore power, and that may be misleading.

One shop told me that the overhead coach/store switch was bad, but I've tested it using a different switch and get the same alarm. Sometime after these issues started, I replaced the battery separator as the original caught fire (since then I read the post about them being recalled). I couldn't read the model number due to the char, so I  replaced it with a Sure Power 1315. The relay kept flicking back and forth when on shore power, so I assumed it was the wrong one and replaced it with the 1314. That one seems to work. I can hear the relay click when I use the coach battery boost for engine start.

I'm now back to thinking either the converter is bad, or the connection from the coach batteries to the converter is bad.

I know that was long winded, thanks for your patience. 

I appreciate any thoughts on solving this.

[Manitou]

just guessing here, but sounds like 1 or more batteries have died (internal short maybe?). Seems like a good excuse to upgrade.

[caconcourse]

There are two circuit breakers (a 15Amp and a 50Amp) between the coach batteries and the LVD that may have corroded or stopped working, resulting in a low voltage disconnect. They are mounted under a plastic box-like cover underneath near the driver door step. The 15 amp has a smaller red wire the LVD uses to sense the batteries for low voltage. The 50 amp has bigger wires that carry the full load to/from the batteries/charger. There are posts on this forum addressing the breakers. Do a search on "circuit breakers" and you may find them.

[red_land_baron]

The batteries have a ground connection to the chassis underneath and inboard from the battery compartment. You will have to crawl under the battery compartment to see it. My 2000 Concourse was faulty from the factory. I removed the connector, drilled a new hole in the chassis, scraped the area, and re-mounted the connector with stainless hardware which solved my (your) problem. I then spray painted the connector with black paint. There are 2 or 3 more connections to the chassis on each rear corner of the coach. I did the same for those.

[cnijsse]

just guessing here, but sounds like 1 or more batteries have died (internal short maybe?). Seems like a good excuse to upgrade.

Thanks Manitou. They're less than 3 months old and a load check verified them. But that was my first check.

[cnijsse]

Thanks everyone for your input. Looks like I have some crawling and scraping to look forward to. I've already found the cover for the circuit breakers, so I'll start there. I'll post if cleaning connections was the solution.

[noluck]

have you checked voltage at the LVD

[cnijsse]

I found the 50A and 15A auto-reset circuit breakers under the battery box as suggested. Of course, they were so corroded, that when I tried to remove them and clean them, they disintegrated. I replaced them, as well as the ground connection to the frame...and it works! Thanks everyone for your help! They certainly didn't design it for easy maintenance. I swapped skin for fiberglass slivers in my arms doing the repairs, but after having two "professional" diagnoses point me in wrong directions for a lot of money, I'm happy to have found this resource to help me with my Chinook.

Thanks again!