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Old 11-13-2018, 01:46 AM   #1
Junior Member
Brand: Thor Motor Coach
Model: Axis 25.3
State: Texas
Posts: 5
THOR #13383
Another Dead Chassis Battery

Hi all,

I know there are a few similar threads on chassis battery drains, but I think mine is a bit unique so I appreciate any and all input:

2016 Axis 25.3 purchased in September. Spent most of the month learning/cleaning/prepping so a few weekends in the driveway and storage facility during the week. At this point, my facility was so new it didn't have electricity so I just put the coach in "storage mode" and didn't experience any issues.

We took our shakedown trip the last weekend in September, parked it on Sunday and plugged it in. My particular unit doesn't have 30 amp service so I used a dogbone/surge protector. We also left the refrigerator on since we were going on another trip in 4 days.

We went to the storage facility on Thursday (4 days), and the coach wouldn't turn over, but the dash lights came on and the starter clicked. I used the emergency start and it started (house batteries were fully charged). I left it running while we loaded, turned it off, same result so I figured the battery had just expired. Off to the auto parts store. They thought the battery was junk too, so I bought a new one and off we went. Four day trip with no issues.

Fast forward to last Friday evening, the coach was in storage for about a month and was completely dead--no dash lights, no starter clicking, just dead. I tried the emergency start, and nothing (panel says house batteries fully charged). So I pulled the battery and took it back to the auto parts store. Their analyzer said "charge and retest" but the guy could tell I had two very sad little boys so he just replaced the battery under warranty. I installed it, and of course it started right away. We went ahead and took our two day trip with no issues.

With all of the above said, here is my thinking...er, confusion:
1. Clearly the chassis battery is not charging when the coach is plugged in which I thought it would.
2. If this was purely a parasitic drain, I would think this would have happened when I was just using "storage" mode back in September AND if it is charging, it's gotta be a huge drain.
3. Could be a combination of #1 and #2, but why did it start after I started leaving it plugged in vs. in storage mode?
4. I can't figure out how having the refrigerator on would have any effect on the chassis battery.
5. I'm thinking this must be a BIRD/Thrombetta issue? I haven't gone through the testing procedure in the Felker manual yet, but will.

Anyone else have any idea what could be draining the chassis battery or have this issue in the past?

I'm not opposed to installing a chassis battery disconnect (it's in storage now with the negative cable disconnected and in storage mode), but I'd really like to keep the batteries charged by keeping it plugged in if I can. Plus I really want to understand why this is happening.

On the bright side (I think), I'm really good at changing the chassis battery!


cofred is offline   Reply With Quote
Old 11-13-2018, 11:31 AM   #2
Axis/Vegas Enthusiast
JamieGeek's Avatar
Brand: Thor Motor Coach
Model: Axis 24.1
State: Michigan
Posts: 8,478
THOR #1150
A few thoughts:
  • You may not be as unique as you think: Sounds to me like you have your BIRD/Trombetta miswired so that it isn't closing when the converter is running (Others on the forum have experienced this with Axis/Vegas units)
  • Install two disconnects (one on house, one on chassis batteries) ASAP

2014 Thor Axis 24.1
2018 Chevy Bolt
blog - https://spareelectrons.wordpress.com/
JamieGeek is offline   Reply With Quote
Old 11-13-2018, 12:13 PM   #3
Senior Member
Brand: Thor Motor Coach
State: Illinois
Posts: 212
THOR #5112
i remove red and black battery cable if i leave it sit more than a week. if not it is dead. now i have no problem.2016 thore Axis.
tigwelder is offline   Reply With Quote

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