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Old 12-12-2015, 09:58 PM   #1
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Brand: Thor Motor Coach
Model: Vegas 24.1
State: California
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Vegas Chassis Battery Issue

We've had our 2015 Vegas 24.1 for 10 months now and, within the last couple of months, the chassis battery has started discharging for some unknown reason. I suppose it's possible that the battery has gone bad, but my guess is a phantom load that I can't track down is draining the thing. We keep the coach plugged into shore power when not in use.

At the moment, it's more of a nuisance than anything else as 20 minutes on a charger will get the engine started. That leads to another question. What's with the emergency start switch?? It doesn't work and seems to have been mounted on the dash solely for decorative purposes.

MikeAndMad
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Old 12-12-2015, 11:41 PM   #2
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Emergency start switch shorts the chassis and the coach battery; or is supposed to. It works great on ours--you do have to hold it in.

Instead of spending countless hours trying to trace down a phantom load on the chassis battery I just installed a knife disconnect switch. When I park it for storage I open up the switch. Haven't had an issue with the chassis battery since.

I now also have a disconnect on the coach battery and leave both disconnected when in storage. So far both batteries have fared well with the disconnect; even with the coach battery being a crappy Harris one.
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Old 12-13-2015, 02:40 AM   #3
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Originally Posted by JamieGeek View Post
Emergency start switch shorts the chassis and the coach battery; or is supposed to. It works great on ours--you do have to hold it in.

Instead of spending countless hours trying to trace down a phantom load on the chassis battery I just installed a knife disconnect switch. When I park it for storage I open up the switch. Haven't had an issue with the chassis battery since.

I now also have a disconnect on the coach battery and leave both disconnected when in storage. So far both batteries have fared well with the disconnect; even with the coach battery being a crappy Harris one.
I've tried holding it in, but it doesn't seem work. Of course, I may be doing something else wrong. Haven't really tried to figure it out as the coach batteries are fine and I can run the generator to power battery charger for chassis battery even if shore power not available.

I've seen a write up on the knife switch. It's an option. What bothers me is that everything worked fine for the first few months and then the battery started going dead after a few days. It's not like this has been a problem from day 1. I'd rather not go that far unless forced to by circumstances (i.e. nothing else that's reasonably easy works).

Our particular unit has a pair of coach batteries and I do have the coach connected to shore power, so I don't really worry about the coach batteries.

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Old 12-13-2015, 03:37 AM   #4
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Originally Posted by MikeAndMad
I've seen a write up on the knife switch. It's an option. What bothers me is that everything worked fine for the first few months and then the battery started going dead after a few days. It's not like this has been a problem from day 1. I'd rather not go that far unless forced to by circumstances (i.e. nothing else that's reasonably easy works).
Ours was like that: Worked fine over the first winter. Left it in storage for several months in the cold without a battery issue. At the beginning of the second winter, though, the batteries wouldn't hold.
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Old 12-13-2015, 04:06 AM   #5
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Ours was like that: Worked fine over the first winter. Left it in storage for several months in the cold without a battery issue. At the beginning of the second winter, though, the batteries wouldn't hold.
Went out in the dark and started the engine after charging the battery earlier today. Noticed that the light to the right of the radio had two small glowing dots, although they were dim. This is the light that goes on when the engine is shut down, is lit for a while and then supposedly goes out. After shutting down tonight, I noticed that the two little pinpricks of light were still there, which indicates there's current flowing. However, when setting the coach batteries to "store", the lights go completely out, indicating they're powered by the coach batteries and aren't related to chassis battery issue.

That knife switch idea is looking better and better.

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Old 12-14-2015, 03:40 PM   #6
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A lot more info is really needed. How long does your coach sit between uses. Yes, You said the house batteries are plugged in all the time, that's good but that won't charge your chassis battery. There is also a parasitic drain on your chassis battery. A knife switch is a perfect answer, but will not tell you why it is draining. so back to the question, how long does it sit between uses. And yes, your dash radio is hooked up to your house batteries.
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Old 12-15-2015, 07:08 PM   #7
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A lot more info is really needed. How long does your coach sit between uses. Yes, You said the house batteries are plugged in all the time, that's good but that won't charge your chassis battery. There is also a parasitic drain on your chassis battery. A knife switch is a perfect answer, but will not tell you why it is draining. so back to the question, how long does it sit between uses. And yes, your dash radio is hooked up to your house batteries.
It can sit for weeks between uses. The first eight months or so we owned the unit, there was no problem. I ran the engine for 30 minutes about 4 days ago after using a battery charger. Started it up a few minutes ago with no problems. I'm thinking about increasing the time between engine starts by 24 hours at a time to determine how long the chassis battery can go before discharging sufficiently to prevent a start.

The first time the problem occurred, the unit had been sitting for 3 or 4 weeks without shore power connection and with house batteries disconnected. Started the generator off the house batteries and used a battery charger to charge chassis battery.

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Old 12-15-2015, 08:36 PM   #8
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Weeks between uses without a charge, your battery is being drained. A new battery of course has a better chance of holding a charge, but the more you let the battery go down the harder it is to charge it up full. A 30 minute charge from your engine is barely enough to charge what it took to start your engine. With the converter running if your battery is 50% down will take 24 hours to charge back up to full. Put a meter on the batter to see how many volts it has. You can get cheap meters at auto parts stores, Walmart, etc. I really think your battery is being pushed to the point of failure. Is it a maintenance free battery or a wet battery, if the latter, you need to keep the water up to level with distilled water.

Even with all the switches in their off position for both coach and chassis there is still a drain on the battery. Leaving it weeks at a time without a charge you are probably reducing the voltage in the battery by a considerable amount. A chassis battery can only handle that so many times before it will not take a full charge again. While your coach batteries are made to handle that load better, they too will be reduced it just takes more time for them.

Also, please note that your keeping the coach plugged in all the time is great for the house batteries, it does nothing for the chassis battery. Perhaps getting a charge on that battery will help.
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Old 12-15-2015, 10:22 PM   #9
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Weeks between uses without a charge, your battery is being drained. A new battery of course has a better chance of holding a charge, but the more you let the battery go down the harder it is to charge it up full. A 30 minute charge from your engine is barely enough to charge what it took to start your engine. With the converter running if your battery is 50% down will take 24 hours to charge back up to full. Put a meter on the batter to see how many volts it has. You can get cheap meters at auto parts stores, Walmart, etc. I really think your battery is being pushed to the point of failure. Is it a maintenance free battery or a wet battery, if the latter, you need to keep the water up to level with distilled water.

Even with all the switches in their off position for both coach and chassis there is still a drain on the battery. Leaving it weeks at a time without a charge you are probably reducing the voltage in the battery by a considerable amount. A chassis battery can only handle that so many times before it will not take a full charge again. While your coach batteries are made to handle that load better, they too will be reduced it just takes more time for them.

Also, please note that your keeping the coach plugged in all the time is great for the house batteries, it does nothing for the chassis battery. Perhaps getting a charge on that battery will help.
I actually do have a multimeter I can use to check the voltage. If I want to do a lot of swearing (it's really tight in the Vegas engine compartment), I suppose I could disconnect the positive cable, put the meter into ammeter mode and connect the probes in series with the battery post and positive cable to see if I can detect how much current is being drawn. Then again, that would only tell me there is a parasitic load, not where the load is.

Simplest "fix" would seem to be using the knife switch, which I may do within the next week or two.

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Old 12-16-2015, 02:22 PM   #10
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I had the chassis battery issue as have many. The knife-switch was the fix.

When I installed the switch I took a moment to stick an inline ammeter on the chassis battery to actually measure the parasitic drain. I don't remember the numbers, but they are posted here on the forums somewhere. What I can remember is that the drain is approximately 1 order of magnitude (10 times) what one would expect it to be.

All modern vehicles have a small drain to keep the various computers and clocks alive. Something else (perhaps many somethings) is sucking our batteries down.

Regards,

Randy
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Old 12-16-2015, 05:07 PM   #11
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I've not had a chassis battery discharge problem (knock wood) so the parasitic load causing the discharge must not be inherent to all Axis/Vegas. I do know there have been several with this problem though.
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Old 12-16-2015, 05:53 PM   #12
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Originally Posted by Larry
I've not had a chassis battery discharge problem (knock wood) so the parasitic load causing the discharge must not be inherent to all Axis/Vegas.
I didn't for the first 9 months of ownership either.
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Old 12-16-2015, 06:35 PM   #13
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Almost 18 months on mine now.
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Old 12-17-2015, 06:06 PM   #14
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I didn't for the first 9 months of ownership either.
Same here. We used it one time between the time we bought it and the time we drove from CA to ME. It sat for at least 2 1/2 months between the time of that single use and the time we drove to the East Coast.

Right now the unit is sitting in our driveway and I can keep it plugged in for the house batteries. We're on a waiting list for a storage lot within 3 miles of home. That would mean a complete disconnect from 120VAC and I'm looking at solar chargers for the chassis battery.

I have a workaround while the Vegas is sitting in the driveway. The generator really should be run every now and then. Leave it for much more than a week and it takes quite a bit of cranking to start. Every 2-3 days, I'm going to run a battery charger off an extension cord plugged into one of the outside outlets. It's not elegant, but it does kill 2 birds with one stone in that it will keep the chassis battery from dying as well as keeping the generator limber.

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Old 12-17-2015, 10:33 PM   #15
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I put a 400w solar charger, which actually takes care of the house batteries, while in storage, but if the chassis battery did go down for some reason, and I have never had that problem, but if it did I'd use the "e" button to give a boost from the house batteries. It's more important to take care of my houe batterires (at least to me), I have a 40a controller that has all four stages. I have 6v batteries wired in series of course, and I maintaine them. I also have the AGS system, when your generator is suppose to start up automatically when the battery gets below a certain voltage, but never had to test that feature with the solar on the roof.
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Old 12-18-2015, 02:43 AM   #16
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The dealer has had our Vegas since 12 Nov. Had a few warranty issues repaired and a windshield stress crack they are also replacing under warranty. Had to wait for the windshield to be shipped.

Had to stop at the dealer's to get a few things out of the RV for our trip in the car up to my son's in MD before Christmas. When I dropped off the RV in Nov I put the house battery switch in STORE. When they worked on it they putvthe switch in USE and left it there. When I picked up what I needed I thought I'd check the house batteries just for "giggles. Sure enough -- deader than a road killed skunk.

The service rep said they must have left the switch in USE. The windshield is being replaced tomorrow. We won't be back until 23 Dec. The service rep said they would ensure the batteries are charged when I pick it up on the 23rd.

You really do have to run the generator or plug into shore power at least 1 time a month to keep the house batteries charged. There was no problem with the chassis battery. Engine started right up. We rsn yhe engine about 10 minuted and it provided enough charge to the house batteries for the detectors to activate but not enough to start the generator.
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