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05-05-2019, 09:03 PM
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#1
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2018 Minnie Winnie 22M
Join Date: Sep 2018
Location: Sacramento, CA
Posts: 49
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Battery corrosion on coach batteries
I have a 2018 MW 22M that just spent October through April in storage under a cover. When I went to the storage lot and removed the cover on Saturday, I was showing my friend where the coach batteries were located, and upon removing the step cover, I was taken aback at the amount of corrosion that has happened to the batteries over the winter. I know they didn't look like then when I put the coach away in October, and my prior single battery rig never showed any corrosion at all. Of note, the last use last year was taking it in for its first service from the dealer I purchased the coach from, where I had it serviced while still under the one year warranty and then took it to the lot for storage. The coach was not connected to any power source for six months, and started while in storage twice.
Does anyone have any idea why this has happened and what could be the cause? I know the batteries were not overfilled at the beginning of last year. It looks like I have to remove the batteries and use baking soda to neutralize the acid, making sure the compartment is free of battery acid.
Thanks.
Lee
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05-06-2019, 07:24 AM
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#2
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Winnie-Wise
Join Date: Feb 2018
Location: NW Georgia
Posts: 358
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The rig has parasitic draw which has depleted the batteries charge. You are seeing the result. Normal. One way to prevent this is to disconnect the battery cables in long term storage. Another way is solar if the rig is uncovered to keep them charged. At this point they might need replacement if the plates are exposed, if not check specific gravity in each cell for a good idea. The other option is pull the batteries and put them on a small maintenance charger over the winter. Normally fully charged batteries in good condition will not create the mess you see.
__________________
Bill and Brenda + Mia
RIP Mobius - in our hearts
2018V24D, '13 Tiffin BR32, Tiffin 34TGA, '11 Aspect 30, 06View23H, '00 HHiker II 5W
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05-06-2019, 09:50 AM
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#3
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2018 Minnie Winnie 22M
Join Date: Sep 2018
Location: Sacramento, CA
Posts: 49
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Thanks for the reply, Bill. I’m still mystified over it all because the rig is only a year and a half old now. Last year’s storage produced no corrosion. I wonder what parasitic loads could have appeared over the year since the main power switch was in the off position over both winters. I’m not saying you’re wrong, but the conditions over the past two winters were identical but the results were very different. I will check the batteries, including the specific gravity when I remove them. Thanks again.
Lee
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05-06-2019, 02:05 PM
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#4
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Site Team
Join Date: Mar 2019
Location: South Bend, WA
Posts: 2,453
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I believe your battery was draining its charge over the top surface. I can see in your photo the dust on the top of the batteries, and that creates a sneak circuit. In your prior year of storage, the battery tops were still relatively clean, so no sneak circuit.
Aside from keeping your battery tops clean, if you could charge them once-per-month, that would be better. The battery chargers in the 2018 22M has a maintenance charging capability. You should be able to leave the coach plugged-in indefinitely, if that is an option at your place of storage.
To be 100% sure that your 2018 is like my 2019, just check the voltage after the rig has been plugged-in, with nothing having been run in the last 24 hours. You should see about 13.2 volts, which is a maintenance voltage.
__________________
2019 Minnie Winnie 22M on an E-450 frame
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05-06-2019, 07:09 PM
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#5
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2018 Minnie Winnie 22M
Join Date: Sep 2018
Location: Sacramento, CA
Posts: 49
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You know Bill, you might be right. When I showed the photos to my local Auto Zone manager, she said that the batteries looked awfully dirty. Well, they are exposed to the underside of the rig, and I did drive down some dirt roads last year, so I guess that they could get dusty and dirty that way. So, today I removed the batteries, removed the acid, tested them both, right at 12v, tested the gravity in each cell, and they seem good, but I’m going to take them tomorrow to be tested. Thanks for your help!
Lee
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05-06-2019, 08:36 PM
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#6
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Winnie-Wise
Join Date: Feb 2018
Location: NW Georgia
Posts: 358
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Right at 12.0 volts is near 40% SOC. It varies slightly with each battery, just pulled up the spec sheet on my T-1275 and 11.96VDC measured with a digital meter is 40% State of Charge. You probably already know that - just saying. Specific gravity of 1.148. You can check the spec sheet on your particular batteries but if they sit four or five months at that discharged state I would be thinking new batteries. All batteries have a self-discharge rate usually between 5-15% per month depending on temperature. Middle ground at 10% for 5 months is 50% down from fully hot batteries but at 12.0 you are 40% SOC (or my batteries would be). A good charge might work but sitting below 50% SOC is darned hard on them. For my T-1275s 12.5VDC = 80%SOC, 12.10VDC=50%SOC. Like I said it varies with battery so check your spec sheets on your batteries to know where you are. Generally speaking lots of corrosion like the photo tells me the batteries are getting near EOL. One of the worst things for a rig is sitting on a dealers lot for battery health. I've had to replace batteries several times on year old rigs, and sitting for service at a shop - they never think about the batteries.
__________________
Bill and Brenda + Mia
RIP Mobius - in our hearts
2018V24D, '13 Tiffin BR32, Tiffin 34TGA, '11 Aspect 30, 06View23H, '00 HHiker II 5W
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05-13-2019, 09:02 AM
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#7
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Winnebago Camper
Join Date: May 2012
Posts: 20
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Batterys
They make a paint to use on your battery posts once you have them cleaned up. It’s not prefect, but it helps You might also need to replace your cables as the corrosion can travel up the wires under the insulation.
Good luck, it can be a constant battle!
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05-13-2019, 11:04 AM
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#8
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2018 Minnie Winnie 22M
Join Date: Sep 2018
Location: Sacramento, CA
Posts: 49
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To Kayak73: Bill, you nailed it. I removed everything from the battery box, cleaned and neutralized the acid on the battery box, bracket that holds the battery down and the long bolts and nuts that hold it down in addition to the the one cable that showed corrosion. After cleaning and drying, I painted the areas where the acid took off the paint, let that dry, then put it all back together again. The coach master switch was in the “off” position, but when I made the final connection, SPARK! So there is a parasitic load on the batteries, even with the master in the off position! You were right. So next time in winter storage, either remove the batteries - a hassle, or at least disconnect them. (I used to leave the single battery in my old coach disconnected when in storage and never had a problem.)
I’ll say one thing: Winnebago doesn’t give much room in that battery box. I had to remove everything I could, including the rubber gasket around the top to barely get the batteries to scrape by getting out.
Lastly, I’ve checked the voltage on my old analog meter, and I now read 13 volts. So, maybe I’m lucky and the batteries were not destroyed over the winter. Hope not! I will also pay more attention to the condition and maintenance of those batteries!
Again, thanks for your help and the help of others.
Lee
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05-13-2019, 11:10 AM
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#9
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Site Team
Join Date: Mar 2019
Location: South Bend, WA
Posts: 2,453
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Hi Lee,
Just to be clear with the Parasitic Load, I was meaning the current load running through the dirt on the top of the battery. The spark you saw may have been from one side of a relay being energized. The switch which shuts-off all 12 VDC power from the coach is a light-duty switch, and cannot transfer the load of those two batteries, so that switch must be operating a relay.
Glad you have it all cleaned and ready to go!
Thanks, Eagle5.
__________________
2019 Minnie Winnie 22M on an E-450 frame
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05-13-2019, 11:30 AM
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#10
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2018 Minnie Winnie 22M
Join Date: Sep 2018
Location: Sacramento, CA
Posts: 49
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Eagle5, oh, no doubt about the relay. Clicking the on/off switch clearly triggers a relay with a loud "click" of a relay energizing. Maybe it was the dirt on top of the battery that allowed an electrical charge to go through it. Regardless, I'll pay more attention to it. My old rig, an 1978 Cruise Master that I had for 39 years wasn't located in a position where dirt could get it into it. The MW 22M has vent holes on both sides of the battery box below the step. Easy to get dirt in there!
Thanks again, and in retrospect, I wish I had that E450 frame as someday I want to have a dingy after my wife retires and we can go for much longer trips!
Lee
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