Dear Dave,
I have 5 AGM batteries in my newly purchased motorhome. Do I need to remove them for winter storage? I live in Colorado Springs and winters aren’t terrible, but it does at times get below O°. My RV is in a storage lot and I don’t have access to 120V. The Winnebago has a trickle charge solar panel, but I don’t know if that’s enough to keep my batteries from freezing. Thanks, Dave!! —Wayne, 2003 Winnebago Journey DL
Dear Wayne,
According to the Winnebago specifications, your Journey came standard with two 12-volt flooded lead acid (FLA) deep cycle batteries, which most likely were NAPA brand, and a 10-watt solar panel. This size panel was only able to provide a trickle charge to the batteries during storage to keep them topped off without anything else running.
You state there are five absorbed glass mat (AGM) batteries now in the rig, so a previous owner replaced the original FLA batteries with these. Most AGM batteries are a Group 31, which means more amp hours than the original Group 24 or 27 batteries. The 10-watt solar panel is not sufficient to charge two AGM Group 31, let alone five.
A 10-watt solar panel will only provide about 1 amp charging power, and it also depends on the amount of sun available to the panel. Typically you only get about 6 hours of sunlight exposure, so that will also limit the charging ability.
I would recommend replacing the 10-watt panel with a 100-watt panel, and a charge controller to regulate the charge. You will also need to verify the wire size, as the gauge may not be sufficient for the larger panel.
The challenge you will have is the wire is typically routed into the ceiling during the manufacturing process, so it will be almost impossible to route it through that. We did install a 100-watt panel on a 2003 Winnebago Brave that has a very similar roof structure. We routed the new wire down through the refrigerator vent and behind the refrigerator. The converter was located underneath the kitchen cabinets, so it was an easy install to the back of the converter. We mounted the charge controller on the panel just underneath the refrigerator.
If you don’t want to go to this extreme, I would suggest taking the batteries out and trickle charging them in your garage.
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RV’s house and chassis batteries drain fast during storage. What causes this?
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I went out to move the motorhome and discovered all three batteries were dead: the chassis (at 4V) and coach (both at 9V) batteries. The RV had sat for about two weeks (since last trip). We did not notice anything out of the ordinary when we had the RV out on our last trip. We were connected to shore power. The battery switches were set to “off” when we parked the RV at home. I currently have all the batteries isolated, hoping to see if I can recharge them one at a time and save them. Any ideas as to the cause? The RV is still under warranty but the dealer is 300 miles away. Thanks! —Jack, 2022 Winnebago Adventurer 29B
Dave Solberg is a leading expert in the RV industry and the author of the “RV Handbook.”
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I installed a battery disconnect switch as the battery shut off switch from the factory allowed some parasitic drain of the batteries. I have had zero problems with this system if I put my RV away with a full charge.
Am I missing something obvious here?
I wholly agree with Dave. During the winter – in south-central Texas – I put our small TT with its single AGM battery into dry storage while we live nearby in a much larger TT. Except for a few days, the temps remain above freezing. And the skies are more clear than not.
On the stored TT I switch the battery disconnect to eliminate parasitic battery drain and connect a 10-watt solar panel oriented to have an undisrupted view of the southern sky. The solar panel has a built in controller to trickle charge, float charge and desulfate the battery. But in no way could it simultaneously do this reliably for more than the one AGM battery.
AGM batteries hold their charge pretty well. Why not just every 4-5 weeks run the engine or genset for an hour, that would top off the batteries fine
Exactly, you should exercise the generator anyway about once a month, this will charge both sets of batteries, better than removing those heavy AGM batteries, hauling them home then taking them back to the storage lot and reinstalling them when you’re ready to go have fun. Evaluate all suggestions and do what makes you happy as all suggestions will work! Enjoy your new rv!