Is a Lead Acid Battery Needed When Winterizing RV in Cold Weather

Updated 10/20/2026 | Published 10/14/2026

Products Featured in This Question

Replacement Fabric for etrailer Slide-Out Topper - 90" Wide - 4-Layer Vinyl - Black

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$86.99

50A Transfer Switch - Metal Box - 120V/240V AC

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$231.69

Question:

To your Victron specialist- Last Spring I purchased a Victron-II 2x120V from you, I connected to 2 Renogy Lifepo4 batteries. Installed and worked great all year as desired. My question, I live in Minnesota, in preperating for 3-4 months of below freezing and 2-3 weeks of bellow zero. In winterizing, Im going to remove the batteries and move inside to avoid damaging the batteries. My problem, when I shut down the Victron while the RV is connected to shore power I loose AC power throughout the RV cabin. I do not need or want it to invert battery power into AC and a really do not want lifepo4 batteries charged since they will not exist since charging below zero will damage the batteries. I need the MultiPlus-II 2X120V to pass through the shore power while the inverter is off. The manual does not give me any assistance. I need AC power inside the cabin, I trickle charge the chassis battery on coach power, I place 120V lights inside for the rare times I need to go inside. Please advise... yes I know a solution is to buy a cheap lead acid to sub for the Lifepo4 batteries. Ive spent enough...Thanks

asked by: Michael R

Expert Reply:

Hey Michael, welcome back! You do not necessarily need to purchase another battery but there isn't a super low cost solution. A correctly installed AC bypass switch would provide the winter-storage functionality you're looking for without requiring the Victron to operate without batteries. For a 50 amp transfer switch you can use the part # PD52. Which again you might just consider a super cheap lead acid battery.

expert reply by: Jameson C

Michael R.

10/20/2026

Hey thanks for the reply, But... I purchased the Victron II because it had a biuilt in transfer switch. I assumed it would default to pass through the electricity when turned off. Well, that's what I get for assuming, a mistake. Your suggestion requires additional wiring, I had my fun with that earlier this year. I was hoping there was a setting that I was missing that would allow the V 2x120 to pass through the 120vac power. thanks.

Jameson C.

10/20/2026

@MichaelR I completely understand not wanting to add more wiring after already completing the installation. There is actually an option that may accomplish what you're looking for. The Victron MultiPlus-II 2x120V has a Charger Only switch position that allows shore power to pass through to your RV while preventing the inverter from drawing on your batteries to supply AC power. The unit does need to remain powered on in this mode, so it isn't quite the same as having it completely turned off. Unfortunately, there isn't a setting that allows AC pass-through when the unit is in the OFF position. If your main goal is simply to use shore power without having the inverter operate, Charger Only mode should do exactly that without requiring any additional wiring.