Ask Dave: Will my RV’s batteries freeze in cold temperatures?

Dear Dave,
My RV has two 6-volt batteries. Will they freeze in 32 degrees and lower? —John, 2004 Gulfstream 40 ft. Country Club

Dear John,
Yes, your batteries are flooded lead acid (FLA) and the electrolyte in the cells can freeze if the battery is discharged and the temperature drops below freezing. However, a fully charged FLA battery can withstand temperatures well below freezing. In fact, most batteries can withstand –80 degrees F before freezing.

State Of Charge (SOC)

A fully charged FLA battery should register 12.6 volts. I have written other articles about State Of Charge (SOC), which is a little confusing to some as a 50% SOC is actually 12.06 volts. Here is an SOC chart:

As mentioned, a fully charged FLA battery can withstand temperature down to –80 degrees F or more. At 50% SOC, it will freeze at 0 degrees F, and at 0% SOC, at 20 degrees F, and some even a little warmer than that.

If the liquid freezes, it will expand and can ruin the battery. It is best to fully charge the battery to 12.6 volts and use a trickle charger to keep it maintained. If you do not have access to electricity or solar charging power at your storage facility, it is best to remove the battery and place it in a garage or shed with a battery maintainer.

If the battery does freeze

If you experience a frozen battery, you may be able to bring it back to life with a little TLC. Do not charge a frozen battery; rather, bring it in to a warm area and let it thaw slowly. Visually inspect the battery and case for any signs of cracking or damage and check the fluid level. Then, after it has thawed, charge the battery slowly with a battery maintainer.

 You might also enjoy these posts from Dave 

• How to winterize RV batteries
• Follow-up to 12-volt roof air and refrigerator question. What are the best batteries?
• My RV’s “larger” batteries are dead. Can I replace them with lithium?
• Can different type and age RV batteries be mixed? Can I add a lithium battery?
• Will RV’s house batteries ‘play nice together’ if I replace chassis battery with lithium?
• Will my RV’s charger be sufficient for new lithium batteries?

DAVE HAS ANSWERED MORE THAN 1,000 readers’ maintenance and repair questions. Read a directory here. There is so much to learn!

Dave Solberg is a leading expert in the RV industry and the author of the “RV Handbook.”

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