How to Fix an Overheating RV Battery


Let’s figure out how to keep our cool when it comes to overheating RV batteries. Whether you are a part-timer or are part of the full-time RV crowd, you’ve probably had to fix something on your own. Don’t be afraid to troubleshoot this problem yourself, before taking it over to the RV mechanic.

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How to fix an overheating RV battery? There could be several reasons your battery is overheating. After making sure your battery has the proper amount of distilled water, checking connections and components of your system is the first step, followed by running a voltage check. Diagnosing either a bad battery or a bad connection could resolve this issue quickly and easily.

Unless you are a professional, messing about with batteries, wires and electricity can be intimidating. This guide contains need to know tips and tricks to assure the safety of you and your rig.

How Do You Know If You Have an Overheating Battery on Your hands?

These are the signs that you should look for if you suspect your battery is overheating. Get all of your senses ready:

  • Have you smelled a strong sulfur-like odor coming from them? If it smells like rotting eggs in your RV, it may be a sign of overheating batteries. As a battery wears down, the acid may evaporate and emit an unpleasant odor.
  • Heard a boiling sound? Obviously, a boiling battery could be a bad sign. When the acid in your battery evaporates it may cause your battery to overheat or even boil!
  • See them swelling? A bad battery may begin to swell. Overcharging batteries can accelerate the reaction within the battery and cause the release of heat and gasses, which cause the battery to swell.
  • Notice steam coming out? Another signal of an overheating battery can be steam or smoke coming from your battery. Overcharged batteries can result in dead cells & release of gas. Use extreme caution when dealing with any type of steam or smoke, as it may be hazardous and flammable.

*Always wear protective gloves & glasses when performing maintenance on your batteries! Face masks are also recommended for instances where your battery is emitting hazardous gasses. And, of course, no smoking or open flames!

Why is My RV Battery Overheating?

Ok, so we know our battery is overheating. But what we don’t know is why. Several things can cause your batteries to overheat. Let’s go through a step by step diagnostic check to see if we can assess the issue.

  1. The very first step in this process should be done monthly as routine maintenance. Checking the electrolyte and water levels of your batteries, to make sure you don’t need to add distilled water. Never use tap water, as this may cause calcium sulfation. Leaving your vent caps on while charging, prevents water loss and boiling.
  2. Then it’s time to check connections. Check every wire and appliance connected to the batteries, looking to make sure all of the wires are in top condition. Frayed wires or loose connections can cause you major problems now & later on down the road. (A little RV humor for you!) It is highly recommended to keep these properly maintained.
  3. Check your charge controllers. Charge controllers often have a digital screen with temperatures and setting options. Whether you have a factory-installed unit, or an aftermarket control unit, you should still be able to get some helpful information from it.
  4. Read through your manual, to make sure you are using the correct setting, and if possible look for a temperature reading to more accurately gauge how hot your battery is.
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Are You Charging Too Much or Too Little?

Continuous charging of an already fully charged battery is not recommended. You have the power, use it! If you are using it, and still reading a full charge, perhaps you should check your charge controller system.

Undercharging RV batteries are also a common problem we face. Do you monitor your charge levels? If you do not allow your battery to recharge between cycles you could be draining it down too far. Which can seriously shorten the life of the battery.

Finding a healthy balance will help you get the most out of your purchase. A battery that is used to a 50% level every day will last longer than one that is allowed to drain all the way down to a dangerously low 25%.

A Road Trip to the Mechanic

If after a thorough run-through of the steps above, you haven’t been able to successfully diagnose the cause of your batteries overheating, perhaps it is time to let the professionals handle it.

There should be no shame in this, you have done all that you can do. Taking it to a trusted RV dealership, or mechanic will properly address & solve your problem, resulting in peace of mind.

While you are there, ask questions about what they found, and what advice they have for preventing this from happening again. The mechanic will typically be happy to explain what went wrong. Write it down & keep it in your logbook for future quick reference.

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Proper ventilation

Temperatures outside can have a negative effect on the life and performance of your RV batteries. But, temperatures inside the battery compartment can soar even higher with the extra heat given off in a small enclosed space. Giving them proper ventilation can prolong the years of use you get out of them, by allowing them to breathe.

Place batteries in an area that has vents installed, or gives them a decent amount of space to have circulating air. When possible, installing extra vents never hurts, but gives you further assurance of proper ventilation.

Draining the Life Out of Your Battery

RV owners know about “parasitic,” or “phantom” draining of batteries. Slowly draining the life out of your battery like a parasite. This is caused by appliances like your refrigerator, radios, clocks, and various other electricity-powered items that run constantly.

Allowing your battery to carry a constant load in addition to these parasitic drains can cause the cells to go bad, and result in overheating, which can be damaging.

Safe Storage

Planning on storing your RV? Get ahead of the future problems causing issues by properly preparing your rig for storage. As you are emptying your cabinets of food, and closing all the windows, add these battery tips to your to-do list.

  • Keep batteries charged. While in storage for long amounts of time, the power can drain from the batteries & damage the cells. Rendering them unusable when you pull the rig out for the following season. Using a battery maintainer will keep it at its healthiest level.
  • Fill ‘er up! Check the water levels before storing. I know you have been doing it ritually the entire season, but it is also important in the off-seasons.
  • Lube. As always, keeping your battery terminal posts properly lubed will prevent any corrosion from happening. Don’t have any battery lube on hand? A tablespoon of petroleum jelly on each post works, too!
  • Stop the freeze! If you are storing your RV in a cold space for the winter months, you may consider removing your batteries to keep in a warmer place. The water within the battery may freeze if temperatures drop low enough. If you decide to transport it to a warmer place, be sure not to store it directly on a cement floor!
  • Keep the heat out! Will you be storing your RV through the hottest months of the year? Your batteries can really take a beating in the heat, even if they’re not in use. Before storing them, check the water levels & give them enough surrounding space to breathe.

If you have the opportunity to stop by and check on your rig while in storage, it doesn’t hurt to do a quick walkthrough. Better to be safe than sorry. If you find any issues, you can stop prevent any further damage instead of waiting till next season when the problem may be worse and far more expensive!

Safe and happy travels, hope to see you out there on the road!

Diane Dee

Diane is a lover of all things travel. She and her young family wanted to explore North America from the comfort of their own home so they bought an RV. After fully rehabbing a 1994 Safari Trek, they set out to explore both Canada and the USA.

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