Posted by: Mark Polk | 5:00 am

Polk’s Top 10 RV Battery Tips

This article pertains to deep-cycle lead-acid batteries used in RV applications. Properly maintained deep-cycle batteries should last for 6 or more years. Unfortunately some RV owners replace RV batteries every year or two. Extending battery life is not that difficult, it just requires some basic care & maintenance.

Today I would like to offer my top 10 tips to extend the life of your RV and automobile lead acid batteries.

Caution: Always keep safety in mind when working around lead-acid batteries. Lead-acid batteries contain sulfuric acid that is extremely corrosive and can cause severe burns or blindness. The hydrogen gas produced by lead-acid batteries during charging is very explosive. When you work around batteries you need to wear goggles, gloves and remove any jewelry. Do not smoke or use any open flames around batteries

Polk’s Top 10 RV Battery Tips

  • Routine maintenance and recharging a discharged battery as soon as possible will extend the life of the battery. The leading cause of dead lead-acid batteries is sulfation. When a battery is in a low state-of-charge, small crystals start forming on the plates (sulfation) and if it remains in this condition for an extended period of time, without recharging, the battery is ruined. Sulfation starts when a battery’s state of charge drops below 80%, or 12.4 volts. Recharging a battery in a timely manner helps prevent sulfation.

  • Never let a 12-volt battery discharge below 12-volts. That probably sounds funny, but a fully charged battery is actually 12.7 volts. When a battery reads 12-volts it is at or below a 25% state of charge. You can measure the voltage using a digital voltmeter. Measuring the voltage gives you a quick picture of the batteries depth-of-discharge, so you know when the battery needs to be recharged. Set the voltmeter on DC voltage and place the red lead on the positive terminal and the black lead on the negative terminal to read battery voltage.
  • Reducing the batteries depth-of-discharge increases the life of the battery. A battery discharged to 50% everyday will last twice as long as a battery cycled down to 20% everyday.

  • RVs have parasitic loads that can discharge a battery over time. Some but not all of these loads are LP gas leak detectors, the TV antenna power booster, clocks, stereos and appliance circuit boards. If your RV is equipped with a battery disconnect switch make sure it is in the “off” position when you are not using the RV, or when it is in storage.

  • Hot temperatures and overcharging will kill batteries. During hot temperatures and during periods of high usage check water levels in batteries more frequently. Checking the electrolyte levels and adding distilled water as required can save your lead acid batteries.
  • When you add water to a battery use mineral free water. Distilled water is best. Regular tap water can cause calcium sulfation.
  • Properly charging your batteries needs to be done in stages. A bulk charge should be performed to return the battery to 90% of a full charge during the first couple hours. An absorption charge is used for the remaining 10 percent to prevent any battery gassing and loss of water, then a float charge to maintain a full charge. Lots but not all RV converter chargers are three-stage chargers.

  • Batteries should only be watered after charging unless the plates are exposed prior to charging. If the plates are exposed add enough water to cover the plates and then charge the battery. When the battery is fully charged fill each cell to the bottom of the vent well.
  • To prevent water loss from bubbling and gassing leave the vent caps on batteries while charging.
  • The lead and plastic used to construct batteries can be recycled. More than 95% of all battery lead is recycled. Make sure and recycle your old batteries.


For more information on caring for lead acid batteries check out our RV Battery Care & Maintenance E-book Course

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Happy RV Learning,

Mark Polk
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