6 Reasons Your RV Battery Keeps Dying (with Fixes)


There is something undeniably rustic and thrilling about traveling in an RV. Nothing can throw a wrench into a road trip quite like an RV battery that won’t stay charged. Unfortunately, there are many reasons why your battery may be losing charge, and it may take some trial and error to figure out what the culprit is. However, there is no reason to lose hope because RV battery issues can be easily fixed!

RV Battery
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There are 6 reasons that may be causing your RV battery to keep dying, and they are:

  1. Sulfation
  2. Parasitic loads
  3. Self-discharging
  4. Overcharging
  5. Undercharging
  6. Lack of maintenance

There is no need to worry, though. Each of these issues can be fixed, and you can be enjoying the countryside again before you know it! Each battery issue comes with its own indications to look for and its own fixes.

1 – Sulfation

The number one cause of lead-acid batteries failing is the buildup of lead sulfate crystals on the battery. This is called sulfation, and it happens when a battery isn’t allowed to get a full charge. In these cases, the lead sulfate crystals build up and stay on the battery plates. If there is too much sulfation, the chemical to electrical conversion of the battery is affected.

Sulfation can also lead to the following issues:

  • Longer charging times
  • Excessive buildup of heat
  • Shorter battery running times
  • Much shorter battery life
  • Battery failure

Two types of sulfation can occur on your battery: reversible and permanent. Reversible sulfation can be fixed if it is caught early enough; however, permanent sulfation cannot be reversed. The main reason that you should never store your battery with an empty charge is because sulfation will happen.

The sulfation of lead-acid batteries is inevitable, but it can definitely be slowed. The main causes of sulfation are:

  • When a battery is overcharged
  • When a battery is stored above 75 degrees
  • When a battery is stored without being fully charged

How to Prevent and Fix Sulfation

To prevent sulfates from building up on your battery, you must make sure that your battery has a charge that will not drop below 12.4 volts when being stored. Additionally, there are anti-sulfation devices that you can purchase that can help to prevent and reverse sulfation by applying pulses to the battery terminals of a healthy battery.

However, since permanent sulfation damage cannot be reversed, it is important to properly maintain your battery in order to lessen the buildup of sulfates and prevent sulfation from becoming a major issue.

2 – Parasitic Loads

Parasitic loads are the different systems in your RV that are connected to your battery and draw power from it when they don’t need to. Once your engine is off, the alternator is no longer running, and anything still drawing power will take it from the battery in the RV.

Parasitic loads can cause the following issues with batteries:

  • Draining battery charge
  • Shortening the battery life
  • Making it difficult to recharge the battery
  • Sulfation

How to Fix Parasitic Loads

RV batteries fall victim to many parasitic loads because of the amenities found inside of modern RVs. Electronically run objects like refrigerators, microwaves, televisions, lights, GPS systems, cell phone charging systems, and more can all become parasitic loads when you turn off your RV.

Battery Voltage

If you suspect that your battery is suffering from parasitic loads, you can use a digital multimeter to test your battery. Once your RV’s ignition is turned off, you connect the digital multimeter to your battery, and it will tell you if anything is draining your battery.

After you’ve determined the presence of parasitic loads, you have to use trial and error to figure out what is actually draining your battery. You should take turns pulling out the fuses of different objects within your RV to see which one is draining the power of your battery. You won’t be able to avoid all parasitic loads on your battery, but you can eliminate the largest ones.

3 – Self-Discharging

Self-discharging is an issue that affects all batteries. This is not as much as an issue or defect as it is simply a characteristic of all batteries. Keep in mind, though, that self-discharge can be increased by poor battery handling, and the effects of it are permanent. Age, cycling, and elevated temperature will increase the self-discharge of a battery.

RVs use lead-acid batteries, which have one of the lowest self-discharge rates. They lose about 5% per month. However, after the battery begins to age, lead acid causes sludge to build up in the sediment trap that can cause soft shorts within the battery – leading to higher rates of self-discharge.

How to Fix Self-Discharging

Because self-discharging is a naturally occurring phenomenon in batteries, it is impossible to completely avoid it. But you can help to lessen the self-discharge that your battery experiences. One of the most frequent causes of elevated self-discharge is leaving a battery out in the heat. In fact, the self-discharge rate doubles for every 18 degrees Fahrenheit that the temperature increases.

Older batteries will typically self-discharge more because of their age, as well. Poorly manufactured batteries will suffer from high self-discharge from the beginning.

Deep Cycle RV Battery

4 – Overcharging

Overcharging is another common issue that causes batteries to die. It is usually caused by human error (using a battery charger incorrectly) or not having a properly working alternator to regulate battery charge. Using the incorrect charging voltage or leaving the charger connected to the battery for too long are both ways to overcharge your battery by using a battery charger.

Issues that can arise because of overcharging your battery can include:

  • Complete battery failure
  • The sulfuric acid and distilled water mix can begin to boil and cause the battery to overheat, become hot to the touch, melt, or swell
  • Flammable hydrogen can start to build up inside the battery’s sealed cells which can cause the battery casing to swell or cause gas seepage (once this hydrogen meets oxygen, it becomes very dangerous – one small spark can ignite the gases and cause an explosion)
  • Corrosion of positive battery plates
  • Increased water consumption

How to Fix Overcharging

You can test your battery to see if it is overcharged by using a digital multimeter. Connect the multimeter to the battery terminals while your RV is running at idle. A perfectly charged battery will be around 12.6 volts, which is considered fully charged at 2.1 volts per each of the six internal cells. When you begin to turn things like the air conditioner, lights, and radio on, the volts will rise to an average of 14 volts.

If your battery is registering with more volts than this, it is overcharging. You should check your alternator for overcharging. If you are charging your battery with a battery charger, use a low amp setting to apply a trickle charge and prevent overcharging.

A professional charging suggestion is to charge your battery only after it has used 50% of its total capacity.

5 – Undercharging

Like overcharging, undercharging can negatively affect batteries as well. This occurs when you do not let a battery return to full charge after it is used. Undercharging quickly leads to sulfation.

Issues that arise as a result of undercharging your battery are:

  • Sulfate formation on cell plates
  • Shorter battery running times
  • Complete battery failure

How to Fix Undercharging

Undercharging is just as bad as overcharging, and being smart with your charging can help to prevent it. Always make sure that you charge your battery up to its fully saturated charge before storing it to prevent the formation of sulfate. Improper charging is the biggest reason for the depletion of active material within the battery, which results in a shorter battery life.

6 – Lack of Maintenance

Batteries require maintenance in order to make them last. Improper battery maintenance can cause a variety of issues. Maintenance issues that are most important are acid stratification and surface charge.

Battery Maintenance
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Acid stratification maintenance requires making sure that the acid within the battery is equally distributed for overall performance. Surface charge issues arise because of the sluggishness of lead-acid batteries that can result in a heightened state-of-charge on the outside of the battery.

How to Fix It

Sufficient battery maintenance is important. Following these guidelines can help to lengthen the life of your RV battery:

  • Allow for a fully saturated charge of 14 to 16 hours in a well-ventilated area.
  • Don’t store lead-acid batteries without charge. Do not store them below 12V.
  • Try to avoid deep discharges because they result in short battery lives. If you are using your battery under a heavy load, briefly charge it during short breaks of 1 to 2 hours to help prolong its life.
  • Make sure to never let the electrolyte drop below the top of the plates. When plates are exposed, they sulfate and can become inactive. If your electrolyte is low, just add enough distilled water to cover the plates before charging. Once the charging is complete, fill the water to the correct level typically marked by a fill line.
  • Never add acid. This can raise the specific gravity level too much and cause excessive corrosion.
  • It is recommended to only use distilled or de-ionized water for your battery. Some places have tap water that is usable, but you should check before using tap water always.
  • A new deep-cycle, lead-acid battery may only be charged to about 70% capacity. You will format your battery by using it at this capacity for gentle use or loads for its first five cycles to lengthen the battery life.
  • Check the capacity of the battery before you purchase it. If a new battery has a very low capacity, it is not going to perform as well as those that are new with high capacity.
  • A standard automotive battery can’t handle deep discharges like a deep cycle or marine style battery. This makes deep cycle batteries a better solution for RV house batteries.

How to Properly Charge Lead-Acid RV Batteries

RV’s are built with the house electrical system in mind. For this reason they have multiple ways to keep the house batteries charged up for extended off grid use. The typical ways that an RV electrical system keeps the lead acid house batteries charged are:

Alternator

Whenever the RV engine is running the alternator is being turned which provides current and voltage to the RV’s on board charge controller. Whenever the battery charge gets depleted through use the controller senses that it needs to be topped up and provides the required charge it needs.

Shore Power

Whenever your RV is stationary with the engine is off and connected to external power like it often is at an RV park the battery is charged through shore power. Similar to the alternator the shore power also feeds into the charge controller which supplies charge to your battery when it is needed.

Generator

If you are off camping off grid (without shore power connected) it is common to have a generator to supply your charge controller with the power it needs to charge your battery. Most RV’s have onboard propane or diesel generators mounted below the chassis but you can also use an external generator to do the job.

Solar Panels

Solar panels are very popular for use with RV electrical systems. With solar panels mounted on your RV roof your batteries can be kept charged year round as long as they are not obstructed by sunlight. Even if your RV is sitting for extended periods the addition of solar panels can ensure your battery’s charge stays topped up at all times.

RV Solar Panels

The most effective way to extend the life of your RV batteries and ensure that they stay in proper working order is to maintain a proper level of charge at all times. The combination of all these methods will ensure that happens.

The Life Cycle of Lead-Acid RV Batteries

The life of your RV batteries will ultimately be determined by the way you manage the charging and discharging of them.

For example, if you make sure that your batteries never discharge below 30% of their maximum charge they tend to have a 50% longer life span than if they were to be completely discharged before being charged.

Another determinant of battery life is the surrounding temperature that it operates in. Mose lead acid batteries are happiest in an environment that remains between 50 and 75 degrees F (10 – 25 deg C). The longer the battery spends outside of this range the more it lifespan is affected. Both extreme heat and extreme cold can lead to a dramatic reduction in battery lifespan.

How to Store RV Batteries When They are Not in Use

RV batteries are not cycled consistently like car batteries because they can go months without being used. RVs are not commonly used all year round because they often sit inactive for the winter season. These periods of inactivity can wreak havoc on the life of a battery, so it’s important to know how to properly store your RV batteries when they are not in active use.

Some tips for storing your RV batteries during inactivity are:

  • It is best to completely remove your battery from your RV during inactivity, but if you cannot remove it completely, make sure to disconnect the appliances in your RV to lessen parasitic loads. Appliances like radios, refrigerators, smoke detectors, and propane detectors should all be disconnected from your battery. Make sure you also regulate any solar panels that you have and unplug any converters in your RV.
  • Check the voltage of your stored batteries monthly and charge them up as they naturally self-discharge. It is good to keep them charged above 80%.

When you take care of a lead-acid, deep-cycle RV battery properly, they can easily last up to 5 years!

RV Battery
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RV Battery Types: Which One is Right for You?

RVs need to have deep-cycle batteries because of the frequent and deep discharges and recharging that RV batteries tend to go through. Deep-cycle batteries come in three different designs: liquid electrolyte wet cells, gelled electrolyte, and absorbed glass mat.

  • Liquid electrolyte wet cell batteries are also known as conventional flooded-cell batteries. They have a good capacity for a low price. These batteries need to be filled with water periodically, or they can ruin. The battery terminals require regular cleaning, as well.
  • Gelled electrolyte batteries are also called gel batteries. They have a thick, gel-like electrolyte inside of them instead of water. They cost a bit more than wet cell batteries, and they tend to last longer.
  • Absorbed glass mat batteries, also called AGM or dry batteries, have their electrolyte soaked into the fiberglass matting that covers their lead plates. These batteries are maintenance free, cost more than the other batteries, and can be mounted on their sides.

In Conclusion…

Taking proper care of your RV battery is necessary in order to prevent the added expense of having to buy a new battery every year. Learning the typical reasons that RV batteries die and how to prevent it is vital to making sure that your RV is ready to run when you decide you want to take a road trip!

Sulfation, parasitic loads, self-discharging, overcharging, undercharging, and lack of maintenance are the usual suspects of battery death, but they are all relatively easy to prevent with regular attention and smart battery charging.

Beau

Beau is an electrical engineer with a knack for DIY repair and construction. When he's not tinkering with his projects he's on the road travelling and enjoying an exciting lifestyle with his young family.

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