The RV Battery: Our Definitive Guide

RV Battery
Portable Advisor

Your RV contains two types of batteries. There's the battery that starts the engine (starting or chassis battery) and the battery that powers your living space (the house rv battery). Batteries handle electricity and contain acid. Any time you handle these batteries you are putting yourself at risk.

Use this guide to learn how to manage both types of batteries to ensure your safety and to avoid the dreaded dead RV battery in the wildnerness situation!

Starting (Chassis) Battery Vs The House RV Battery

Starting Battery

The starting or cranking battery is so called because it delivers rapid bursts of mechanical energy in a short time period to start the engine. 

Tips For Prolonging Life Of Starting Battery

The starting battery will function like a regular car battery. It's charged by your alternator (an electrical generator).

If you're driving late at night and notice a dimming of your headlights, your alternator may not be working efficiently. It is important to pay attention to your alternator as its malfunction can lead to a dead starting battery and you stranded in the wildnerness! 

Heat is also hard on chassis batteries. A hot day and a hot engine have been the cause of at least one failed battery in our RV life! To reduce the risk of unintended boondocking, its worth remembering the following pointers:

1. Monitor the age of your battery. The best RV battery is the one you don't have to think about! You can expect from 3 to 5 years of regular, dependable use from your chassis battery as long as the charging unit works effectively.​

2. Review the function of your RV alternator. If you notice a sluggish starting pattern, your battery may be trying to say good-bye. If it's in warranty, you're in luck. If it's five years old, you're still in luck because you can change it out (or get your alternator repaired) before the battery checks out completely. The below video offers a super step by step approach to identifying alternator issues. The video looks at a car but the points are still relevant and effective for your RV.

3. Watch how your RV behaves under electrical load. If the lights are dim while you're driving at night, it could be that your alternator is not putting out enough current to keep your rv battery charged. Eventually, this will kill the chassis battery.

4, Get a multimeter to check your battery with the engine off and with the engine running. If your battery voltage goes up when the engine is running, your alternator is working and your battery is faulty. If voltage doesn't go up when the engine is running, your battery is working but not getting a charge from the alternator. You should also check out this video from Robert DIY who pinpoints when you have a battery problem as opposed to a alternator problem. 

How Starting Batteries Are Rated

One of the measures of a batteries starting power is the measure of CCA or Cold Cranking Amps. This measures how much current your battery will send out for 30 seconds before the battery reaches 7.2 volts while held at an ambient temperature of 0 degrees Fahrenheit. In a pinch, the CCA measurement may save you a lot of hassle by starting your RV engine.

House Battery

While chassis batteries are designed to release a large amount of charge to start the vehicle and then rapidly recharge, your house batteries are meant to release power slowly, drain well and recharge fully.

This type of rv battery is referred to as a deep-cycle battery and they come in two forms:

There is the RV Flooded lead acid battery and this can be checked and for charge, battery acid and corrosion and repaired if required.

Please note: anything that battery acid touches will soon have a hole in it. Don't do this work in your favorite clothes.

Flooded Lead Acid Battery Precautions

There are a number of precautions that you need to be aware of before performing any maintenance on these batteries which we have listed below:

1. Turn off all power headed into the battery and all power going out of the battery. Let your batteries rest for half an hour before testing them with your hydrometer

2. Lower the tip of your hydrometer into the cell and draw out enough fluid to float the reader inside the hydrometer tube. This tool measures the electrolytes in the water; the float has marks on it that will tell you if your battery has the proper level of electrolytes in the fluid. You want enough fluid to elevate the float but not enough to push the float into the top of the bulb, because then it can get stuck and won't float.

3. Check the cells to make sure they're not dry. Note that there is a fill line in these battery cells. Never fill a rv battery to the top!

4. Clean away any corrosion on the posts. Some corrosion-removing chemicals need to be rinsed away. Make sure to read the instructions before applying any corrosion remover.

5. Close up the cells. 

You can also purchase sealed or valve regulated lead acid batteries (VRLA). VRLA batteries cannot be opened for maintenance.

These batteries will reduce your maintenance workload but add quite a bit to your budget. Additionally, because they're sealed, you can't get inside to check the individual cells and plan for battery replacement.

Monitoring your house batteries is critically important to anyone interested in boondocking or dry camping, because your only other source of power is your generator and thus your fuel supply.

If you plan to spend most of your time in developed campgrounds where you have ready access to another source of electricity, the condition of your house batteries will still be important, but not as critical.

However, if your physical condition makes checking flooded lead cell batteries more of a hazard than it already is, go with sealed rechargeable batteries and budget to be sure you can replace all the batteries in a series if they fail.

Where Are My RV Batteries?

Your chassis rv battery may be under the hood, though depending on the size of your rig you may have more than one and your salesman or mechanic can help you locate them. Many Winnebago RVs store the battery beside the staircase just behind the front tire.

The house batteries on your RV can be stored in a variety of places. If you bought a used RV and the previous owners didn't access the battery, review all the storage areas for a removable or hinged panel.

Also, if your RV has steps built into the frame, check the facing panels or kickplates to see if they can be removed; your batteries may be under or behind the steps. Depending on the age of your RV, you may find an owner's manual on-line.

How To Test RV Batteries?

You can use a voltmeter to check both your chassis batteries and your house batteries. If your house batteries are sealed, the digital voltmeter is your best option for both types of battery. 

Set your voltmeter to Direct Current (DC) voltage mode and connect the red line to the positive terminal and the black to the negative. For a 12 volt battery, the reading should show between 12.5 and 12.7 volts. If the reading is below 12.5, you need to charge the battery.

Use the below video for guidance on using the digital voltmeter.

How To Charge Your RV Battery

House batteries can be charged by solar or by power from an outlet. If using outlet power, a 3 stage charger

1) Bulk, which gets your house batteries to 80 or 90$ of full charge.

2) Acceptance, which gets you to 100%.

3) Trickle, which keeps the power topped off. 

Please also note that campground power can be inconsistent. Monitor your voltage so you don't put your appliances in danger by trying to operate them at a low voltage.

If you're lucky, you'll just trip a breaker, but the wrong voltage can damage electrical appliances in your RV

Many motorhomes also have an onboard generator which will keep appliances, lights, air conditioning and fans working. However, if your fuel tank gets below 1/4, this generator will power down so you don't run out of gas.

Maintaining Your RV Battery - Our 10 Tips

1. Monitor the age of your batteries. Everything wears out; don't ruin good house batteries by wiring them in series with dying batteries.

2. Use a voltmeter to check your chassis batteries. If the battery reads healthy when the motor is off and bumps up in voltage when you turn on the engine, you're ready to travel.

3. For flooded lead cell batteries, monitor the electrolyte level and quality.

4. Check for failing cells by comparing cell power within one battery.

5. Safety first! Always wear eye protection and gloves when maintaining your batteries.

6. Invest in your own baking soda. The household cook will not be pleased to find their baking soda in the battery maintenance kit. Totally worth the money.

7. If your RV is going into storage, disconnect power where possible.

8. Never store batteries in freezing temperatures.

9. Don't store batteries on concrete abd keep away from moisture.

10. It takes longer to charge than it does to drain; be patient with your house batteries.

RV Battery Buying Tips

When you buy new batteries, get them from the big guys so you can get support across the nation. Save your receipts and all documentation so you can contact customer service if you've got a problem with a new battery.

Walmart stores are ideal for these purchases; you can find Walmart stores in every state and their return policy is excellent. Many RVers have had good luck with the Walmart Everstart Deep Cycle batteries. Take care to get the DC (deep cycle version) instead of the MS (marine starting) battery for increased performance. 

For new RV owners, taking a picture of the battery compartment and noting the measurements is a good idea. You need to know it fits before you pay for it!

If the battery doesn't offer at least a year-long warranty, don't get it. If the manufacturer doesn't rely on the product for a year, you shouldn't either!

Finally, if you've got 6 or 12 volt batteries wired in pairs or series, you'll need to replace the pair at the same time for best results.

Conclusion

If you can make battery maintenance a regular part of your RV life, you can avoid unpleasant surprises. It can also help to know when a battery is approaching the end of its life so you can budget and prepare to replace it.

About the Author Rick Rose

Irish-American husband, dad of three and gadget enthusiast! Sandy and I have been RVing since the mid-nineties after embracing the boondocker way of life. We now practice what we call the 'Portable Lifestyle' - the ability to ‘get up and go’ and explore new places throughout the year while maintaining our income.

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