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What Size Battery Do I Need For My Travel Trailer?

Whenever you’re preparing for a vacation trip, it’s better if you’ve thoroughly prepared for it. Stack up on canned or longer expiry food. Check your RV AC unit, make sure the brakes are working, and your RV has good battery health.

While preparing for your trip, you cannot ignore the battery of a travel trailer. The battery is what will power appliances in your RV. The RV battery from inside lights will power everything to provide power to your chargers.

So, let’s find out what size battery do you need for your travel trailer.

Understanding RV Electrical Systems

When deciding what battery size is best for RV, you first need to know how RV’s electrical system works. You need to get one thing in your mind for a start, and you’ll never get unlimited electrical power in an RV. Instead, it’ll always be a ‘limited power’ that you’ll have to manage.

An RV has two separate electrical systems, a 120-volt AC system and a 12-volt DC system. The main power system inside an RV is the 12-volt DC system, powered by multiple batteries. It has a water heater, refrigerator, furnace, water pump, lights inside your RV, and other appliances.

Whereas an RV hookup plug or a generator powers the 120-volt AC system. This 120-volt system powers your daily usage of appliances. For example, it is powered by TV, kitchen appliances, smartphone and laptop chargers, and other appliances.

The batteries of an RV last as long as they can charge at once. If you don’t have a proper charging system for them, they can run out of charge.

Although this rarely happens with RVers, there’s a chance it might happen. That’s where the generators come in. These generators power up your AC appliances and charge the batteries in emergencies.

Choosing the Right RV Battery

RVs come with one battery, a deep cycle battery. This battery is used to power appliances in an RV. For motorhomes, there’s a need for a separate battery to start the engine. Hence, came the starter battery, with the motorhome’s deep cycle battery.

Deep cycle battery in the RV powers several appliances. The deep cycle battery powers lights, water pumps, refrigerators, etc.

The deep cycle battery is often portable; you can take it out or put it back. This makes it easier to change once it starts to lose its charge. They can recharge to provide continuous power to the RV. Unlike the starting batteries, you can discharge them deeper. This increases their functionality and allows them to power your RV continuously.

The RV batteries come in 2 configurations, 6-volt and 12-volt. The configuration by an RV is always 12-volt. For this, you can combine two 6-volt batteries in series to get 12-volts power. The 6-volt batteries are smaller, and you can move them easily, but they are more expensive than 12-volt batteries.

Calculate The Power Usage

How to find the individual power of each AC appliance? For that, you’d need a wattmeter. Then, connect a 120-volt appliance or your whole RV into the wattmeter for it to calculate watts per hour.

This will show you the watts used per hour. You can use it for appliances that draw a constant 120-volt current. With this, you’ll individually calculate the watts per hour usage of each appliance.

After the calculation, you need to filter the appliances that you’ll constantly be using. This way, you’ll find out the shore power needs. It will also show the amperage to start the air conditioner’s compressor. But mind you, you need to add the converter’s wattage into this too, to get an exact value.

When the wattage of the RV is calculated, sum it up to make a total. Now, remember, your RV DC system runs on a 12-volt DC system. So, you need to divide the total by 12, according to the Amp = Watts/Volts formula. This will give you a total of how many amps per hour your system would use.

Another device to calculate consumption is the Battery Monitoring System. On it, you can run individual appliances or all appliances at once to check the consumption. BMS usually has interactive screens, so you can go back and forth on it to get the amps value.

What Battery Size Is Suitable for my Camper’s System

Most RVs come with a pre-installed battery. This deep-cycle battery powers up your RV home. If you want to upgrade or replace it, now’s the time to go for a higher capacity.

Batteries come in various sizes, and you need to find out which one is suitable for you. For this, you need to use the guide mentioned above to calculate your system’s consumption.

If you calculated the consumption, you’d have an answer with amps per hour. Depending on your system, it can be anywhere from 5 amps to 20 amps. A battery with 100Ah capacity can power a 5 amps per hour system for 20 hours. At the same time, a 20 amps per hour system would work for 5 hours.

The capacity of a battery is known as amp-hour. This informs about how many amps a battery can deliver. There’s a simple rule with batteries, the larger the battery, the more AH it holds.

Now, on with the battery size suitable for you. To give you an idea, RV batteries deliver anywhere from 100Ah to 150Ah. Expert RVers often have two 12-volt batteries or two 6-volt batteries. With this, they have over 200Ah at their disposal. With 200Ah, you can run several appliances at your RV, even if you are off-grid.

This much amp hour is suitable for campsites or when you’re on the road. But when you’re planning a longer boondock, you need even more amp hours. That’s where 12-volt DC systems with 4 or more 12-v batteries come in. They have anywhere from 400 to 600-amp hours at their disposal. This gives them enough power to run inverters to convert DC into AC and plug appliances.

Types of Batteries

Now that you know what battery capacity you need, it’s time to know about their types. The batteries in RV come in three main types, Conventional Flooded Electrolyte, Gel, and AGM batteries.

Conventional Flooded Electrolyte batteries are the most common in RVs. These batteries need a regular check of water levels and need distilled water refill when needed. Another drawback with these batteries is they get corrosion around the terminal post. But these batteries are cheaper as they provide a good capacity at cheaper rates.

The acid in Gel batteries is in the form of Gel. They are leak-proof and don’t require any refill. The Gel batteries are designed for marine use as they support slow-rate charging and with lower voltage. If you overcharge them, you can cause permanent damage to these batteries.

The AGM or Absorbed Glass Mat batteries have a fiber-type mat in between their plates. It is soaked up to 90% in the electrolyte. However, the AGM batteries are more expensive than the other two.

They are charged like Lead-free batteries, but they won’t leak or have any water loss. Meaning these batteries are maintenance-free. Another useful feature of these batteries is in winter. They work nearly as fine as a typical battery in warmer seasons.

Important Tips to Maintain RV battery’s life

Once you’ve decided what size battery you want and its type, we’ve some tips for your RV battery.

If your system has 2 batteries, make sure that they are of the same brand, type, and size. If you already have one battery, you can either store it or take it to the store for a refund.

Maintenance of RV batteries is necessary. It depends on what type of batteries you have. AGM batteries require almost no maintenance. But if you have any other battery, it’d require weekly maintenance to make sure it’s up to the tasks.

When storing your RV for a longer time, check on your RV batteries more often. If you are stored for a longer time at lower than 50% capacity, it’ll damage them.


How to make your RV battery last?

You can perform routine maintenance and recharge them more often. Make sure that your 12-volt battery never gets below 12-volts. Remove any parasitic loads that are attached to your battery.

Why do I need a battery for my travel trailer?

You need a battery for a travel trailer because it will power tail lights, brake lights, electric wheel brakes, and more. If your trailer has such accessories, then it will be legally allowed on the road.

How many watt-hours does an RV battery have?

The watt-hours in an RV battery are calculated by a simple formula, Watts = Volt x Amp. We can find it out by calculating it ourselves too. We know that an RV system runs on 12-volt DC power. And let’s suppose your battery has a 100Ah capacity. So, 12 x 100 = 1200 watt-hours.

Do I need a deep cycle battery for my travel trailer?

The deep cycle batteries are essential for travel trailers. That’s because they provide power to your trailers for a sustained period. Deep cycle batteries are designed to discharge and recharge constantly. If you use any other battery type, they will degrade over time.


If you want to make longer trips, you might want to consider larger batteries as they can hold more charge. But if you want to go extreme, we recommend getting two batteries.

When getting a battery, make sure to consider all the types of deep-cycle batteries. Conventional flooded electrolyte batteries are cheaper.

Whereas the Gel batteries require little maintenance, but they get damaged if overcharged. AGM batteries are the best option in deep-cycle batteries, but they are more expensive than others.

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