How Many Lithium Batteries to Power an RV

Are you considering changing your old lead-acid batteries for something more modern? Or are you looking to add capacity to your camper’s battery bank without requiring extra space? If so, you may have heard about Lithium batteries and more specifically Lithium-ion batteries.  

Lithium-ion batteries offer a number of advantages over lead-acid batteries in your camper. They offer a much longer life up to 10 times. They are much lighter and you can actually get the same capacity of lithium-ion batteries at a quarter the weight of your lead-acid batteries. They are also much more compact and will take up less space.

Lithium-ion batteries are also much more efficient and will charge and discharge much more quickly. This makes them a great option for boondocking.

The last thing you want to be worried about when boondocking in your RV is if the batteries are going to hold up. This article will help you size a lithium battery bank for your RV. 

How Much Power do you need to Run an RV

In order to get to the number of batteries or the size of the batteries, you need to understand the power requirements of your rig. RV appliances consist of 12v appliances that run on DC power and 120V appliances that run on AC power. 

To understand your energy requirements you need to convert them to Watt-hours. A watt-hour is a unit of energy. 

1 Watt-hour is the amount of energy that is used by a 1-watt appliance over the course of 1 hour. It can also be thought of as the amount of energy that is stored in a 1 watt-hour battery.

To calculate Watt-Hours you simply take the wattage of an appliance and multiply it by the time you use the device. 

Appliance Wattage Usage (Hours) Daily Watt-Hour Requirements
Refrigerator 300 8 2400
Lights 40 5   200
Mini Fan 40   320
Electric Water Heater 1200 0.33   400
Laptop 60 5 300
TV 30 5 150
Water Pump 60 5 300

The total comes to around 4070 watt-hours. 

So How Many Lithium Batteries will you need

Some batteries may be indicated in Watt-hours and with that, you can easily match and get the number of batteries. If it’s a 1000 Watt-hour you need around four of them. 

Most batteries however are indicated in Amp-hours. Amp-hours is a unit of electrical charge. It is the amount of charge that is delivered by a battery in one hour.

To convert Watt-hours to Amp-hours you simply divide the watt-hours by the voltage of the system. If you looking to build a 12v battery bank this comes around to 340 Ah. But if you using solar panels you can actually use one 200 ah battery to run the whole system. We tell you how next. 

Charging a Lithium Battery with a Solar Panel

A lithium battery can be charged using 100% of its capacity meaning that you can actually use 200 amps to charge a 200 ah battery in one hour. However, this is not recommended and more likely use 50% or 0.5C to charge the battery n two to three hours. This will vary with manufacturers.

So with a 200 ah lithium-ion battery, you charge it in 2 hours with 100 amps and four hours with 50 amps. So to get the solar panel size you multiply the voltage by the amperage. A 12v solar panel will have an 18v voltage for potential voltage, therefore;

18 x 50 = 900 watts

You can use a 1000-watt solar panel or two 500-watt solar panels in parallel to charge the battery in fours. 

Because a lithium battery can also be discharged up to 90% of its capacity this means that you can use your high wattage appliances early in the morning and afternoon and a solar panel can fully recharge the battery in a few hours. 

What are the costs of lithium-ion batteries?

Li-Ion is still a new technology that continues to evolve, prices have been coming down but they are still quite costly. A 200 Ah Lead Acid battery can cost less than $300 but this can be up to triple the amount when you go for Lithium. 

A 200 Ah LiFePO4 battery retails from between $699 to $1000 on Amazon depending on the brand. Have a look at some of our recommended LiFePO4 batteries. 

Other Downsides to Lithium-ion batteries 

Some batteries claim to be drop-in replacements for Lead-acid batteries for your systems. But this may not be accurate. RV batteries and systems work on a 12v system which you will get on Lithium batteries.

Lithium cells have a rating of 3.7v and four cells will come to around 14V which can work in a 12v system. Also, the size of the battery may be the same or even smaller and fit right into where the old batteries were. 

But this does not mean that you can just buy the batteries and fit them right in and expect everything to be running smoothly. Replacing lead acid with lithium-ion batteries is not an easy undertaking. You may need to change some of your electrical system components for this to happen.

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