What Battery is best for my RV?

Golf Carts batteries typically are better and have thicker plates.

I decided to write this article because 75% of the people I help have the wrong battery for them installed in their RV. Your battery must state the AH (Amp Hour) capacity on the label or it is not a deep cycle battery. Most of these people went to an RV Dealer where they have a rack of batteries and you get to pick a pretty one. This article will help you find the best functioning battery for your RV, the way you use it.

If your RV is plugged in most of the time.

For people that keep their RV plugged in at RV park or home all most all of the time only replace battery when non functional. Try to find a battery with same physical size making sure to choose one with an AH rating on it. Each battery will have a capacity around 100AH. Scroll down to Brands.

Why is the RV battery Critical?

While boondocking our battery has many important tasks to do for us, some will be surprised how much we rely on them. The devices that require 12v power include Propane fridge controller, furnace thermostat and blower, lights, water pump, radio, move the slides, tounge jack, some leveling systems, many awnings and various others devices. Of course we can’t forget about starting the generator either, if you have one onboard.

Physical Size

This can be critical, your RV came with battery compartment or box and a venting system. It will be easier, but not always required to have your new batteries fit in same boxes. Flooded lead batteries will require adding water, checking the specific gravity and the venting system will have to remain functional. When measuring the battery box don’t forget to leave yourself enough height for connecting the battery terminals. If you decide to go with AGM or Lithium you have the ability to bypass the venting system, some mount them in living quarters for smaller temperature swings.

Types of Batteries

There are 3 main types of batteries, Flooded, AGM and Lithium in order of price. Flooded batteries are budget oriented and come with some Maintance and need to be vented. AGM is a sealed battery with no Maintance and more flexibility for mounting, no need to vent this type. Lithium can look more appealing than AGM with longer life cycles, more useable capacity and much lighter. The biggest downfall being temperatures below freezing. RV Battery Types – Lithium, AGM and Flooded.

Capacity of the Battery

Battery capacity is measured in AH’s. If your RV lights use 4A @ 12v and you leave them on for 2 hours (4×2=8AH) you will have used 8AH from your 12v battery. You will need at least 100AH of useable battery.

 VentingCapacity AHUseable AHWeight
Deep CycleYes1005060#
Deep Cycle GCYes1008070#
AGMNo10050 – 8070#
LithiumNo10010030#

As you can see from the chart above, the GC (Golf Cart) batteries and some AGM batteries can let you use more of the capacity. This is because these batteries are made with thicker lead plates.

Lithium is a separate group, it is the newest battery type with a lot of potential. They can achieve 2000-5000 cycles in a laboratory! If your leaning towards Lithium, more information here. Is Lithium Right for my RV?

The chart below is chart of Lifeline AGM battery in a laboratory at a constant 77 degrees. The curve of the cart in relation to DOD (Depth of Discharge) is similar with ALL batteries. Most boondockers will be lucky to see 1/2 of this life in the real world with temperatures being an issue and not able to charge the battery consistently because of cloudy and rainy days. When the expected life cycles of a battery is over it will not be able to hold 80% of rated capacity. An example of that would be a 100AH battery only able to yield 79AH of energy.

Battery Life Cycles
Lifeline Battery

 

Charging

If you are boondocking, you will be charging with generator/converter or with solar. The converter does not charge Flooded or AGM batteries correctly. How do I charge my RV batteries? It does not have the ability to adjust voltage to exact battery specifications or correct voltage for the temperature of the battery. Lithium will loose capacity sitting fully charged from constant converter charging.

Some out of the box ideas for charging batteries will include jumper cables from truck battery to RV batteries and an inverter powered by truck alternator/batteries plugged into RV shore power. IMO these are acceptable to get you by in a pinch.

How many batteries do you need?

Conservitive minds with daily use of 100AH believe you should have 300-600AH of battery capacity(180-360 pounds of lead acid batteries!) This will allow you to get through rainy and cloudy days with no issues. Most of the time you will charge your batteries back up with only using 10-20% of your capacity. This will get you batteries to last much longer but you will spend more on them initially. With lead acid batteries you will also get a higher self discharge ~.6% daily to figure in. Many will be ok without a generator with the bigger battery. This is uncommon solution for RV because of weight and space.

Liberal minds with the same daily use of 100AH believe you will be fine with 100-200AH of battery capacity. This will get still get you through a couple of cloudy or rainy days and generally will have a little more solar capacity. Some may need another way to charge besides Solar, have for this setup and the battery will only have to get you through the night.

Most people in an RV will lean towards the liberal mindset with weight, size and price being biggest factors. If you want to use inverter to run microwave or AC unit things will change drastically. Yes, you can run an AC unit in an RV, I can run mine all night on battery alone. This is not the common set up in an RV yet.

This is my typical useage in my ATC Toyhauler RV.

ATC 28′ FB 2018   
 12v AmpsHours runAH
Trace Current0.2244.8
Garage Lights – 6236
Kitchen Lights – 41.356.5
Entry Light – 10.310.3
Bedroom Light – 20.61.50.9
MaxxAir fan Level 10.140.4
MaxxAir fan Level 50.785.6
MaxxAir fan Level 103.226.4
Water Pump60.754.5
Furnace Blower7214
Awning Led Light1.155.5
12 volt Fridge *3.31053
Water Line Heater~3  
Fresh Tank Heater~10  
Gray or Black Heater~5 each  
    
Total AH per day  107.9
The first thing that sticks out is my 12v fridge consumption. This is not normal, the propane fridge will use 2-3AH per day.

Explanation of chart:

The trace currents could be propane gas detectors, a propane fridge (needs 12v to operate), thermostats or other devices that may have been installed. I would expect this exact current to be a moving target and be different on every RV. The number after the lights are the number of LED bulbs/pucks on each circuit, each bulb/puck seems to consume .3A. I have a 12 volt fridge that I installed aftermarket. Stock (from the dealer/manufacturer) is AC/ propane, which actually does needs 12 volt function. The heaters on my “3 season package” and the actual amperage used seems to vary and will depend on ambient temperature.

Once you take off the 53AH for the 12v fridge and factor in smart device charging and TV useage, this chart might be pretty close for most people.

Full Time Boondockers

For people off grid like me, the Battery, Solar and weather all have integral parts into the equation. I try to follow the 70 degree weather to keep my AC useage at little to none, plans of mice and men… The Battery has to be big enough to skip a full day of sun. The solar has to produce enough to charge the batteries in winter, with low and short sun days. Can you run AC from solar and batteries?

Battery Brands

A budget value lead acid battery is made by East Penn Manufacturing. They make Flooded and AGM batteries with Deka and Duracell brands Deep cycle batteries in Pennsylvania and Iowa. Trojan T105 Deep cycle batteries are a little more money with a tried and true great reputation. Trojan and Crown have AGM versions as well and typically will be twice the price of flooded version. Lifeline makes a industrial AGM battery that in my opinion is second to none. Rolls Surrette is in this elite class as well.

Lithium Geek Speak

The two main Lithium chemistries are Li-Ion (Lithium Ion) and LPF/LiFePO4 (Lithium-ion Phosphate. There are many more and there will be more to come before we find the Holy Grail of batteries. All Lithium batteries will need a BMS (Battery Management System). This will protect the battery from temperature and voltage. If this is not done correctly it can end with a junk battery or an exploding fiery mess!

Li-Ion can be found in our laptops, phones, cordless tools and most Tesla’s use this chemistry as it is significantly more dense at ~250Wh/Kg. These are made by Panasonic and LG and some are produced here in the states. This is the least stable Lithium battery and needs to be monitored well with a good BMS Tesla is leading the world here with their 21700 battery cell and their ability to manage temperatures of the 4,416 cells in their model 3. I could talk for hours on these batteries but I do not believe they are meant for main stream users (Yes my RV is powered by Tesla Batteries). I love watching Tesla and how they are changing the battery world as we know it!

LiFePO4 has a density of ~100Wh/Kg and this is what is used for RV drop in replacement batteries. All Lithium cells for RV drop in replacement batteries are made outside of the US and most/all come from china. This chemistry is much more stable but still needs a good BMS to protect it. BattleBorn is US company that assembles China sourced 26650 cylindrical cells in Reno. They have a good warranty but their business is assembling Lithium batteries and I wonder if problems surface with the technology if they could honor an abuncae of warranty claims. Trojan and Relion and Rolls ‘make’ a Lithium battery as well. These companies in my opinion are in a better financial position to honor warranties on the Lithium battery as it is not their only business.

Should you upgrade to Lithium?