How Long Do RV Batteries Last?
The first concern of anyone considering boondocking in the wilds is “How long will my battery last dry camping?” In order to enjoy lights, refrigerated food, running water, A/C, or heat will require electricity in some form. When the RV is not plugged in, that electricity usually has to come from batteries.
Under normal use conditions – lights, propane refrigerator, charging phones etc and water pump, a 12v battery will last 2-3 days. This time can be extended by adjusting power usage, conserving water (not running the pump), shutting off lights as much as possible, or simply by upgrading or adding extra batteries.
Boondocking on Battery Power
Dry Camping (or “boondocking”) is the practice of rv camping without any hookups. All necessary services must be provided by the camper. Therefore, the camper must have the ability to both generate AND store electricity for their use. The power can be supplied using either solar power or a generator, and the storage is supplied by using batteries.
Most RVs come supplied with at least one battery from the manufacturer. While these batteries are fine for short overnight road trips or weekend camping trips, they typically are not capable for longer stays. If you want to make a regular practice of boondocking, a battery upgrade is probably in order.
Types of RV Batteries
Lead Acid Batteries
RV manufacturers typically use a lead-acid type of battery. They are comparatively inexpensive to other types, and are pretty reliable with proper care. However, there are 2 different uses of lead acid batteries in an RV that you should be aware of.
The first is the battery that starts your engine, and the second is the type that runs your 12 volt electrical system when you are not on shore power. These systems work very differently and require different batteries.
"Chassis" Type Batteries
The “chassis” type of batery is the type you will typically find used as a car battery or under the hood of a drivable RV. They are designed to store power and discharge it in a short burst (when starting the engine.) These batteries are also designed to NOT discharge very far or very often.
Unfortunately, because they are the least expensive type- RV manufacturers will also tyically install them into the 12volt power system for the RV. This is fine if you are only running on batteries for very short periods of time, like a few hour.
Deep Cycle Batteries
The 12 volt power system needs a different type of battery to run efficiently. These batteries are designed to provide power in lower amounts, over a longer period of time. They are discharged deeply (down to about 50%) and then charged up again. This cycle happens over and over again. If you are boondocking, the charge/ discharge cycle can happen daily. This type of battery is called a “deep cycle battery” due to the deep discharge.
In choosing a proper battery system for your rig, you need to know how much power you will consume in the course of a normal day. A little math will translate that need into required amp hours.
Deep cycle batteries are designated by “Amp Hours (AH).” The amp hours are the total amount of power you will get pulling a consistent number of amps.
For example, if you have a battery rated at 100AH, and your rig is pulling 5 amps consistently, you can expect to get 20 hours out of the battery. Since you can only discharge 50% of the battery to keep it safely working, you should get 10 hours of power before recharging.
Multiple batteries can be wired together in “parallel” to supply more amp hours depending on the power demands of the coach, and they will last for an extended period of time.
One common change that RVers make is to change from 12v batteries to 6v batteries. 6v Deep Cycle batteries are made for golf carts. These batteries are expected to have many, many discharge cycles and are designed to have a long life and higher amp hours than 12v batteries. They are perfectly suited for use in an RV.
When using 6v batteries, you simply “series” wire them together in pairs. This type of wiring in pairs doubles the voltage creating, in effect, 12v batteries with higher amp hours.
RV Power Consumption
Various RV appliances and electrical items use varying amounts of power. This list can help give you an idea of how much power you will need to live while off the grid.
Keep in mind that if you plan to use any of the usual 120v items on the list, you will need an inverter sizeable enough to provide the AC power you need. An inverter converts 12v DC (battery) power into 120v AC which is what normally runs through your outlets to power standard household items.
For instance, in our fifth wheel, we have a full sized residential refrigerator. It draws a tremendous amount of power. We have 4 6v deep cycle batteries wired in series and parallel, to provide enough power to run just the fridge 14-15 hours a day. We have to run our generator at least 8 hours a day in order to keep the batteries charged.
Just another pair of 6v batteries is enough to run the rest of the rig with ample to spare. Residential refrigerators are not the best appliance choice for boondocking.
Some typically AC appliances are made in DC (12v) versions for use in RV’s. For instance a typical RV refrigerator can run on either 120v electric or can be run on propane, which allows a great savings for boondocking. There are also a few 12v refrigerators available on the market if you wish to run the RV’s battery power to the fridge but do not want the inverter.
TV’s are also available in 12v so that you can stay on top of your favorite series or sporting events while on the road.
How Do I Charge My RV Batteries
Most RV’s come equipped with some sort of converter/ charger to power both the 12v system while plugged into shore power AND to charge the batteries. The best chargers for RV batteries are 3 stage chargers. Power sources for charging are typically generators or solar power.
3 Stage Chargers provide a BULK charge which charges the battery to about 80% at high voltage, an ABSORPTION charge, which charges the remaining 20% at a slower pace, and a FLOAT charge, which holds the battery at full charge.
3 stage chargers are designed to vary the current and voltage to best charge the batteries and keep them at their most efficient. The better they are charged, the longer they will live.
For providing power to charge the batteries, you will typically use either a generator or solar power.
In order to USE this charger, you will need a power source. Generators are by far the most popular way to charge the battery bank on the road. They range in size greatly so you can always find the right generator for your rig.
A good general rule of thumb is if you are running 20 amps, a 2000 watt generator will probably do you fine. If you are running a 30 amp rig, look for 3000 watts. If you are running a 50 amp rig, look for 5000 watts- but only if you insist on running 2 major appliances at a time.
With our 50 amp rig, we use a generator that delivers 30 amps of power and just use a reducer on the cord. The only reason we would need more than that would be to run both A/C units at the same time, or the microwave AND A/C at the same time. We just don’t do that. 30 amps is plenty.
There are different types of generators ranging from the (extremely expensive) onboard “Onan” type generators, to conventional (inexpensive and loud) models, to the newer inverters (quiet but more expensive than conventional.)
RV Solar 101
As the cost of solar power comes down, more and more people are switching their RV power system to solar.
According to Energy Sage, in order to generate and use solar power for your RV, you’ll need a setup complete with the following components:
- Solar panels
- A charge controller to prevent overcharging your storage system
- Solar batteries to store energy (common options are lead acid or lithium-ion)
- An inverter to convert DC electricity to AC electricity (occasionally pre-built into the solar battery component)
Can I Plug In My Camper Without A Battery?
Technically speaking, yes you can plug in your camper without a battery as long as you have a converter/charger installed. The converter will supply power to your 12v system while you are plugged in. If you only have a charger installed, you do need to have the battery installed.
That being said, if you take the battery out of your rig while plugged in, make sure the connectors are well insulated. There may well be power coming through, even if the battery disconnect is shut off.
Does My Travel Trailer Battery Charge While Driving
Most 7 pin connectors do have a “hot” lead that goes to your trailer battery and will charge it while you drive at a slow rate. Over the course of a long days drive, you may get a good enough charge to fill the battery. This method is not terribly consistent as the power being delivered will be driven by the vehicles battery needs.
Since the vehicle itself will be drawing power from the alternator as well as the battery, there is not a lot left for the trailer. This combined with losses from the long run and small wire typically found in the 7pin connector, this is not a reliable way to charge your house batteries.
A solar system, second alternator, larger wire to the 7pin connector/ batteries are all ways to help this method work better.
Figuring out the right power system for your off grid camping adventures does take a bit of planning, but done properly, dry camping can provide huge camping benefits to you and your family once you have the right RV accessories.