Perhaps 50% of full time RV boondockers have two 12 volt batteries or two 6 volt batteries to power their DC accessories and appliances. This usually provides between 200 to 240 amp hours of power, which is plenty run just about anything within a 24 hour period with the exception of air conditioning units.
How Much Battery Power For Boondocking Will I Need?
While about half of all dedicated boondockers have 200 to 240 amp hours (AH) of battery power, there are others that go either bigger or smaller…
- Another 25% have four or more batteries for 400 AH or more. These people generally want to power their microwave oven on battery, but still run their air conditioning on generator.
- The other 25% have just a single 12 volt battery for 100 AH, usually what came stock with their RV. You can still boondock effectively this way, you just have to be more conservative with your electricity usage so that you can stretch your power through the night.
Some Things Don’t Run on Battery Power
Appliances that run on AC current (110V or 120V) don’t run on battery power. Hence, you don’t need to count them when determining how much battery power for boondocking you’ll need…
- Your air conditioner unit runs on AC.
- Microwave oven runs on AC
- Anything you plug into a wall outlet (hair dryer, toaster, coffee maker, TV, electric heater, phone charger)
However, many boondockers have added an “inverter” which converts battery power (DC current) into AC current. Then they add an additional AC outlet to a wall and connect it to the inverter. Or, the plug appliances directly into the inverter. If you don’t have an inverter, you’ll need a generator to produce AC current.
What Runs On Battery Power
Your RV will use battery power for overhead lights, vent fans, thermostat, water pump, tongue jack, awning, Happi-Jac bed, outdoor lighting, slide motors, propane leak detector, breakaway brake (on trailers).
There are also appliances that run on two or three different sources of energy:
- RV refrigerators use battery power for the control panel, but either propane or AC power for the cooling
- The furnace uses battery power to run its internal fan, igniter, and control board, but propane for the heater
- Your water heater uses battery for its control board, but either propane or AC power for heating
- If you have built-in generator (Onan) it needs battery to prime the pump and to start the engine.
The item you’ll depend upon the most is the water pump, because you won’t get any water from your water tank without it. You won’t be able to shower without it, and you can’t even flush the toilet without it. Your lighting will be next most important.
How Many Amp Hours (AH) Do I Need for Boondocking?
How much battery power for boondocking you will need is measured in Amp Hours (AH). This is a measurement of how much amperage a set of batteries can hold and deliver, expressed in terms of hours of use. Generally, the larger in physical size the battery, the more AH.
A typical car battery used for starting an engine has about 87AH. But most boondockers are using deep cycle marine batteries or RV batteries that deliver 100-150 AH each.
- 50% of the RV boondockers mentioned above, with either have two 12 volt batteries, or two 6 volt batteries. This typically gives them between 200-250 AH at their disposal. That’s still plenty of battery power to run a propane furnace all night long, keep the lights on in the evening, run the vent fans during the day, charge electronic devices, and keep the water pump ready for use.
- The 25% with four or more batteries, typically are running four 6 volt batteries, and usually have about 400-600 AH available. These boondockers often have a 2,000 to 3,000 watt inverter to convert DC power to AC, so that they can plug in popular appliances (blender, food processor, television, coffee maker, hair dryer, vacuum cleaner, et al) into a familiar wall socket. These boondockers are looking to have all the conveniences of a brick-n-mortar home in a camper.
- The other 25% of boondockers with just a single 12 volt battery, have only enough power to run their lights, fans, and water pump most of the day. A single battery won’t run a furnace all night long, and generally won’t even run it for more than a couple of hours. Hence, most boondockers in this category use a portable propane heater and lots of blankets.
You Can Only Use Half of Your Battery
Keep in mind that lead acid batteries, in either the flooded cell or AGM type, can only be used until it reaches 50% state of charge. If you continue to draw down a battery below 50%, it starts to suffer permanent damage. At that point, it loses its ability to recharge. Hence, a battery rated as having 100 AH, technically only provides 50 AH under proper use.
When a battery is fully charged, it generally delivers as much as 14.0 volts. By the time it reaches 50% state of charge, that voltage will drop down to about 12.0 volts. Once voltage drops below 12.0, your RV’s built-in lighting becomes dim, the ceiling fans might not even turn on, and the starter motor in your built-in generator may not even work.
This is Why Lithium Batteries Are Better
Lithium batteries are better because they can be discharged all the way down to 0% state of charge without suffering damage, and without suffering voltage loss. Thus a 100 AH battery will deliver all 100 AH without voltage loss.
This means you only need one (1) lithium battery to replace two (2) lead acid batteries. Lithium batteries also have a longer life span, as much as triple. Add to that the fact that lithium batteries weigh almost half as less as lead acid batteries, now you can really see the benefits.
The Cheapest & Easiest Way To Go
Buy two 12 volt, flooded cell batteries, with at least 100 AH each, and a couple of thick (0, 1, 2, 3, or 4 gauge wire) and wire them together in parallel (see diagram). And that’s it, you’ve joined the 50% category of boondockers. It’s about as plug-and-play as you can get, without taking on too much cost…
- Technically, wiring two batteries requires four wires, but your RV should already have two wires there.
- It’s important that you are using two batteries of the same age, brand, type and size. Even though your RV may already have a single 12 volt battery in it, don’t buy just one additional battery, buy two. Use your stock RV battery elsewhere (many boondockers use it as a starter battery for their built-in generator) or take it to auto parts store for the core fee refund.
Four batteries requires wiring two in parallel and another two in series, to get 12 volts. It’s a little more complicated, and the cost is quite a bit more due to the four batteries and cables. Four batteries also adds a lot of weight to your RV. It’s better to start out with two batteries, and determine later if four batteries is necessary.
For More Reading
- For a more technical analysis of how much battery power for boondocking you’ll need, the Boondoctor has an excellent article, “How Many Batteries Do I Need For My RV?“
- Thinking of going solar? Read our other article, “How Many Solar Panels do I Need for Boondocking?”
Your comment about wiring four batteries is misleading! If you are talking about 4 six volt batteries, you are correct. Two in series as a set and two sets in parallel. If there are 4 standard 12v batteries, they must all be in parallel or you will damage something when your two in series apply 24v to your 12v system.March 6, 2021 at 11:22 am