Twelve-Volt RV Circuits 101: Down To The Wire

You will want a removable fuse to cut down on any power drain when the battery is not in use. Generally, you will find the battery box located on the tongue of your pop-up camper. If you are running propane, then it should be right next to the propane tank. That is the common and easiest access point for owners.

Sometimes it is and to the chagrin of some owners, sometimes it isn’t. Then check to see if the battery you do get is charged or has not run out of life. As mentioned above, your RV coach has two separate battery systems, a 12-volt DC system and a 120-volt AC system. There’s also an automotive 12-volt system for starting the engine and running basic automotive functions, just as there is in your car.


In other guidance I have seen, fuses are recommended close to each positive terminal. Would fuses be a useful precaution and if so how large would they need to be to connect 2 X 110Ah batteries running lights and a TV in a motor home? I cannot see my onboard equipment drawing any more than 4-8 Amps. Could you advise on wiring – do I need to connect to vehicle earth at all, since it will effectively be a ‘stand alone’ system? And how do I connect the 3 components on my output panel? One cable split at the unit or individual cables from battery to each of the 3 components.

The batteries will be fine, correct the wiring and they will go on for a few more years yet. If you have a multistage smart charger its always a good idea to disconnect them and charge them individually every 12 months to make sure you can get the best performance and maximise their life. Yes, you will need to connect the earths for a stand alone system… you do need to follow any advice on the solar charger for connecting a second battery though. Alarm batteries are typically 17Ah, a leisure battery usually 100Ah, so about 1/5 capacity. Additionally they are designed for a tiny current draw over a long period, not short bursts of high current draw. Yes, a lot of people do have portable panels to augment a fixed panel.

Parallel Connection – Keeps the voltage the same but adds battery capacity (amp-hours) together. So if you have 2, 12-volt batteries with 80 amp-hours of capacity each you’ll still have a 12-volt battery bank but 160 amp-hours of battery capacity. You can join as many batteries as you want to each other, though you may need an RV battery box to keep your separate cells safe and secure. Two sets of batteries connected in parallel can be joined together to form a series power bank. Batteries connected in series cannot increase the overall capacity but only increase the overall voltage.

Lithium ion batteries may last for as many as 5,000 charge cycles, whereas deep-cycle batteries may only last for 400 or 500. Determining the true state of charge of an RV battery is difficult without a monitor. An RV battery monitor can tell you exactly where you stand, measuring the energy that’s flowing into and out of your battery as well as its state of charge or discharge. Consider removing your batteries from the vehicle and taking them home with you. Check the voltage every month and charge it if it falls below 80%.

Appliances such as radios, refrigerators, smoke detectors, and propane detectors consume tiny milliamps over time which can drain your battery. Just because everything is off doesn’t mean it doesn’t consume some form of wattage. Over time, flooded-cell batteries lose water with each charge cycle, and this water needs to be replenished. You must use distilled water to help reduce the chance of sulfation, or the formation of sulfate crystals that can occur when the battery plates are exposed to air. Check the batteries at least once per month, and ensure that they’re fully charged before performing the necessary maintenance.


I would recommend fuses are installed at the +ve end of each cable. The correct method of sizing a fuse it to rate it at the maximum or below the maximum rating of the cable. The fuses are there to protect the cables from overload. If your current battery is connected by a 4mm2 cable, then when adding a second battery it would be OK to use the same size cable.

Our diesel heater has also made getting up in the mornings so much easier because with just a push of a button, our van heats up in minutes. Check out our van life “Electrical System” category page for more similar content. Is needed for each device, simply take the total watts the device is rated for and divide by 12. Take the result and round up to the next size rated fuse.

7 – Add appropriate sized blade fuse into the correct slot in fuse panel. 6 – Crimp the other end of the butt connector to wire attached to selected 12v device. Once you have your materials & tools, below are the steps to connect your 12v devices to the 12v fuse panel. Once you have your materials & tools, below are the steps to connect the bus bars to the 12v fuse panel. 7 – Connect the other side of the battery monitor shunt to the negative bus bar.

When you notice this unneeded running of the water pump, ensure all the air is out of the lines by turning on all the faucets. Otherwise, you can run your house battery down fairly quickly as your water pump does use some amps stir dating mobile data and will drain your battery quickly. Not to mention it add heat and stress to your pump and can reduce its life of the pump. Connects the 12 volt battery to the factory harness on Coleman and Fleetwood pop up campers.

Having the USB as battery power makes sense, in my opinion. A hood fan is great for eliminating all that smoke while cooking. It is also great at getting that excess moisture out of your camper.

How Do I Charge My RV Battery While Driving?

Thanks a lot for this very informative post, I was able to reconnect my both batteries following your instructions and I have much better output and charging now. The same idiot replaced the 15 amp Fridge, 20 amp Leisure Battery and 20 amp vehicle battery fuses with 30 Amps. These on my Autotrail tracker are located in the engine bay. I have now replaced the 30 amp with the designated fuses – 15, and 2 x 20 Amps. All the battery interlink cables should be sized to take the same current. If you’re experiencing problems with your solar inverter shutting off, don’t worry – you’re not alone!

If you’re planning to do a lot of dry camping in your RV, choosing a battery that can withstand extended periods without being recharged is important. The best RV batteries for dry camping are deep-cycle batteries with a high reserve capacity. Lithium-ion batteries are also a good choice for dry camping, as they have a very low self-discharge rate and can be discharged and recharged more times than lead-acid batteries. Whatever type of battery you choose, ensure it is properly sized for your RV and its electrical needs. With the right battery, you’ll enjoy all the comforts of home even when you’re miles from civilization.