A Dual Battery System to Boost Your Camping Power

If you have a caravan, Camper Trailer or RV you might often want to take it off the beaten track and get down and dirty with nature. I’m talking about the wilderness experience; selecting a campsite that offers little in the way of services – especially electrical power. In these cases you will have to rely on your battery power, and if you plan on staying a few days and still want the convenience of light, fans, radio and maybe DVD player, etc, you will need to boost your power reserves somehow and a dual battery system could be the way to do it. In this post I will summarise how I do it. It may not suit everyone’s needs or pocketbook, but if it gives you food for thought it will be a good start.

Some consideration needs to be given to a choice of battery. Deep Cycle batteries are not meant for heavy current drains but can be discharged to lower levels. These are usually found as auxiliary batteries in a vehicle or caravan. Also bear in mind that batteries do not like being discharged and will rapidly deteriorate if repeatedly discharged below about 50% of their capacity.

In my pop-top camper trailer I use two 120 Ampere Hour AGM batteries wired in parallel. This gives me at full charge, a usable 120 Ampere Hours (240 AH / 2). This preserves the life of my batteries and provides me plenty of power, plus a small margin if I need to in emergencies. The camper is fitted with a “smart charger” so that when I am connected to mains power the batteries will charge close to 100% capacity. I also charge the batteries from the vehicle alternator when traveling and this requires some safeguards – you do not want to discharge your starter battery below its operational level…

The diagram above shows my setup. For more detailed information, I have covered all installation details and background information in a 40 page How-To guide that you can access from here.. This document will provide you with valuable knowledge and information on this topic.

I have used this system on several occasions for extended stay camps and had plenty of power for lighting, water pump, radio/CD player, TV/DVD player and so on. You can work out your battery drain by identifying all the appliances you want to run, what their current draw is and then multiply that by the use time – example:

Lighting 2 Amps 20 hours
Water pump 5 Amps 1 hour
TV/DVD player 2 Amps 20 Hours
Radio/CD Player 1 Amp 20 hours

Total 40 + 5 + 40 + 20 = 105 Ampere Hours

Go take a peek at Dual Battery System – Fully Illustrated How To Guide. And if you want to know more about batteries in general see 12 volt batteries for camping.

Please Tell Your Friends

Filed under: General Tips, Smart Ideas

Recommended Reading:

Please note: All comments are read for approval before publishing. All spam is deleted permanently.

7 Responses to “A Dual Battery System to Boost Your Camping Power”

  1. pharmacy technician - May 5th, 2010 at 5:02 am

    Terrific work! This is the type of information that should be shared around the web. Shame on the search engines for not positioning this post higher!

  2. Scott - July 8th, 2010 at 3:30 am

    Great info thanks for sharing

  3. FredDespain - April 1st, 2011 at 10:50 am

    Well done. Thanks for the great post. Bookmarked

  4. Mike - June 26th, 2013 at 6:09 am

    Great article I do have a question on 2003 F250 i carry a Lance camper with one battery and a jeep trailer with a winch and battery hooked up to it. I used the standard 7 way charge line to connect the lance to the truck then plug into the camper then plug in the trailer and my charge line fuze blows. any advice? the trailer and lance battey are both hot do i need a relay or solenoid in betwen somewhere? Thanks Mike

  5. Terence - June 26th, 2013 at 3:06 pm

    Sounds like there is something majorly wrong here. I am not familiar with a seven way charge line, but I think you have a connection issue giving a short circuit. Both batteries being hot means that they are drawing excessive current with the result that your fuse is blowing.

    I would recommend getting an auto electrician to check out your set-up. If you want to try things out on your own make sure you always have a fuse in line for protection. I would check it out by using some thick cable to connect the batteries together in parallel (pos to pos and neg to neg – not forgetting the fuse). My preference is to connect with Anderson connectors. They are cheap and versatile.

    I assume your chassis grounds are of the same polarity. Not a lot more I can say without actually being there. Repeat: have a qualified auto electrician check it out. It will be cheaper than replacing two dead batteries.

  6. greg - June 28th, 2014 at 6:57 pm

    In the wiring diagram above I don't understand why you are using 100a fuses for your circuit protection. I would of thought you wouldn't exceed 50 amps due to the ratings of your Anderson plugs. Can u fill me in.

  7. Terence - June 28th, 2014 at 9:02 pm

    Hi Greg,

    The 100 Amp fuses are there to protect the cables between the batteries. If the pos and neg cables chafe and make contact with each other or chassis (pos cable), they can start an enormous fire. The 100 amp fuses will allow high currents through the cables up to 100 amps of course, which has been chosen arbitrarily for short circuit protection. This value of fuse seems to be the norm in dual battery systems. As for the Anderson connectors, they are rated for 50 amps CONTINUOUS current. They will handle occasional current surges over the 50 amps, but not continuously. Again, this connector is very popular and used in many dual battery systems.
    My choice has always been to think of a number (or calculate it in this case), Then double it for safety reasons. Overkill I know, but rather safe than sorry.


Tips and Techniques with SLR Photography