Trojan 6 Volt Batteries RV Install

I added to the standard 12v deep cycle battery that came with the RV with 2 of the T-105 Trojan Six Volt golf cart type batteries. This update more than tripled my amp hour capacity from 85 ah to 310 ah and gave me a very robust dual battery bank system.  Maintenance is very easy just pop the caps and check the water levels periodically and top up with distilled water when needed.

In the 2 years, I’ve had the batteries I have only added maybe 1/2 a cup to each and that is using them full-time. They are a little more costly than some deep cycle batteries, but I believe the quality and longer life is worth it.  We boondock often and there is nothing worse than waking up in the middle of the night with weak batteries causing the furnace not to run.

I power a 1000w True Sine wave inverter  with the batteries for off grid power and use it to run our iMac computer and LCD TV with never a hiccup.  The combo provides us with clean stable AC power while we are off  the grid.  Usually can go 3-4 days between generator recharges unless camping in very cold conditions which cause the furnace to run more.

Here is my video explaining my Trojan 6 Volt Batteries RV Install


Overall I’m really pleased with the Trojan 6 Volt Batteries RV Install and would recommend them to anyone looking for a little more off-grid capacity.

Blue Sea Systems m-Series Battery Switches
Price: $27.99
You save: $2.96 (10 %)
29 new from $27.990 used

 Subscribe to the Monthly Newsletter!  Receive my eBook “Tips for the RV Life” as a gift to you.

RV Battery Addon Mod by Love Your RV! - #RV #Mods

Share this post with other RVers, thanks!
  • Paul

    Hi Ray, Love your guy’s forum and photo guides. I have a BigFoot camper on the back of my F350. I have had it a year and its time to get an inverter installed. Most of my questions have been answered reading your battery install and the solar install. The one question I still have is in regard to charging the batteries from the truck while driving. Did you put in new wiring from the alternator? Or do you only charge from generator or while plugged in or now from your solar?


    • Thanks! It charges through at 12 volt supply in the 7 pin trailer power cable built into the OEM truck tow package.

      • Paul

        OK. Mine does too. I don’t have a good meter on it so I can’t tell if we are getting back to full between stops. With the inverter we will be adding some larger appliances such as a coffee maker, MifFi/WiFi and maybe a microwave, so we will need to monitor the power more closely. Eventually we will add solar but for now we tend to move every couple nights and have never run into problems.

        Thanks again.

        • Ya, it’s nice with the solar as it adds to the regular truck charging when driving. Gives the batteries a great charge up if we are doing a decent amount of miles. Cheers.

  • Dick Savidge

    Ray, we would also like to use our 12 volt deep cycle wired to 2 6 volts. Can you tell us if you use 1+2 and if so does that wear out the 12 volt? Our mechanical engineer friend said this to us when we asked what he thought about this:
    A single 12V battery of the same physical size as one of the 6V will have 1/2 the size of internal plates as the series of 2x6V batteries. This is why 2x6V batteries in series will have about double the amp-hrs capacity of the one 12V… the resting voltage, internal resistance and discharge rate of the single 12V will be different than the 2x6V batteries… Meaning if he ever uses the 1+2 battery switch, essentially placing them in parallel, when charging and/or discharging, the single 12V battery could be stressed beyond specifications and will almost certainly shorten it’s life and/or cause it to fail early.

    We are curious to know what your experience has been with your set up. Do you use all three batteries at once an if so has it caused the 12 v to shorten its life, experience is what counts. Thanks.

    • Hi Dick, I mainly use the system switched to the Trojan six volts and keep the 12 volt battery in reserve. I charge them as separate banks. So I don’t use them all at one time 1+2. This was a way to use the existing OEM 12 volt battery since it was brand new for something useful, when I upgraded to the Trojans. I have also heard that mixing batteries is not a good thing for them. When I get a solar system in the future I will likely swap them all out for 4 new six volts wired as one bank.

      • Dick Savidge

        Ray, thanks for the clarification on the 6volt and 12volt. We went ahead and pulled the trigger on 2 more 6 volts since we were just starting the process. Now we could use some direction on inverters. We have a cigarette lighter inverter, can we re do the wires and use that? We are looking at microwave and blow dryer worst case scenario, apple devices best case scenario:-). Also, I am a complete newbie when it comes to how to wire this in and where the the wires should go to power the whole house? Any direction you can point me in would be great. Kind of at a loss as to this inverter thing.

      • Dick Savidge

        Should have added that the inverter I have is 700 watts

  • Mike Williams

    Hooked up 2 6 volt deep cycle batteries in series. Everything works like normal except the holding tanks(water, sewer, propane) stay fully lit at all times saying they are full. Any ideas as to what I may have hooked up wrong?

    • I would look for a pinched wire somewhere. Won’t have anything to do with the batteries if your getting 12 volts. But maybe during the install a wire in the display circuit got pinched and is grounding the circuit.

  • Bought a used Rv it has 4 6 v batteries hooked as two twelves I think, how do I charge them all at once ?

    • They should be hooked up like this, attach the chargers leads to the input + and – wires. You should be able to just plug in the RV to AC power and the onboard charger should do the job for you if they are already hooked up properly.

      4 Six volt batteries wired for RV



    • Sometimes those meters are not accurate, check right at the batteries, should read 12.8 volts with no load when fully charged.


    Could you explain how you connect the inverter output? Also do you somehow disconnect the Orginal equipment inverter?

    • Hi Jerry, my RV didn’t come with an OEM inverter, just a converter. I hooked the output from my inverter through a armor shielded wire into a dedicated AC outlet near my entertainment area, if I need AC anywhere else I just use an extension cord. This keeps my inverter circuit separate from the rest of the RV electrical. Another option is to use a transfer switch and hook into the RV circuits, I chose to just keep things simple. Works for me. Here is an blog post I wrote showing my inverter hookup –

  • Carol


    We have the same batteries but I cannot find the correct size box for them that will fit in our trailer. Where did you get the white box for yours?


    • Hi Carol, I found mine at a local battery sales shop in Victoria BC where I purchased the two Trojan batteries. I have seen them online –,576.html
      You also might check at places that sell marine stuff, many boats use the same type batteries and boxes as RVs.

      • Carol

        Thanks! The website looks like what I need!

  • Wade

    Hi Ray, I installed my mini Blue Sea switch much like your design between 2 banks of 6 volt batteries. Thanks for your video! BTW, I thought the switch was broke as I had everything hooked up (including truck!) but I couldn’t get the DC power switched off. I rechecked everything and everything was connected fine. Perhaps switch is broken. I left the project alone for a bit. As I sit watching tv It hit me, the truck was connected!! *#^*! Disconnect truck, all is well!

    • hehe, sometimes we get so wrapped up in a project we over think things, overlook simple stuff. Glad you got it all setup, happy my video helped 🙂

      • Wade

        The Living Forest is awesome!

  • John

    When I first purchased my first 5th wheel trailer. I replaced the one 12 volt battery with 2 6 volt Trojans, I have never had to worry about running out, do primarily dry camping.

    • Wade

      Hey Ray, me again, I was wondering with that battery switch in the 1&2 position, are you getting 12 volts or 24 volts? I would imagine its only 12 volts as it looks that the two 6’s and one 12 are in parallel with other. Thanks

      • Hi Wade, Yes I get 12 volts. The batteries are setup with the 2-6 volts in series then that is parallel with the single 12 volt. You would never want to have 24 volts as it would likely damage circuits in the RV.

        BTW I started a community site for RVers at Come join up!

        Cheers Ray

  • Bob Perry

    Ray…I’m trying to hook up 4 Trojan T105s and was wondering if this is over kill? We have not done any boondocking yet and are unsure how much we will do. I was told if you go with the new six volts it is better to go all new then add later as the chain is only as strong as the weakest link. So if one battery is bad then it will draw down the other to its level. That’s the reason I am looking at 4 new ones now. I currently have a 12volt which I have no idea of its age. Also my intent is to go solar down the road as well. What is your suggestion?

    • 4 – six volts is a great sized battery bank, if you do any boondocking at all you will appreciate the extra capacity. I say if you have the space go for it. Also with 4 you’ll be able to run a good sized inverter, like 2000 watts without any problems.

    • Four 6V batteries are not overkill, particularly if you use a lot of power. Both of my previous RV’s had just a single 12V battery and it was surprising how quick you can drain one running the lights and appliances. Cold weather and a furnace fan can really run them down quick, too.

      My current RV has four 225Ah 6V batteries and they make a huge difference. I went from charging after two nights, to no worries.

      The other thing you might consider adding, especially if you’re going solar, is a good battery monitor. I have a Xantrex LinkPro ( ), but if I were to do it again, I think I’d go with a Trimetric ( The Trimetric has more features.

      Battery voltage alone isn’t a good measure of remaining capacity. If you’ve got a solar panel artificially keeping voltage high, it becomes even less useful.

      A battery monitor will monitor all the power going into and out of your battery pack, as well as the temperature and voltage. This will give you a much more accurate picture of what’s going on with the pack and how much power is remaining. Generally, they give you a readout in either percent remaining, A/h remaining, or in some cases, how long you can run at the current discharge rate before the batteries are exhausted.

      Additionally, knowing how much your RV is drawing at any one particular time can be really useful for understanding the energy “cost” of a particular system. Check the energy draw of the RV, turn on a system, check it again and do the math to understand what that particular system uses. Example: My RV had incandescent globe light bulbs surrounding the bathroom mirror. Turns out, they draw a LOT of power, about 5A. That’s 4x as much as the florescent light in the ceiling of the bathroom. So, we favored the ceiling light when boondocking and saved power. Since then, I’ve replaced the bathroom lights with LEDs that draw significantly less than even the ceiling light and our preference has shifted again.

      • Thanks for the very informative comment Eric

  • Bob Perry

    Great article and Video … A picture is worth a thousand words