Help with dual battery setup in trailer

[Hudson]

Here's a pic of my rig and trailer for reference. I use the trailer to tow dirt bikes, but I'm slowly adding more adventure trailer capability. My Honda has a pop-top installed by Ursa Minor.

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I'm getting a National Luna weekender fridge and hoping to add a dual battery system to get me through longer weekends. Not enough room in the Honda's engine compartment or rear cargo space to add a second battery setup, so hoping to use the National Luna Power Pack setup, installed in the utility box of the trailer. I don't have room in the rear cargo area of the Honda, since the rear seats need to fold down flat for sleeping.

The idea is to run the cables from the main battery, underneath the Honda and out to the trailer hitch, then run another set of cables from the Power Pack (installed in the trailer's cargo box) to the hitch, then terminate both with a quick connect. When I am driving, the Fridge would run off the main battery (I had ursa install a 30 amp power outlet on the Honda), and when camping, I'd run the fridge off the power pack connector.

Some questions:

1. Anyone do this kind of dual battery setup before, where the second battery is located on the trailer? Any tips, impressions, warnings?
2. Since the trailer may get unhitched at times during camping (and also when stored) how to manage the ground connection? Should I ground to the trailer? Any concerns/issues? The trailer is all aluminum if it matters, and will also have a rototpax setup on the inside wall of the trailer to hold fuel and water containers.
3. What about the quick disconnection terminations? I was thinking of using Anderson plugs, but would appreciate feedback.
4. I assume that during storage of the trailer in my garage, I'd need to run a battery tender to keep the battery fresh.

Thanks for any feedback.

 

[elcoyote]

Some questions:

1. Anyone do this kind of dual battery setup before, where the second battery is located on the trailer? Any tips, impressions, warnings?
2. Since the trailer may get unhitched at times during camping (and also when stored) how to manage the ground connection? Should I ground to the trailer? Any concerns/issues? The trailer is all aluminum if it matters, and will also have a rototpax setup on the inside wall of the trailer to hold fuel and water containers.
3. What about the quick disconnection terminations? I was thinking of using Anderson plugs, but would appreciate feedback.
4. I assume that during storage of the trailer in my garage, I'd need to run a battery tender to keep the battery fresh.

Thanks for any feedback.

1. Your nose box is a good place for the second battery. Use a sealed valve regulated deep cycle AGM. Preferably your nose box is not so tight that it cannot breathe a bit.
2. Ground your trailer battery to the frame. Also ground your trailer harness to the frame. As you are using Andersen plug for charging, you will also have ground back to your charging source i.e. your vehicle battery. This triple combination will keep you out of trouble. Not a problem that it is aluminum.
3. The Andersen will give you a reliable;e connection and you will be able to run larger gauge wire. This will give you a more effective charge back system.
4. If you store your trailer for more than a few weeks at a time then it is advisable to use an on board charger designed for the battery. Many of the chargers on the market today from Noco and Guest are compatible with flooded, AGM and Gel batteries. For a group 31 battery I would recommend a 10 amp charger. Both the Noco and Guest units will allow you to keep the charger plugged in indefinitely and will not over charge your battery. They also contain other nice features such as self diagnostics and de-sulfating capabilities. Chargers cost a lot less than the battery they are taking care of and are necessary for getting good service life from the battery. In our experience, most batteries are murdered rather than die of old age.

 

[Hudson]

Thanks Mario

Appreciate the feedback, Mario (I may have chatted with you on the phone for this setup). I have a fair amount of room in the nose box, so "breathing" shouldn't be an issue. Will likely create a grommet entry on the nose box to let the cables come through.

 

[Hudson]

Following up this thread. I am going with the National Luna Power Pack and a Sears PM1 (their deep cycle marine battery). I'll terminate with Anderson plugs at the hitch, and store the battery box in the trailer since the battery weighs 70 lbs plus the weight of the NL pack, and my tongue weight limit on the element is 150 lbs. Looking at some smaller aluminum truck box containers to mount in the trailer towards the center/rear to balance the weight.

Mario was able to talk me through a solar setup too. AT makes nice adapters that allow you to connect a solar controller to the NL to charge the battery. I'll have to try this out initially to see what kind of battery life I can get, and will likely add a 80-135 watt solar panel if the need arises. All in all, a nice solution.

A few times during this quest, I have questioned my choice in vehicles. I have wanted something reasonably small, a daily driver for work most of the time with 20+mpg, but the ability to change stripes quickly and haul my trailer and sleep me and my family. No need for off-road capability, but nice to have AWD for the winter months. We'll see if the Element continues to be the right choice.

 

[Hudson]

It took a few months to figure this out, but here's the final write-up. Huge thanks to Mario and the team at Adventure Trailer for helping me think through the setup, and being super patient. As a retailer, they are unmatched in my experience.

First, I installed a Sears Platiunum P4 battery in the Element. It was a tight fit, but no mods (other than an aftermarket battery tie down) required. Next I had a local hifi shop run cables from the main battery to the back of the rear hitch. The cables were routed in the interior. The first time, they ignored mine and National Luna's instructions to not ground the negative terminal to the car, and had to redo the whole thing. But the second time worked fine, and they fashioned a nice mount for the rear anderson. I found a dustcover online at this place, which has great prices on Anderson plugs and accessories.



Next, I used the cable from the National Luna kit to run through the trailer, terminating the front with a 120 amp Anderson to match the hitch, and running the rear 50 amp red anderson to plug into the PPP.





Now the challenge was where to locate the PPP. I had purchased a Sears Platinum Marine AGM, which was quite heavy (70 lbs), making the nosebox of the trailer not an option (too much tongue weight). I also didn't want a huge tool box, since the trailer is pretty small and I want to be able to fit 2-3 bikes inside. After tons of online research, I found this aluminum dry box on Ebay, which at $180 was the cheapest option I could find that would fit the PPP and still have room for other goodies such as a Noco A10 amp charger and a solar controller.

The box is just fine for my needs, even if the hinges and such are not up to typical Expo standards. But it's light and watertight. First we installed the Noco charger, using a punch kit to make the insert for the Marinco outlet.

Now I can just plug in an extension cord to recharge the battery during storage or if I have a 110 outlet at a camp spot.



It was a tight fit with the PPP's width. To keep the PPP from sliding around in the box, and to limit the potential for water issues, a buddy used his table saw to plane some 2x4s to raise and brace the PPP, and they fit nice and tight.

But how to get the power cable into the dry box, and how to get the 12 volt and fridge cables out of the dry box? I settled on getting a hinged electrical access door I located at the local Platt's for $12. It required punching a 2 1/4" hole, and grinding out a section of the hinged door cover to let the power input cable exit without keeping the hinged door open during transit. It's not entirely watertight, and I am looking at adding a rubber sheet cinched around where the cables exit, plus will add a thick bead of silicone around the opening to keep water from entering.





Here's the completed install with the PPP inside:





I had a 1M section of battery cable left over and I made an extension cable with 50 amp Andersons. You can see that with the cables connected, it is a nice and flush, and when I need to move the box, I can quickly disconnect the extension cable and push it into the box.



Final shot of the box inside the trailer. It takes up very little space.


Last thing I need to do is think how I want to secure it. Ideally, I'll bolt it into the trailer from the inside using large Nylock washers, but I need to think through how permanent I want this box in the trailer. It is pretty heavy to move around, and I don't trust the side handles. Plus I need to install a more secure, lockable hinge.

I'll have to see how well this setup runs the fridge and accessories before deciding on whether to add a solar setup.

 

[jronwood]

Good thread, always trying to lean more about the "eletro's"

Jronwood