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Wiring a Trailer With Dual Batteries and Solar Charger

Question:

HI, I have a new cargo trailer with a brake away battery set up. It has one LED light inside with a switch and one LED light in the third break light to light up the rear ramp, it is on a switch too. Lights are working only when the tow vehicle is connected to the trailer Here is what I would like to do. Add two 2 small batteries 12v 3.3 Ah total 6,6 Ah on the side of the tongue in a small battery box. Got those in place and secured. Add two 2 small 20w solar panels and a small solar charger/controller. Add few small LED light inside the trailer with a switch 3way, one at the side door and one at the rear ramp Add a back up camera to the back of the trailer to act has a rear view mirror, it will be always ON when the vehicle is connected to the trailer ONLY. What do I do with the BLACK wire from the 7 way plug. I am not sure if the two small batteries should be - grounded to the frame? Same for the LED lights about the -, to the frame or back to the solar controller? Should the batteries and new interior LED lights all be connected to the solar charger/controller on the load side. The two small batteries connected to the solar charger/controller. And nothing connected to the Frame - of the trailer . The only light to be connected to the Frame - and the BLACK + wire will be the RAMP light and switch witch are part of the rear third break. So, the 2 small batteries, the solar charger/controller, LED interior light and switches wont share the ground with the trailer. All the wires from the LED lights will come back to the solar charger/controller LOAD + and -. The 2 small batteries will go to the solar charger controller. I think the rear camera should be directly connected to the BLACK wire + and the FRAME -. And the video cable directed to the truck witch will share the - ground with the truck and trailer. Does this sound correct?

1

Helpful Expert Reply:

Let's try and take this one at a time to make things easier; to start with the black wire from the 7-way plug (the 12V) should be run to the pair of 12V batteries you already have in the battery box.

In terms of grounding they will be grounded through your Redarc In-Vehicle BCDC Battery Charger # 331-BCDC1225D.

The LED lights each need to be grounded to the frame of your trailer; they will also be connected to the 12V batteries which would be connected to the charger.

That covers the LED and the batteries which leaves us with a rear camera such as the Rear View Safety Backup Camera System # RVS-770613-213. On a system such as this the rear camera needs to be connected directly to the 12V power source (see cut out of the instructions that I added for you) while the wire is grounded to the frame, just like you said. You will need to use a Toggle Switch such as # PK34513 in order to stop the batteries from giving power to the camera at all times.

The instructions to the Rear View Safety System are also linked for you to check out and I've added a link to a help article on battery chargers which you may also find useful.

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helpful expert reply by:
1
Kyle S

Question:

Thank you. - To avoid the toggle switch , I will connect the back up camera on my running lights. I always turn them on when I have the trailer. - When the trailer is connected to the truck and it is not running keys off. - Will the battery from the truck discharge into the small batteries on the trailer? - Will the solar panels charge/maintain the truck battery? - Should I get an isolation solenoid on the trailer for the black wire and activate it with the a wire from the running lights lights. Thanks for your help.

1

Helpful Expert Reply:

When the trailer is connected to your truck but it is not running, and you have your 7-way connected, the battery from the truck can discharge into the small batteries slightly unless you have the BCDC charger connected which will isolate the starter battery to protect it.

If you use a different charger, then what you can do is use a battery isolator like the Deka 95 amp # DW08770 or 120 amp # DW08771 to charge the auxiliary batteries from your truck's alternator and prevent those batteries from draining the truck battery when your truck is off (when you remain connected).

Doing this means you won't need a solenoid; to install the battery isolators you are going to need the Deka Battery Isolator Installation Kit for Standard Alternators # DW08769 for standard, SI alternators which will have SI as the last two digits of the alternator's part number. The other install kit is the Deka Battery Isolator Installation Kit for Delco-GM CS Alternators # DW08768.

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helpful expert reply by:
1
Kyle S

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