Mobile PV Solar Panel for RV Storage Lot

[AKGperson]

I just purchased a Coleman 30 watt PV panel so I can keep my batteries (2 - T145's) topped off in storage. I'm thinking of mounting the panel and charge controller on a piece of plywood that I can sit beside the TT because I don't want to modify the TT. I'll disconnect the panel and leave it at the storage lot when I'm camping. Any suggestions on a good controller and setup?

Ken

[Mustang65]

When you hook up your system, pull your main 30 amp fuse by the batteries or if you have one turn off your battery disconnect switch. This will eliminate the loads from inside the TT.

I looked up the specifications on that Coleman 30 watt PV panel and it shows a voltage of only 12VDC. I could not locate any max voltage for this panel. If it is only a max of 12VDC, then your batteries will not be topped off, as fully charged battery is 12.6VDC and be able to keep the battery 13.2VDC. A SOLAR panel that is used to charge/keep topped off, needs a max voltage of 17VDC.

As for what SOLAR battery charge controller there are a few different ones depending one what you plan on accomplishing.

- If you do not plan on adding any more SOLAR than I would just go with the basic Sunforce-7-Amp-Solar-Charge-Controller model for around $18. It protects against overcharging.

- If there is a chance that you may decide to add additional SOLAR in the future you may want to invest in a Renogy 30 amp PWM model.

When you get the SOLAR panel, see what the Max voltage is.

I added a couple pictures below

Don

[AKGperson]

Hi Don,

Thanks for the information and diagram. I have a disconnect switch that I turn off when in storage so I will leave it off when charging.

Based on your question about the max output voltage of the Coleman 30 watt panel, I e-mailed Sunforce this morning and here is their response.

Hi Ken,
Thank you for your email.
Our panels are specifically designed to charge 12V batteries, hence their operating voltage oscillates between 15V and 17V DC. This means you will need also a regulator / charge controller with the panel. It will most definitely keep your batteries topped off.

Regards,
Fernando Pinzon
Technical Support and Customer Care
Sunforce Products
"The leading choice for Green Energy Solutions for more than 10 years"
Tel.: 514-989-2100
Fax: 514-989-2114

I don't want to take the battery lid off each time so I am thinking of installing this adapter Amazon.com: Battery Tender 081-0069-6 Ring Terminal Harness with Black Fused 2-Pin Quick Disconnect Plug: Automotive

and this extension cord Amazon.com: Battery Tender 081-0148-25 25' Quick Disconnect Extension Cable: Automotive because the panel will be free-standing next to the TT.

What do you think?

Ken

[bankr63]

I have a Coleman 40W crystalline panel that came with a Coleman regulator. The regulator is sold separately though. I attached it to the side of the battery box with some short zip screws. The wire into the battery box is similar to the one linked above; about 10" long and is permanently attached to the battery with a qc at the regulator. The panel is freestanding with an extension cord back to the regulator. I can leave it on the TT roof when in the storage yard (tied off so it won't catch the wind), and move it around the CG to catch the sun when camping.

[Mustang65]

Originally Posted by AKGperson

I don't want to take the battery lid off each time so I am thinking of installing this adapter Amazon.com: Battery Tender 081-0069-6 Ring Terminal Harness with Black Fused 2-Pin Quick Disconnect Plug: Automotive

and this extension cord Amazon.com: Battery Tender 081-0148-25 25' Quick Disconnect Extension Cable: Automotive because the panel will be free-standing next to the TT.

What do you think?

Ken,
Looks like it should work, but not sure as to how much voltage drop you will have with all that thin wire. Keep the controller close to the battery and let any voltage drop be on the higher voltage side of the system, between the SOLAR panel and the controller.

Don

[AKGperson]

Thanks, Don.

The panel comes with the wires so I plan to mount the panel on a piece of plywood that is slightly wider than the panel. I will then connect the controller directly to the panel wires and enclose it in a weather proof box to the side of the panel.

Based on your input, I will cut the extension cable to the shortest length possible to reduce loss but still be able to position it for the best sun exposure while in storage.

Ken

[AKGperson]

Thanks, Bankr63.

I won't be taking the panel camping because I plan to set it up for trickle charging with the batteries disconnected from the TT via the disconnect switch. The disconnect switch will be off while camping so that makes it more complicated. I want to apply the KISS rule for this one.

Ken

[Mustang65]

Ken,
Can you take the weather proof box (with SOLAR charge controller inside) and mount it on the back side of the battery box and just plug the SOLAR panel into it? One less thing to move around.

Don