Adding a solar charger for the breakaway box

[nikdfish]

I ordered some components for adding a solar charging system to our Aluma car hauler's breakaway kit battery. The trailer often sits a long time between uses. I should get the solar panel in next week. It is a 12"x6" aluminum cased 5 watt panel. No blocking diodes, but I have some suitable ones on hand I can add in. I also have a small, waterproof, 3 amp controller on order that should show in a week or two. It may be over kill for the short term, but better for the battery in the long run with more daylight.

I'll post some pics as things come in and get installed. I am hoping the controller will fit inside the battery box along side the battery and I plan to use anderson power poles for connecting the pieces to make servicing easier.

Nick

 

[k0ua]

I ordered some components for adding a solar charging system to our Aluma car hauler's breakaway kit battery. The trailer often sits a long time between uses. I should get the solar panel in next week. It is a 12"x6" aluminum cased 5 watt panel. No blocking diodes, but I have some suitable ones on hand I can add in. I also have a small, waterproof, 3 amp controller on order that should show in a week or two. It may be over kill for the short term, but better for the battery in the long run with more daylight.

I'll post some pics as things come in and get installed. I am hoping the controller will fit inside the battery box along side the battery and I plan to use anderson power poles for connecting the pieces to make servicing easier.

Nick

I have my little 20 watt solar project up and running now. I use the little battery tender solar controller. It would be suitable for you application. Simple sealed up and small and rugged. Simple screw terminals on each end for connections. I am using anderson powerpoles also for all of the inside connections, and of course the MC4 connectors for connecting up the panel outside.

Amazon.com: Battery Tender 21-1162 Solar Panel Charger Controller: Automotive

 

[Snowback]

I think you will be pleased with your described setup Nick. I went with a 10W unit as described at this post: http://www.tractorbynet.com/forums/...ery-maintainer-good-bad-ugly.html#post4643097

If the controller ever fails I'll pick up the one James linked above and splice it in. So far so good with this one though.

Good luck!

 

[ModMech]

Even a 2W panel is enough, you only need to maintain, going with a small (less than 5% of batteries rated current) means no charge controller is needed because the internal resistance of the battery effectively prevents overcharging!

 

[HarryVanderpool]

I hate to be Debbie Downer, but 5 watts is overkill for a battery that is never used.
You are going to have to keep an eye on the electrolyte levels, especially in summer.
We have a vertical lift gate at the end of our drive that opens and closes several times daily.
It has a 198ah battery that is charged with a 5 watt panel.

If you are going to use the 5 watt panel, I would cover it with a matt and uncover it for a couple of days each month, or install a disconnect.
5 watts isn't much, but it's alot going into a battery that is not used.

 

[k0ua]

I hate to be Debbie Downer, but 5 watts is overkill for a battery that is never used.
You are going to have to keep an eye on the electrolyte levels, especially in summer.
We have a vertical lift gate at the end of our drive that opens and closes several times daily.
It has a 198ah battery that is charged with a 5 watt panel.

If you are going to use the 5 watt panel, I would cover it with a matt and uncover it for a couple of days each month, or install a disconnect.
5 watts isn't much, but it's alot going into a battery that is not used.

But if he uses a charge controller it it will never overcharge the battery.

 

[ModMech]

Depends on battery capacity (A-Hr rating), if the panel amperage (5W ~ 0.4A) PEAK is below 5% of the battery capacity, then it is perfectly safe.

This is used all the time in renewable stand-by systems where you really only need to maintain and not charge with a solar panel.

 

[nikdfish]

The current trailer location is sub-optimal for a solar application, so I won't know true output until installation (and location may change over time). I figured a controller is cheap insurance. If memory serves from the last replacement, it was a 5 AH battery.

Nick

 

[ModMech]

Yup, a 5 watt solar panel is just above the 5% "safe" range, but not WAY above. Considering that all panels are rated "peak", meaning oriented to face the sun on a clear day and given that no panel used for battery maintenance will ever achieve anything close to that rating, you would be OK w/o a controller.

It takes an expen$ive controller to improve a panel's average input to the system and only totally off-grid home/business power systems would benefit from this type of controller.

 

[nikdfish]

The UPS guy brought the panel today, so I got some things done. The panel had a bypass diode, but did not have a blocking diode so I added one to the + lead. (I thought it kind of funny which diode use was chosen by the manufacturer, as a bypass diode is only needed in a multi-panel setting & a blocking diode makes sense for most any battery application which might not have a controller ). I terminated the factory leads with a pair of anderson power pole connectors with the usual orientation (red right & tongues up - an ARES/RACES standard for radio guys...).

Install was pretty simple, a couple of tabs cut from some aluminum angle & a few self tapping screws was all that was needed.

Rather than disturb the existing wiring, I made some spade connector "go betweens" to mount between battery & wiring harness. Two leads came off these connections & were terminated with anderson power poles. You can see the junction of power pole connectors between panel & battery nestled between the battery box & breakaway pull switch.

I checked the battery voltage after getting things installed (checked at the power pole connectors) and it looked pretty much fully charged, even though the last use was probably 3 months back.

The cheap, water proof, 3A controller should show in a week or two (China post...). When it does, it will get wired in "down stream" from the solar panel connectors so the panel can be easily disconnected if the battery needs replacement as you don't want a solar panel connected to a controller without a battery being connected.

It is most probably overkill for now, as the current setting does not make full output of the cell very likely.

(sky view)

(view to the south)

Nick