Solar battery tender

[Flyrotor]

I have recently moved to San Antonio and now have to store my trailer, previously in Idaho I was able to keep my trailer at home.

I hate the fact that the batteries are not being charged like they used to be, so today I bought this solar panel from Northern Tool.

It is only rated at 7 watts, but sitting in full sun for most the day should keep it topped off. With the solar panel connected to the batteries, I was immediately getting a full charge indicator on the basic panel indicators (batt, grey, black, fresh).

It was pretty simple to hook up, it comes with a cigarette plug and alligator clips, I cut the wires off the plug and connected them directly to the battery, I mounted the solar panel onto a piece of plywood, painted it and attached it to the top of the propane tank cover. It will be secure for travel and will remain in place all the time, providing a passive battery tender. While in storage the trailer is disconnected from the batteries so there will not be any parasitic drainage from on-board equipment.

It is not intended to provide power while camping, even though I will keep it attached at all times. I will continue to use either hookups, or my generator to maintain battery charging while camping.

I will follow up when I get a chance to see how it is working while in storage.

[RoyBraddy]

Both my OFF ROAD TRUCK and JEEP Wrangler back in the day always had one sitting on the dash for keeping the start battery topped off... These were neat back then as they just plugged into the 12V lighter socket. Today it is very hard to find a 12VDC lighter socket that stays 'ON' after the ignition key is turned off.

I really should get back to this keeping my Truck start batteries and trailer batteries topped off...

Just keep in mind this only really works to top off your battery that is already charged up...

If your battery has been drained to 50% or lower than battery science tells you if you want to get it recharged in a quick three hour time frame than you need to charge it with 14.4VDC with a current capacity of at least 17A to 20A per battery in your bank.

Obviously the 7-10WATT small solar panels is NOT going to provide any of this...

Photos from GOOGLE IMAGES

One thing you should watch for is to make sure the SOLAR PANEL has the BLOCKING DIODE installed to prevent any loading to your batteries when the SUN is not out. This will prevent the SOLAR panel from discharging your battery.

You can easily use velcro to hold these panels in place on your truck dash.

Roy Ken

[Seann45]

I would put it inside a South facing window of the RV and plug it into a power point access otherwise it WILL disappear on you..

[Mustang65]

i checked the online user manual and the unit has a blocking diode.
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From user manual:

NOTE:
This solar panel has a built in blocking diode to prevent reverse discharge.
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Don

[Flyrotor]

Roy, I installed it with only intentions of a battery tender.

Sean, I keep the trailer in an RV storage yard, all my windows are tinted, and the trailers are parked too close to be efficient via the windows. Yeah, there is a chance it can get stolen, but so can my batteries and propane tanks, just a chance I have to take, or remove all when in storage.

And yes, it has a blocking diode, I checked that feature before I bought it.

[NC Roamer]

I use one of these to keep a charge on the starting battery on my 8KW generator at the house. It works very well.

[clubhouse]

We used one on our sailboat for years to keep the AGMs topped off. It was perfect since our slip didn't have shore power, and running the motor just for the alternator to charge batteries was very undesirable on a sailboat.