Sunforce 52022 5 Watt Solar Trickle Charger - Pack of 2

• Trickle charges and maintains 12 Volt batteries
• Made of durable ABS plastic and amorphous solar cells; Built-in blocking diode protects battery discharge at night
• Weatherproof amorphous panel charges in all daylight conditions-even on cloudy days!
• Works with automobile, tractor, SUV, boat batteries and more!
• Each panel includes 4 pre-cut holes for easy installation, as well as battery clamps, a CLA adapter, and 10 feet of wire

I purchased these solar trickle chargers all winter. I park my trailer at the storage facility for the winter. My batteries always drain down to nothing. I got these so try and see if I could keep my batteries from draining down to nothing. I built a small little angled mount for them using wood so I could remove it when I was not using them. I put the unit on the roof and made sure my batteries were fully changed first. I left the solar panels on the top of the trailer. I checked the trailer twice a month I checked the trailer and the batteies stayed charged up all winter. Good little units. Will not charge your battey it will maintain a charge.

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These things rock! I bought a pack and connected them to my ATVs and now they are always ready to go! One thing to take note of, though, is be careful not to switch the polarity if you use an extension cable!! I can say that from experience... Batteries aren't cheap either.

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They work great, but it would be good if an LED indicator was on these so one can verify there is traveling current, or not.

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Since I have several ancillary devices connected to the car's (2007 Ford Taurus) electrical system, there is always a trickle load on the battery. There is a ham radio that uses backup power when off, a GPS that trickle charges even when fully charged, and a GPS receiver that runs 100% of the time. The load is not a lot, but I wouldn't leave this stuff connected for a week without driving the car. These devices do load the battery enough that on long cold winter nights, the battery starts drooping significantly. For this reason, I looked at the charger panel(s), and after reading the reviews decided they would work perfectly in minimizing the impact of all these extra devices sitting in standby all afternoon and overnight. The combination of using the panel all day while inside at work, and from 4 p.m. throughout the night has worked out very well.

I'm only using one panel, the other is for a gift.

A few notes to clear up some confusion that I noted while reading the reviews:

1. The maximum output of 350 ma at 14 volts (loaded) is NOT enough to damage any lead acid battery (car/motorcycle/lawn tractor). Yes, unloaded the panel will put out 22 volts. That means absolutely nothing. As long as it sees a 12 v battery as a load, its output will drop into the 14 plus range, which is EXACTLY what a 12v battery should be seeing from a charging circuit, so no regulator is required (or even desirable) when charging auto/motorcycle batteries.

2. The panel will not discharge a connected battery, period. There is a blocking diode in the panel's wiring that prevents current flowing from the battery to the panel. If your panel is discharging your battery, then the blocking diode has failed (it is shorted). One possible, and I'm afraid all too common reason for this failure is having the panel connected when you start your car. VERY BAD IDEA. The instructions clearly state that one should not have the panel connected while the car is running. If the panel is connected when the vehicle is starting, very large voltage spikes are present on the 12v line and the blocking diode in the panel sees these spikes and may not be rated to stand up to them. The result: the diode shorts, and this allows the battery to send current to the panel overnight....all night.

3. As far as charging smaller (lower capacity) 12v batteries or battery packs, some caution needs to be observed. Nickel Cadmium (NICAD) or Nickle Metal Hydride (NIMH) batteries can be safely charged on a continuous basis at a rate of 0.10 X AMP HOUR RATING of the battery. For example: a 12 volt battery pack made of 2500 maH rated batteries can be charged continually at 250 maH. An 1800 maH rated pack of cells can only be safely charged continually at 180 maH. Since these panels put out 350 ma, neither of these batteries can be safely charged on a continual basis. This is where the charge controllers come in to play.

CONSTRUCTION:

The panels are quite well constructed and arrived properly packed. The supplied wire length with cig plug pigtail was long enough to go from the back window to the front accessory plug. Since the panels were provided with 4 screws for mounting, I bought some 1/4 inch plywood (cut to 1/2 inch larger around than the panel by our local lumber yard), and screwed the panel onto the plywood with rubber grommets as spacers/shock absorbers. I also bought some "gripper" feet at the local Wally World (hardware section furniture slider area), and put them on the plywood bottom to help prevent it from sliding around. The panels are clearly labeled "this side down", so it is impossible to mount them the wrong way!

PERFORMANCE:

Since putting the panel on, the rate of decay of the battery in the face of the loading of my devices, has decreased markedly. I have a digital voltmeter on the system and can see that in the morning the battery voltage is not as low as it had been prior to putting on the panel. It won't charge a dead battery, it won't make up for a significant current drain on your car battery. It will prevent a dramatic sag in battery voltage as a result of your car's microprocessor and alarm system running all night, as well as take care of a few auxiliary devices in the battery backup mode (maintaining memory of channels, for example). If your vehicle needs to sit long periods of time without running, these panels are a perfect solution, as long as you have access to sunlight. I measured the panel output at 21 volts on a fully overcast, but bright skied day, sitting in the back window of my car.

CAVEAT:

I have one concern about these panels. On a 30 degree day in full sunlight the panel became surprisingly warm to the touch, considerably warmer than the dash I had it sitting on. I'm not sure how things are going to work or how I'm going to deal with how hot they may get in full sunlight on a 90 degree Iowa summer day. At this point, it appears I have a month or two to ponder this issue. It certainly makes no sense if you can't put a solar panel in your car, (because it might get damaaged by excessive heat), when it is sold as a car charger.

Summary:

For the price and my purpose, this panel appears to be an excellent solution. Properly used and mounted, and with certain precautions taken, I would recommend this panel to anyone needing a 12v TRICKLE charging solution, where a charge controller is not needed (lead acid car/motorcycle/lawn tractor batteries).

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These panels worked great. I had a small window and these fit perfectly within. Gives a good charge of 22.5v each. Maintaining a deep cycle battery this worked great.