Bought this for a car that I keep at a vacation home and works perfect! The vehicle is only driven a few weekends out of the year so the battery would always be run down when I arrived. The car sits in a parking garage that is open on the sides and even that small amount of sunlight is enough to keep it charged. Amazing. Love it. I've had it for about 6 months now and both times I've been there since Ive installed it it has started perfectly. I do recommend hooking it up to the battery and not the cigarette lighter because I guess in my car when the car is off so is the lighter.
This is a great little maintenance charger and will help keep a less frequently used battery topped off and ready. I am on my second one, and obviously liked the first one enough to replace it with another. My first one died after an unceremonious fall to the concrete floor but it worked great up until that point.
The main downside to this charger is the non-standard wiring with regards to the SAE plugs. It's an accepted standard with SAE that the positive line coming off the battery have the shielded terminal. This is done to eliminate the risk of a short circuit if the terminal ends touch the vehicle chassis. Eliminating a possible short circuit is a priority on the battery side, where risk of fire and/or explosion is inherently greater than on the charger side. The charger and accompanying accessories are wired in opposition to this standard. In truth, if you only use this charging device, and take care when using the alligator clips, it would probably never be an issue. If you have any other real charging devices that use SAE plugs, you will need to pay special attention to what you are plugging into what. I, personally, just rewire the charger and both of the included attachment devices, thereby eliminating the possibility of an accident based on incompatible wiring.
Noticed people weren't telling about the most important feature: Has a built-in diode for overcharge protection when the battery is charged fully and discharge protection to prevent discharge of battery when there's no light for charging. The discharge of batteries is a big problem that cheap solar chargers have. The blue flashing light indicates when there's enough light, even on cloudy days. On a vehicle I don't drive too often, I connect the battery directly with the enclosed battery clips since the cigarette lighter shuts off when the key is not in the ignition. I thread the wire (7 1/2 feet long)through the opening by the windshield wipers and close the hood then it thread it to inside the passenger compartment and gently close the door on the wire where the door's rubber gasket prevents the wire from being damaged. The solar charger is laid on the dashboard. If you want to leave it outside, there are instructions to make it waterproof by putting sealant on the vulnerable areas. The instructions say not to use it when the vehicle is moving but doesn't say why so I believe it may be for a safety factor of the charger placed on the dashboard area more than anything else. The maximum operating temperature range of -40 to 176 degrees F. makes it idea for outdoors.
The construction seems solid enough, but be warned it's not intended to be mounted outside in the weather. Mount it on your dashboard under the windshield.
The current produced is extremely small. You WILL NOT charge a battery in a day or 2 with this panel. It says "Maintainer", and that's what it is. It will only provide enough power to keep a battery from going bad. Just for fun, I hooked it up to a small electric motor and 4 wheels, and at high noon with no cloud cover it couldn't even move itself.
I have an old vehicle I use for junk runs and backup when regular car is in for repair. After sitting for two months I need to recharge the battery. This should keep it charged. I will know the next time I use the vehicle.
The Sunforce50012 1.8 WattSolarBatteryMaintainer gives you another reason to love the sun -- it'll help keep your car's battery charged. Just plug this helpful 1.8-watt solar charger into your vehicle's 12-volt lighter socket and position the panel to pick up the most daylight possible. Or, if you prefer, use the included alligator clips to connect it directly to the battery, so you can keep your lighter socket open for cell phone chargers or other accessories. Regardless of how you hook up the battery maintainer, you'll never get caught off guard without the juice you need to start your car. This device is designed to work with automobile, all terrain vehicle (ATV), personal water craft (PWC), and boat batteries, and is even effective on cloudy days. The 50012 is made of durable ABS plastic and amorphous solar cells, measures 6.5 x 1.25 x 18 inches (WxHxD), and has a maximum temperature range of -40 to 176-degrees Fahrenheit.