Schumacher Electric Solar Battery Maintainer, SP-200, Quick-Connect Clamps, DC Accessory Plug, Water Resistant, 2.4 Watts, 12 Volt, for Car, Motorcycle, Lawn Tractor, ATV, and Marine Batteries

Kept my battery full for periods of non-use. I use this in the cigarette lighter since my car has an always-on plug there. But the package included clamps to use straight to a battery. The only thing I wish the panel had was a longer cord, but its long enough to reach the back shelf of a full size sedan. I have no complaints with this little guy!

Planning to leave the country for two years, I put my truck in storage in summer 2018, sitting outdoors in Texas, no sun shade. I had just bought a brand new battery for the truck and thought it would be a shame to let the $90 battery die while sitting there. After reading a lot of reviews of inexpensive solar battery tenders, I bought this, feeling no confidence it would work, much less even survive. I disconnected the battery from the vehicle, connected this tender, and left.When I came back, life happened, and I didn't get my truck back until late 2023, when I towed it to the driveway to sit until now, Feb. 2024.I just assumed the battery was dead after five years, tender or not, and was already removing the bracket to trade it in on a new one, but I thought, why not just test it? The multimeter said 12V, but I still didn't quite believe, so I connected the battery back up to the truck. I couldn't believe it actually cranked over, and very strong, too!However, the battery tender's plastic cover melted under the Texas sun. I don't think that's the tender's fault, though: you can see the cracks in the truck's dash that weren't there before.So it's liking like this turned out to be a good bet: $30 to save a $90 battery.

I bought this to keep the battery in a very infrequently used old truck topped off. It is parked outside so it gets plenty of sun through the windshield. I just put this on the dashboard and plugged it into the cigarette lighter and it works great. (I did check to be sure that the cigarette lighter worked even if the ignition was off, otherwise I would have had to connect the charger to the battery directly.) The directions do not say if it is necessary to disconnect the charger when starting the vehicle, but to minimize the chance of any damage to the charger, I do so.

This charger does not have a diode in it. Without a diode, when there is no light shinning on the panel, the battery will back feed and discharge the battery. You have two choices, install a diode in line on the positive lead with the banded end towards the plug end or disconnect the charger once there is no sun. The charger works as advertised and is great to keep up a fully charged battery. If you have a newer vehicle, they have a continuous battery discharge from things such as alarms, clocks and other things. This charger may or may not put out enough amperage to produce more charging power than is removed by the vehicle. On an older vehicle, there are far fewer things that draw current from the battery with the vehicle off, so the charger will work to keep your battery charged.This is not a battery charger, it a maintainer for a fully charged battery, as designed.If you have a newer vehicle, I'd get a 5 watt or 10 watt panel and a charge controller so the higher output from a larger panel will not overcharge the battery. This panel is also great if camping, ect. for the times you are using a battery to power a devise. It will help the battery keep up it's voltage longer.Overall, it's a great deal if you install a diode. The diode costs less than one dollar. Go to Radio Shack and let them know what the diode is for and they will get you the right part, otherwise, disconnect the panel at dusk.Also, don't position the panel so shadows fall on it. It's not as critical with this type of panel as it is with some others.

Does not work at all, even after leaving it to charge for several days

I recently purchased the Schumacher SP-200 2.4W Solar Battery Maintainer for my motorcycle and I am extremely satisfied with its performance. The device is water-resistant and can be left outside in any weather condition, which is a great feature.The solar panel is incredibly efficient and charges my battery quickly and effectively, even on cloudy days. It has helped me maintain my battery's life and saved me the trouble of having to jump-start my bike every time I want to use it.The SP-200 is very easy to set up and use. It comes with all the necessary cables and connectors, and the instructions are straightforward and easy to follow.

I got this to try to maintain the battery on one of my vehicles which is rarely used and usually stands parked for months at a time. It did work for this specific car - it provided enough power to compensate for parasitic loss from alarm system and other car systems, however it only works if your car is exposed to enough sunlight during the day, with a clear windshield (yes, it is also rated for "outdoor" use in "light rain" but the enclosure feels pretty flimsy so I wouldn't recommend to leave it constantly exposed outside of the car) . I eventually moved the car to different location, under the shade of the roof, so I had to get rid of this and instead got the regular "Battery Tender" which you just plug it into nearest AC outlet and connect straight to your car's battery terminals.So if you leave your car parked in a well-lit parking spot, without cover or any nearby AC outlets available - this item might be useful (just remember to occasionally check it with multimeter to see if it is still working and not defective). Otherwise you should get a regular "battery maintainer/tender" device instead - it will provide you with constant source of electrical current regardless of weather condition, these devices are more reliable, more durable and overall much more convenient.