3.5W

I held off on even trying this on a battery, because of the high voltage people commented on. I finally hooked it up to a disconnected battery in a car that wasn't in use. Voltage without charger was 12.40, with charger it was 12.40. Reconnected battery and charger, and it still measured 12.4 volts next day (my Outback draws about half an amp). Only problem is the suction cups won't hold worth a @#$% for any significant time, and I have the black and blue toe to prove it!One caveat: I would make sure to disconnect solar charger before disconnecting car battery. Otherwise you may fry the car's electronics.

Left it for a month on my car and my battery was at 100%. Works as adverized.

Wattage was not as described

In my area it's not the rage to hook these up to your batteries on your boat so that you can keep it fully charged until you're going to use it next. Hook up was extremely simple as you can think to alligator clips run it up laid on top somewhere either on your cover or any other flat spot. I decided not to use the suction cups because it really had no value for me. As for it working? I really couldn't tell you I can tell you that my battery was never dead and always seem to be fully charged I've left it on there now for a number of years and I just don't seem to have any issues in it Pierce to be working just fine during the winter months it's definitely nice to have it on the battery to keep it fully charged what I purchased them again? Yes.

With the panel on the roof for direct Sun, we keep it plugged into a cab outlet that interfaces directly to the battery all the time (vehicle on and off).

Put this on my battery over the winter to keep my battery ready to use for the summer

Bought this to keep the battery on a Ford Explorer charged over the winter. Maybe we were asking too much of it, but we had done this with other brand solar chargers in other cars before. In any case, when we arrived in the spring after having this in the window and connected to the cigarette lighter, the battery was dead. (We tested that the cigarette lighter was powered even with the ignition off before plugging this in, to be sure it was not ignition switched power connection.) I'm not sure why it didn't work, but will have to buy a different one as I don't trust it for a second try since it failed once. (We charged the battery in the spring with an ac charger and then it worked fine after that, but with this solar trickle charger it didn't have enough power left to start the car. Car normally sat for 1 week before drives when we were using it, so it doesn't have a super-super high drain rate, but maybe the clock/etc. drains it in the winter faster than this could charge during overcast periods.)

Used for maintaining battery charge on tractor and trucks, good value!

I had a charger just like this one that was given to me years ago and it always kept my car battery topped up OK but sadly the wire snapped off right where it goes in the solar cell so looking for a replacement on Amazon I saw this solar charger and it looked exactly the same as my old one so I bought it and I do belive my old one was the same make so very happy with my purchase thank you

its nicely made.it has an LED light that gives feedback that it is operating. it has a long lead and alligator clips.

Left my motorhome in storage during the winter and the alarm drained the battery. This handy device means I never have to have that pain again.

I urs it to keep my boat battery fully charged

I purchased two of the solar chargers. On of them worked. The other didn't and had to be returned for a refund.