POWOXI Solar Battery Charger Car, 3.3W 12V Solar Trickle Charger for Car Battery, Portable and Waterproof Solar Battery Maintainer, Amorphous Silicon Solar Panel car Battery Charger

I have two cars I intended to use this charger on. The first is an older Citroen Picasso where I installed it on the rear parcel shelf connected to a rear 'always on' cigar lighter socket. This seems to work OK and I have had no trouble. Have left the car for several days, come back and battery seems strong on starting.Now the 'But'. I connected to my daughters Mazda 2 at the one and only cigar lighter socket. I was surprised the charging / connected green light came on as I know some other devices do not work from that socket, but the lighter itself works for what it was intended. Anyway I left the car for several days in strong day time sunlight. Green light was on during these times. However when I came to start the car after two or three days the battery was completely drained!I was going to buy another of these chargers for her car, but not now of course. I have no real idea why one car would be fine and the other not. I thought the electronics would prevent the charger being a drain on the battery while there was no sunlight to charge the battery but seems not. I could test by having the charger attached direct to the battery terminal posts, but in all truthfulness I am not that interested just yet.

Does a great job

easy to use and works as it should

I tried both but I can only leave one review SO for the 3.3V I give it 2 stars based on my experience BUT I give the 7.5V 5 stars.UPDATED BELOW: We have a third car which we do not drive very much and after having to repeatedly jump the thing due to a dead battery, I decided to try this out. We got the 3.3V as it states it will keep a full car battery charged - it did not.Now, it did work somewhat as after a week of the car sitting there without having being driven it usually was totally dead. We had a mechanic check for drains on the battery and there were none and the alternator was charging fine so it was totally a case of the stay alive features of the car draining the batter (which was new).We used a charger to fully charge it then put this solar battery tender on using the 12V cigarette lighter adapter and let it sit for a week unused. Normally, it would be totally dead but with the 3.3V tender in place for a week, the battery still had some charge, just not enough to turn the car over - so, could have something to do with our location (Edmonton, Alberta) or not getting enough consistent sun (it was cloudy for 3 days but sunny for the other 4) but, for us, it did not work. So, we returned this and will try the 7.5V version - hopefully that works better for out location. I will review that one once we receive it and I test it out.UPDATE: I will also write a separate review for the 7.5 V version but that one seems better suited to more northern locations and those that may get a decent amount of cloudy weather. I returned this version and tried the 7.5V and that worked way better in Edmonton, Alberta. The test took place in June so not quite summer but the weather here too was cloudy and rainy for 3 of the 7 days. Starting from a full charge, I plugged the 7.5V version in and a week later started the car and it turned over no problem. Without any solar charger, the battery would have been too weak to even turn over the engine; with the 3.3V the battery had more charge, but not enough to turn it over; with the 7.5V, it turned it over no problem. I am very happy with the 7.5V and the 3.3V might work better for those in areas to the south where the sun is stronger. However, for Canadians, especially those north of the 50th parallel, I highly recommend getting the 7.5V. So, for me the rating is 2 star for the 3.3V and 5 star for the 7.5V.

Easy to use and apply. I used them to charge my wave runner batteries. This charger keeps the the battery at an optimal level when the unit sits for up to two weeks or longer without use. Now I don't worry that they won't start. I store my skis on my dock with no power for standard chargers.