10W Solar Battery Charger 12 Volt with Upgrade Charging Algorithm, 2023 Upgraded Solar Car Battery Charger for Boat Car RV Motorcycle Marine Automotive Black

The advertised dimensions of the panel were said to be 11.02"D x 12.6"W x 0.79"H.That would be roughly 138.6 square inches.The panel they sent me has a sticker on the box claiming 10W output, but the panel measures only 7" x 14"; which is roughly 98 square inches.138.6 / 98 = 1.41410 watts / 1.414 = 7.07That is why you cannot get any more than 7 watts out of this panel; even in the blistering southern Alabama sun. I was hoping for the 10 watt panel that I actually ordered, because of windshield glass and cloudy weather losses.With clouds drifting across the sun, I saw only 20 to 40 milliamps of charge. But as the full power of the sun was exposed, this charger pushed 0.53 amperes at 12.85 volts into this mostly-charged 50Ah battery here. That is enough power to top up the charge within 25 minutes or so, on a sunny southern day. Let's say you make a short (5 minute) trip up to the store, then you start the car again to drive the 5 minutes back home. This charger should be able to do the job the alternator had insufficient time to do. Hopefully this [undersized panel] charger here will be enough to carry the load, behind the rear windshield glass. (as in .095 ampere photo in partial clouds)As the battery voltage approaches 13 volts, this charger begins to dramatically throttle itself down. By the time the battery floats up to 13.1 volts or so - the charger delivers barely any current at all, even in full sun, just as it should do (as in the final photo). If you then momentarily throw a small load on the battery (let's say 8 ohms [roughly 1.5 amps]) - the voltage will fall down below the threshold at 12.9 volts or so, and the charger kicks back into high gear for a bit. Then it eases back off and floats the battery @ 13.1 or so. It's a beautiful thing to watch.You might be able to get up to the 14.4 volt absorption voltage on a small motorcycle battery, but this charger is way too small to push a car battery that hard. Anyway, this float charge is much better than leaving the battery sitting there partially depleted for days on end; .707 times advertized screen size notwithstanding.I just wish I'd get refunded for the reduced panel size, and resultant unavoidable power loss. I paid for a panel 1.414 times larger than what they sent. $32.39 minus (.707 * $32.39) equals $9.49 refund. I'll report back and let you know if I receive it.

Using it to keep the battery to my portable water sprayer charged which is used daily for about an hour. Was having to remove and charge battery every other day. Haven't had to since installing this solar charger. Mounted it on the front rack of my ATV. The sprayer and battery are on the back rack, so it's always connected to the battery. Works in full to partial shade.

First, the product worked as described and is very easy to plug and play with multiple connectors. Panel is a basic flat solar panel with no mount other than 4 suction cups which are perfect for a car window but if you are using in another way you will need to mount with screws and large washers or purchase a solar panel mount.

EDIT: After changing out the fuse for the 12v plug it seemed to work pretty good plugged directly into the 12v outlets. This is good because now it makes it a lot easier to keep a charge on the battery without having to have it directly attached to the battery under the hood with the provided alligator clips. I changed to 4 stars to reflect this update.So I have had this a couple of days and have run some tests on it. I have a voltmeter in the car that can be turned on and off to show the current state of charge for the battery. Here's the problem with this product. I have multiple 12v sockets in the car. The factory one will only work when the key is on. The others are directly from the battery and fused and work independently from the key. When plugged into the factory 12v socket it will actually turn on some of the accessories like the clock but it does not increase the charge to the battery (no change in meter voltage). So I tried the non-factory 12v socket and it also does not charge. I know the panel works because when I hook up directly to the battery with the alligator clips it works pretty good actually. This will be a big inconvenience and most likely a deal-breaker and will have to send the product back, unfortunately.

We have a car that doesn't get used often and the battery kept going flat. We plugged this in to the accessory socket and put the panel on the dash and it works perfectly to keep the battery charged.If you're plugging into a socket, you need to make sure that the socket has power even when the key is off. Many modern cars don't work like that, so just be aware. If that doesn't work, there are battery leads with either alligator clamps or ring terminals that you can attach directly to the battery. The leads aren't terribly long though so depending on your application, you may need to make longer ones.It's been in use since January 2023 and has been perfect for what we needed.

I haven't had the chance to install it yet but of it works like it is supposed to it will be great.

LED lights are nice on the back.Good battery maintainer at 10W is the smallest I'd suggest for a car battery.

Charging lights came on when I hooked it up to a battery in the garage and that was using bright sun thru a window. Everything arrived intact and nothing was missing. Arrived on time. I’m going to use it to keep the battery charged on my winter plow tractor that I use to plow the driveway. Hopefully it’ll help avoid hard starts