Sunway SolarPanel Car Battery Trickle Charger & Maintainer 5W 12V Solar Power Charger kit Portable Waterproof for Automotive RV Marine Boat Truck Motorcycle Trailer Tractor Powersports Snowmobiles

Seems to work awesome to keep my atv battery maintained that's stored in my enclosed trailer made my own mount on side of trailer see photos below the suction cups are worthless just throw them away my opinion. Has a convenient plug in for testing charge with a green light.

so far these haven't disappointed me..i said "these" because i like them a lot that i bought 2 more..so i have 3 sitting in my car feeding my batteries on it..

[update 9/2020]Okay so you got that part about the polarity is crossed between this unit, and a unit like Battery Tender?I'm not getting into who is 'right' or 'wrong' on these things, but the cross over plug is cheap (and the seller even offered to send one, so check with them) ... and they need to resolve that.... however...I need to upgrade my rating - because once you get past making it work, it seems to work quite well...!I've had this plugged in (once I got the crossover) to my Battery Tender pigtail that's connected to the battery of my motorcycle. Without this, I would plug the Battery Tender in when it was getting hard to start... and then I'd forget... and then I'd be buying a new battery. I can't really string a power cord to the carport all the time... So, this might have happened to me, err... more than once? (There's a reason I was looking for this product, right?)This has really worked to solve that problem... the solar panel sits near the bike... and it's not really in direct sunlight all that much... but even with all the crazy distractions of the pandemic (me not riding for months), the bike is now happy to start every time!(Of course this DIDN'T stop the problem of me needing to get out and ride, but at least the battery isn't dead, right?)So I'd still be delighted if they'd work out this need for a crossover plug (if you have the "conventional" Battery Tender), but it sure worked well in my situation. (Much better than the BT solar model I tried to get working - that got recycled. wasted my money).Best of all, I gave in and ordered a second unit for another bike - I think it's worked so nice, maybe I can stop buying new batteries for that bike, too?So I'm obviously sold... and the vendor offered great support (even if I didn't take them up on it) and I'm quite happy with the product! (Well, except for the polarity, but now that I'm forewarned, I can deal with that...)Buy it, sort out the plugs and polarity, and once it starts working it's great.-----------It looks like a great product... put it in the sun and the dongle with the LED lit up...But after reading their notes, and then looking at the cable, I can see why they caution not to connect to existing cables!After using Battery Tender (and a few clones) I have a pigtail already hanging off my battery - but the polarity of this "charger" is backwards!I can just see the design argument... (Yeah, well the battery is the source.... no the charger is the source... no, the... <PTZZZ> ... crud, we need a new charger, and maybe a new battery!)Really, I don't friggin' care, but if I plug this into the existing pigtail I'm going to make a mess and nothings going to get charged.So, cool product, but they cabled it like it's the source (battery) and not like it's charging the battery... so if you're not going to use the supplied (nearly useless) connectors, then get your voltmeter out before you plug it anywhere.

I would recommend this

I purchase this to keep our forklift battery charged when not in use. Does a great job.

Edit* below is what I thought before it broke.Went from 5 stars to 1 not sure how warranty is yet but I’m looking into itI’ve only had it a few months so idk how long it’ll last.It’s been a game changer for me though!I have it gator clipped onto my skiff battery, that keeps it charged to run my bilge pump on a float switch, in SE Alaska where it rains pretty much every day and not much light either. It’s been on top of my canvas T-top that has been covered in snow, salt water spray, and getting rocked and slammed pretty hard in some nasty weather. My pump switch got left on (froze) a few times that drained my battery, and my battery was submerged in salt water before I installed this and it’s been holding a charge since! Couldn’t be happier with it.

Was skeptical at first but I installed it on my she'd to keep my mower charged. Solid construction, even came with a test mudule. It works...very well.

After 2 years, the plastic begins to warp and deform.