30W 12V Solar Trickle Charger Maintainer, Waterproof Portable Solar Panel Battery Charger Kit with Cigarette Lighter Plug & Alligator Clips for Car, RV, Truck, Boat, Motorcycle, Marine

Here are my observations. First off I park facing a 2015 Ram Dually with the 6.7L Cummins facing due east - this gives me the front and side windows to mount two in during rhe winter months, and the side window alone to mount one in dyring the summer. The solar cell mat sits well in the passenger window by itself. And I lay the other in the front dash. These also stay hooked in full time - never being disconnected (stow them on the floor between the passenger seat and the door at the belt base to keep them upright). Truck has an Aftermarket Car Alarm that tends to work the batteries moreso than a normal truck. Truck stays sitting for a week at a time (during summers up to a month, and maybe once or twice like this during the winter) in Buffalo, NY. Batteries are 2-each set of $350 Odyssey H7 Batteries, Absorbed Glass Mat (AGM) P/N ODP-AGM94RH7. First off, I run one solar charger in the summer and two in the winter. What I found was that during the winter, a single one was OK, but due to the amount of snow buildup (and just the lower amount of sun), that I needed two running together to top off the battery. And, that and the fact that they tend to go bad in the winter and I couldn't risk loosing charge on a 4 week run and flatten $700's worth of batteries. Also, Batteries always tend to go bad in single digit weather in January and February. Observations: Brand new I could get the charge to 12.4V during the summer during the first year. The winter's, it's more like 11.8-12.2V; but it honestly couldn't seem to keep up, finding it after two weeks straight at 11.4V at times with just the single charger. On year two I noticed the batteries couldn't seem to go north of 12.2V in the summer. In November, I bought a replacement solar charger as the first one finally went; but then I also bought a second one due to the likelihood that while sitting for several weeks straight, that this one charger failing could take out both of these batteries. So now with two Solar Chargers installed, with a dual-headed 12V splitter (Power Drive PD9223BL 2-way 12V Adapter), I was able to get to 12.2V, and even 11.8V with the windows covered (the side window less than an inch, but the front burried) - honestly, the solar cells still charge somehow. So during rhe winter of 24-25 (and at this time of writing), this configuratuon has worked flawlessly!!

Amazing product, no longer running vehicle weekly to charge battery. Works as intended.

Original Review: At first I really liked the panel, I have a Bluetooth adapter that reads battery voltage and I could see the charge go up if I sat there for a few seconds. I was checking voltage regularly (every 2 or 3 days) to make sure it was keeping my battery at the properly charged, which it was. So when I finally decided to trust this and not be checking it so often, it stops working. Now I have a dead battery and will have to pay to have it replaced. Not happy. Updated Review: Let me start by saying that the reason my battery drained was not this solar panel's fault. Turns out the Hands-Free Link module in my car had gone bad and was draining the battery even when the car was off. Once that was found to be the issue, thanks to a friend that has the same car I do and coincidentally started having the same battery drain issue too, he told me what was causing and how to get to it to unplug it to test if my HFL module was draining the battery. After the HFL module was unplugged I then though to take this solar panel out from storage and check, I had not used it since I labeled it as "bad" but never got to throw it away since I thought it did put out some power just not enough for my car. Well now I can say that my car can sit indefinitely, the battery will not die anymore and has not gone bellow 12.3 volts even after 3 weeks of the car not being used.

Worked as expected.

bought the OYMSAE 30W 12V Solar Trickle Charger to keep the battery on my truck topped off, and I’m honestly impressed by how well it performs. It’s compact, lightweight, and super easy to set up right out of the box. Whether you use the cigarette lighter plug or the alligator clips, installation takes just a couple of minutes—and you’re ready to harness the sun. I’ve been using it for a few weeks now and it keeps my 12V battery healthy and fully charged without overcharging. Even on cloudy days, it still delivers a consistent trickle charge. The built-in smart controller with overcharge protection gives me peace of mind, and I love that it’s completely maintenance-free. It’s perfect for cars, trucks, boats, RVs—basically anything with a 12V battery you don’t use every single day. I keep mine on the dash and let it do its thing. No more dead batteries when I come back from a trip! If you’re looking for a durable, portable, and efficient solar battery maintainer, this is it. Totally worth it.

(Update) These panels warp after sitting in the sun. This causes the box containing the charge controller to not sit against the board any longer. Condensation and water come along and... you get a fancy panel that lights up the LEDS (in the worst place possible for this unit) but will not charge a battery. Keeps our battery charged even with some small constant drains, and even when it is a little overcast. Very impressed. Only issues are the quality of the wires and SAE connections. They could have sprung for the gold plated and with ones that fit better... these dont quite fit other proper SAE connectors without forcing them. So extending the cord is problematic. The instructions really should just be printed on the rear, so you know what the lights mean, and it would be nicer if I could see the status without having to look under the panel. Also, the status lights do not light up if there is no sun, so this cant tell you level of charge, or even tell you if the battery is full without sun.

My husband bought the solar charger quite a while ago, but I did not want to do a review until we've used it quite a lot. I must say this wireless portable power bank is amazing. I took my grandchildren to the amusement park and all 4 of us used it during the day to keep our phones charged and it still had plenty of charge left when our phones were full. It truly does have a long battery life. I love the versatility of the chords, where I have an android phone and my grandchildren have iphones. All our phones can be charged from the same charging unit. Only later was I told it was a solar charger and a flashlight which makes it even more useful. It is a bit heavier than our other 10,000 mAh chargers. However, it is also triple the mAh of the other ones at 30,000 mAh. I'm quite happy with the product and definitely give it a five star.

These little units are handy I know it's not the intended use but I wound up putting this on my ford 4800 when the alternator went out a year ago. Still haven't replaced the alternator.(Truth be told I only run my tractor for about 6 weeks out of the year)