OYMSAE 30 Watt 12 Volt Solar Panel Solar Trickle Charger 30W 12V Portable Solar Battery Charger & maintainer with Cigarette Lighter Plug & Alligator Clip

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.

For years, my Toyota Sienna van has been the ugly step-child of our automotive family. We're retired, so it sits outside and waits for the rare occasion when we both need a car at the same time or we need to transport something large and/or dirty that we don't want to put in our "nice" car. This means that sometimes it's a couple months before it gets on the road to charge up the battery. Due to this, we've gone through three brand new batteries in the past 7 years.I had a trickle charger on there before, but it was only 7 watts and really not up to the challenge. After spending yet another $200 on a new battery recently, I decided to upgrade to this 30W charger. It's only been a week, but so far, it's doing well.My wife wasn't thrilled about this massive solar charger blocking so much of the windshield, so I came up with a rather ingenious solution (if I do say so myself). We never use the moon roof, so I put it up there. It's working great.BTW... if you're having battery problems, it might behoove you to buy a battery monitor. I bought one on Amazon that has bluetooth. The bluetooth range isn't anywhere near what they advertise, but if I can get within 10' of the car, it downloads a minute-by-minute data dump of what the battery has been doing for the past 30 days, making it easy to catch battery issues before it's too late.

Update: seller shipped a replacement panel and this one is able to achieve 22-25watts. Seems like the previous one was out of box faulty. Giving 3.5 stars.On a bright sunny day with high irradiance and panel facing direct sun, it was able to produce 16 Watts. I tested its capacity with a calibrated meter and even 16 watts output was occasionally achieved. Keeping losses factor in mind, I think the 30watts model is no more than 18- 20 watts.

The battery pack in the back won't allow you to make it stick to a surface. It's to bulky. I have it connected to my camper battery as a trickle charger and seems to hold the charge.

I have only just received this item recently and have put on my pickup that I only use every once in awhile. I have a cigarette port that stays hot after key is turned off. I placed the unit (30 watt) on the dash and plug it in and the lights came on as indicated per the instructions. Since the unit was just received to keep the pickup battery maintained and charged up, I have yet to experience the outcome but I have high hopes that it will do as intended. I may update my rating review at a later date after given an allotted time to monitor the charging and maintenance performed by this item…