20 Watt 12V Flexible Solar Battery Charger & Maintainer – 20W Ultra Lightweight ETFE Solar Panel with Built-in Intelligent MPPT Charge Controller +…

 I bought the BC-20W ETFE Solar Battery Charger to be used on my boat which is stored at a facility where there is no electricity available. Having to tow the boat home only to charge it and then return it before the HoA complained was a lot of hassle so I decided to try solar. The 20 Watt panel is sufficient for battery maintenance as I quickly learned with a backyard test using a 35Ah battery in a Minn Kota battery box with test light. I depleted the battery to approximately 70% level before connecting to the charger.
Even on a rainy day with thick overhead cloud cover, the unit delivered pulse charging to the battery. By the following day, the battery was fully charged.

The build quality is very good and thicker than you might expect so not to blow off the boat in a wind gust. There is also sufficient flexibility if you wanted to mount the unit on a curved Airstream roof. The kit comes with all you need to connect to the circuit whether it be by battery terminal loops, alligator clips or just a standard SAE connector.

I took a short video to illustrate the unit working even in the rain. My multimeter illustrates a pulsing charge of 0.37 amps at a voltage of 13.1V. That’s only 5 Watts, but this reading was taken once the battery was full and the MPPT controller was in pulsing (or maintenance) mode. I did not have a sufficiently dead battery available to check the power delivery during a continuous charging cycle but I’m fairly certain it would deliver the manufacturer’s stated 20W output.

I had previously purchased a 20 Watt traditional type solar cell battery maintainer solar cell from Suner Power and liked it so much I decided to buy this one when it became available to keep my RV coach batteries charged. It arrived in sturdy cardboard packaging with a foam shipping insert to hold it secure and cushion against damage. While it has flexibility, you cannot bend it in half like a taco without damage and the manufacture’s instructions state no more than 30 degrees of bend but I would recommend no more than necessary. I also like it that it is “Plug and Play” and you don’t need a voltage regulator as it has that as well as a overcharge protector built into it already. The solar cells are not smooth like the traditional cells I have owned before but have a textured, bubble like feel. This textured surface, according to Suner Power, causes the light to bounce and ricochet after hitting the surface and thereby enabling the cells to capture more light and convert it to photovoltaic energy. It should also allow for better performance in lower light conditions, I would think, and this science behind the design is one of the things that attracted me to purchase this device. I hooked it up and, using the instructions (they are a little difficult to understand) but, after my previous experience with the 1st solar device I bought from Suner Power and having their customer service folks talk me through how to check for proper operation, I was able to get my multimeter hooked up properly and found the output voltage from it to be OK. I watched it for a couple of days and my batteries were putting out 12V when I left home to return to work on a drilling rig in South Texas. When I return home in a few weeks I will be checking it again and hope to give an updated review. For Now, I am well pleased with the purchase.