Review on 🌞 ALLPOWERS 18V 12V 5W Portable Solar Panel Battery Charger for Car, Boat, Motorcycle, RV Batteries by Born Waheed

I bought two of these five years ago to keep the batteries in my wife's car and van charged. Unfortunately, they didn't work in any car. I took them off and put them in the shed. Early last winter I bought new batteries for our cars and found solar chargers. I remembered that they didn't keep the batteries charged (in fact the batteries died after a few days of not riding) and wanted to throw them away, but I was curious WHY they didn't work. I placed the solar panels in the sun, took out a voltmeter, attached the red probe to the red terminal and the black to the black. Solar charge showed -16 volts! Another solar unit showed the same readings. I switched red to black and black to red and got +16 volts! Somehow the manufacturer swapped the minus and plus wires. I put the device back in my van and the battery stayed charged. With ANY solar device like this, do yourself a favor and make sure the polarity is correct before using it or you could drain your battery instead of charging it. This simple test would have saved me a lot of frustration (and the need to restart dead batteries!) if I had done it from the start.