【Function】Suitable for keeping vehicles/boat battery charged during the weeks unused. No need to disconnect the battery or have someone start the vehicle periodically. The indicator light on the back can observe the charging state. And it’s waterproof, you can safely use it outdoors(After experimental test).【Protection】The 10w monocrystalline solar panel uses trickle charging to charge the battery without causing overcharging. Built-in blocking diode prevents reverse charging without extra maintenance at night. Works even on cloudy days. As frosted surface, the panel doesn't need film protection anymore.【Solar Trickle Charger Upgrade】PCB upgrade and addition the function of reverse and overcharge protections.And you can test the open circuit voltage normally.ECO-WORTHY 10W solar battery charge your car battery more safely and efficiently.Be a good helper on your journey!【Easy to Install】Equipped with SAE cable, just plug the cigarette lighter into the port or connect the battery terminal posts with the alligator clip, and the connection can be completed within 3 minutes! Suitable for car, truck, boat, lawn mower, motorcycles, trailer, dump trailer, tractor, RV, van, camper, ATV, utility vehicle Battery etc.【Good Service】If you have any questions, please contact us. Your suggestion helps us improve!