I've had my solar chargers (2 different chargers in differing strengths) for 3 years and they continue to work beautifully. I've only ever had one problem with them when we didn't get any sun for 13 days. The batteries went flat. A trickle charger re-upped the batteries and when the sun finally came out the chargers continued to do their magic. I love the solar chargers because I can't run power out into the 11 acres I own. The power is near the house, but the animals are all kept out in the forest away from the house, so power is not an option out there. I feel much safer knowing all my livestock is caged behind electric fences. I couldn't do that without the solar chargers.