supposedly, this is a good product to have if ur needing to keep ur truck battery topped off. my battery would not crank after 8 days of not driving because of those draws it gets while sitting. (all newer vehicles have some kind of draw from the battery with radio presets, alarm system, time clock, etc.)in my case, i wasnt driving my truck maybe once or twice a month so that the alternator could recharge the battery. when i went to crank it, it would just click. i installed this solar maintainer. the box stated that it keeps the battery in charging status, notifies you of when the battery is over 85% charged and then when its fully charged, it goes into a float mode. when the draws start draining the battery again, it kicks back on to charge. this is solar which means that it does not charge in the dark but will charge when its daylight even if there is cloud cover. well, it turns out that it wasnt doing any charging to my battery after all. i let it sit for about 3 weeks and when i unhooked it from the battery, i noticed that the lights were still on the maintainer stating it was charging...i went to crank the truck and it would not crank. apparently the lights were only lighting up on the panel to let me know that the sun was out. i ended up returning the product for a full refund to amazon and getting a jump starter instead.