me 7 years so far. Most of that was cruising and living aboard in Mexico. This last year I have been home. I replaced them in Feb. of 08 in Las Hadas, Mexico. It took us two weeks for them to arrive from the states and every night while we were waiting for the replacements to arrive they would go dead at about three in the morning and the battery alarm would go off. One of us would have to get up, fire up the generator and sit with them until they took a charge. During the day the solar panels and wind generator would hold them up but night would come and so would the baby sitting. I'm on my third set and the only thing I can say negative about them is that when they fail you have almost no warning. One day they work and the next they don't. It's not like you can test them with a hygrometer like wet cells. That said, I highly recommend them because they are virtually maintenance free for 7 or 8 years. I don't have any experience with the other brands.