I've had so-so luck with Westco from the Boneyard. They state a 1 year no questions asked warranty. I had one fail prematurely, Boneyard had record of purchase and asked for photo of Battery. New one was delivered in 2 days, no questions asked. I greatly appreciate that level of customer service and tend to reward any vendor for same. FWIW, the replacement has been in the bike for 3 years, parked in a carport through Pennsylvania winters always on an Accumate charger also from the Boneyard. I have no affiliation to the Boneyard, but as I said, they been berry-berry good to me!