Durable Motorcycle Tender AGM Maintainer 12V Battery Charger 12V 1AMP PowerStar batteries are shipped charged and ready to install. We offer a full 24 Month warranty. Our sealed motor sports batteries feature Absorbed Glass Mat technology (AGM for short). This design dramatically improves a batteries performance in the following areas: True sealed and maintenance-free design, you'll never have to check or add electrolyte again, unlike conventional batteries which require periodic fluid checks. Liquid-free AGM design, will not leak or corrode on expensive paint and chrome, and also eliminates corrosion around the battery terminals AGM batteries have less internal resistance which allows them to produce more discharge current (cold cranking amperage) vs. comparable conventional "wet" batteries, and AGM batteries also recharge faster Better resistance to both heat and vibration, a major cause of failure in conventional motorcycle batteries Much slower self-discharge rate, (3% vs.15% per month) means longer periods between battery recharging over periods of non-use, like winter months or vacations.