But there’s more to consider than just the number of cycles. Because of their construction, gel-cell batteries are the most finicky about their recharge regimen, and in my own experience, improper charging is what kills them—and it can happen rather quickly, typically in one sailing season or less. So, if you want to go the gel-cell route, be prepared to upgrade your engine’s alternator to one with a remote, programmable voltage regulator. Also, make sure that your shore-power charger, if you have one, has a gel-cell setting or adjustable voltage levels for its various phases of charging. Any solar- or wind-charging units must be run through a charge controller that can handle the lower voltages required by the gel batteries.