In a message dated 10/23/02 5:53:39 PM, jrduke1@dslextreme.com writes: << Hello, Does anyone have advice on storing the battery on board the M17. I'm concerned about the build up of hydrogen gas. It isn't much fun removing it after every sail. I don't get a chance to go sailing very often and would like to leave the battery in the boat with an external float charger. Jerry Duke M17 #333 jrduke1@dslextreme.com >> Jerry, If your lead-acid battery is near the end of its useful life, I would recommend replacing it with either an AGM (Absorbed Glass Mat) or Gel Cell battery. Both are sealed, and will not off-gas unless severely overcharged (they have high pressure relief valves that, under normal use, never open); don't have acid to leak (some models can even be mounted on their sides or upside down); have very low self discharge rates (can be left long periods without charger); are entirely maintenance free (save for proper charging); and are more tolerant to more and deeper discharge cycles. The Gel cells are finicky about charging voltage. Most don't want to see higher than 14.1 volts (and thus a smart or adjustable charger is required). AGM batteries (which I favor) are more tolerant to high voltages, and share similar advantages to the Gel's. Both Gel and AGM batteries are more expensive and slightly heavier than lead acid types for a given group size. With proper regulation and cycling, they should far outlast the lead-acid, however. West Marine (among others) sells a full line of both Gel and AGM type. It is my opinion that the U-1 group size is the perfect battery for the M15, and perhaps a pair of these or a single group 24 would be appropriate for the M17. I stopped installing lead acid batteries some years ago. The Gel cells have improved over the years, and the more recent AGM's have given flawless service in every application I have tried so far (one solar/electric gate, two boats, two trucks, and a diesel generator). I can't see any compelling reason to use lead-acid types any more. Hope this helps, Scott Grometer, M15 #478 "bebe"