Join Date: May 2002
Location: East Coast
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Wet...cheap, rugged, most bang for the buck. Limits: Maintenance, subject to sulphation, can only charge or discharge at 15-20% of capacity so it takes a long time to charge after discharge. Must be EQ'd once every month or two to avoid sulfation. Self discharge of 10-15% per month makes winter charging or storage necessary.
AGM...rugged, no maintenance, can be charged 2 to 5 times faster depending on model, can be mounted in any position. Sef discharge rate of about 1-3% a month. Downside 3x more expensive, requires PRECISE charging system and MUST be brought back to 100% state of charge at least every week or two. Generally about 20% less cycle life than an EQUIVILENTLY built wet cell. They are not economical compared to wet cells EXCEPT in full time live aboard situations where the charging time advantage pays for the price difference in fuel savings and maintenance.
Gels...same advantages as AGM's but can be discharged deeper without damage. Cannot take the same level of charging current as an equivilent AGM but better than wet. Extremely sensitive to over charging and require different settings on an external regulator and battery charger. Can be quickly destroyed if overcharged. Not widely used in marine applications anymore.
Note...there are big differences in quality and price between various brands in the same TYPE batteries as well. The Wal Mart Special Wets are not the Same as Surette Wets.
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Last edited by camaraderie; 08-01-2009 at 10:40 AM.