What happens chemically inside a re-chargable battery that eventually causes it to no longer hold a charge?

EoGuy

The ions get tired. Dec 21 06, 8:57 AM

zbeckabee

Direct Quote: "When the active material in the plates can no longer sustain a discharge current, the battery "dies". Normally a battery "ages" as the active positive plate material sheds (or flakes off) due to the normal expansion and contraction that occurs during the discharge and charge cycles. This causes a loss of plate capacity and a brown sediment, called sludge or "mud," that builds up in the bottom of the case and can short the plates of a cell out. In hot climates, additional major causes of failure are positive grid growth, positive grid metal corrosion in the electrolyte, negative grid shrinkage, buckling of plates, or loss of water. Deep discharges, heat, vibration, and over charging accelerate the "aging" process." http://www.optimabattery.freeserve.co.uk/batteryFAQ/carfaq2.htm Quote: "The rechargeable battery is a corrosive device that gradually loses its ability to hold charge as part of natural aging, incorrect use and/or lack of maintenance. The unusable part of the battery that creeps in is referred to as ‘rock content’." http://www.buchmann.ca/Chap11-page2.asp Dec 21 06, 11:30 AM