When not in use, it is typical for AGM models to naturally self-discharge at a rate of 2% per month at 25ºC (77ºF). The rate of self-discharge decreases at lower ambient temperatures and will increase significantly when stored in consistently warmer ambient temperatures – up to 50% faster at 35ºC (95ºF).
AGM batteries should be stored in a cool (above freezing), dry location unpackaged or in the original packaging. Avoid placing the batteries directly on concrete floors. When an AGM battery is stored for extended periods, a refresher or boost charge should be performed to avoid excessive discharge and possible freezing in very cold temperatures. A refresher charge every 3-4 months is ideal.
Procedure:
1. Boost the battery at the recommended Absorption voltage (2.45 VPC) at a charge current equivalent to the C/5 rate of the battery.
2. When the battery reaches Absorption voltage, maintain charge for 3 hours.
If the batteries have been stored for <6 months, perform 2-3 charge/discharge cycles at the recommended charge rates to recondition. (see Battery User Manual)
If the batteries have been stored for >6 months, additional charge/discharge cycles may be necessary to get the batteries to reach full capacity.
Damage or failure due to excessive self-discharge, extended storage without boost charging and/or inadequate charging will often require replacement which is not covered under the terms of the manufacturer warranty.
For more information on battery storage and installation, please refer to the Battery User Manual.