Observe the following conditions when the battery needs to be stored.
Ambient temperature: -15°C to 40°C (preferably below 30°C)
Relative humidity: 25 to 85%
Storage place free from vibration, dust, direct sunlight, and moisture.
Self-discharge and refresh charge
During storage, batteries gradually lose their capacity due to self-discharge, therefore the capacity after storage is lower than the initial capacity. For the recovery of capacity, repeat charge/discharge several times for the battery in cycle use; for the battery in trickle use, continue charging the battery as loaded in the equipment for 48 to 72 hours.
Refresh charge (auxiliary charge)
When it is unavoidable to store the battery for 3 months or longer, periodically recharge the battery at the intervals recommended in the table below depending on ambient temperature. Avoid storing the battery for more than 12 months.
Residual capacity after storage
The result of testing the residual capacity of the battery which, after fully charged, has been left standing in the open-circuit state for a specific period at a specific ambient temperature is shown in the figure below. The self-discharge rate is very much dependent on the ambient temperature of storage. The higher the ambient tempera- ture, the less the residual capacity after storage for a specific period. Self-discharge rate almost doubles by each 10°C rise of storage temperature figure 4.
This information was obtained from the Panasonic Sealed Lead Acid Batteries Technical Handbook, 2018. It applies to most sealed lead acid batteries.