Keeping batteries stored for a long time actually causes them to age. During long idle periods, the battery cells are subjected to self-discharge and decomposition. A sealed lead-acid battery (SLA) is equipped with a design that prohibits electrolytes to leak from the cells. Sometimes the seals are broken, however. SLA batteries are also prone to water permeation which causes a permanent damage to the battery. It is important to ensure proper storage of the SLA battery in order to prolong its life.
A sealed lead-acid battery can be stored for up to 2 years. During that period, it is vital to check the voltage and charge it when the battery drops to 70%. Low charge increases the possibility of sulfation.
Storage temperature greatly affects SLA batteries. The best temperature for battery storage is 15°C (59°F). The allowable temperature ranges from –40°C to 50°C (–40°C to 122°F). The table below describes the sealed lead-acid battery discharge at different temperatures after 6 months of storage:
| Temperature | From Full Charge |
| 0°C | 97% |
| 25°C | 90% |
| 40°C | 62% |
| 60°C | 38% |
Guidelines for Storing A Sealed Lead-Acid Battery:
- Store the battery after fully charging it
- Store it at room temperature or lower
- Remove the battery from the equipment
- Charge it every 6 months, or as recommended by the manual
- Avoid deep discharge
- Choose proper float voltages to avoid sulfation and corrosion
Bringing Power Back To A Stored Sealed Lead-Acid Battery
There are many ways to power-up a stored sealed lead-acid battery. Two common ways are topping charge and equalizing charge. A topping charge can be performed by fully charging the SLA battery, removing it from the charger for 24-48 hours, and then applying charge again. The process must be repeated several times in order to check the full discharge and recharge capacity of the battery.
Another way to power a stationary sealed lead-acid battery is by performing an equalizing charge. Equalizing charge can also be considered as forced overcharge, which is keeping the battery charged for an hour or two after reaching a full charge status. This process may remove sulfation in the battery, which is likely formed during low-charge conditions when it is idle.
Related Posts:
What is a sealed lead-acid battery?
Image Source: PNNL
