What is the Lifespan of a Typical UPS Battery?
The typical time frame for replacing a UPS battery is between 3-5 years. However, sometimes the answer is "it depends".
The kind of load that the UPS battery is subjected to and the conditions can make a difference. Sealed lead-acid batteries (SLA) are typically damaged by a full drain. If you do regular load tests that drain them most of the way or if you have lost all power for extended periods of time, causing the battery to automatically switch on to power the server, then it may be a smart idea to replace them at 3 years.
If they have generally stayed above the 80% charge for their entire lifetime, in a location with a nice even temperature, you can expect them to be functioning well closer to the 4 or 5-year mark.
Don't Guess - TEST
Following the manufacturer's instructions, create a maintenance plan for your UPSs. The UPS batteries that last the longest, and provide the best performance, are those that are being managed and cared for. Make sure your plan is simple, consistent and proactive.
Testing will offer the best way to get an accurate picture of the fitness of the UPS. While sealed-lead acid (SLA) batteries are called "maintenance free", this only means that you no longer have to add water to them. Maintenance and regular testing are still recommended.
SLA batteries will self-discharge. Full capacity may not be possible is if the battery is not recharged periodically. Typical monthly discharge is 3% per month. A good idea is to check and recharge your unused SLA every three months.
A swollen battery is a sure sign that your unit needs to be serviced. Overcharging a battery may result in a swollen battery. When excessive current flows into the battery after the battery has reached a full charge, the battery will heat up and cause it to expand. A swollen battery should be removed from the system as soon as possible.
Inspecting the battery regularly will also help you notice when leads may be starting to corrode. Those can be cleaned, or the battery can be replaced.