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Top 10 things to know about UPS battery storage life

Eaton offers many different types of UPS batteries, each with specific requirements that need to be met to maintain functionality. So what do you need to know to maintain performance of the most critical element of your UPS? 
1. Is battery storage life the same as service life?

No. Storage life, or shelf life, refers to the period of time when a battery is in storage.  During a battery’s shelf life, no current is flowing into the battery, which means there can be no corrosion of the positive grid inside the battery. Assuming Eaton’s standard operating procedures are followed, a battery’s shelf life does not impact service life performance or warranty.  Service life refers to the next phase a battery’s storage life cycle when it is installed in a UPS system and where current flows into the battery. 

Eaton follows strict standards to manage and maintain UPS battery life expectancy so that once installed, batteries perform to published specifications.

2. Why would a battery lose capacity on the shelf?

Batteries lose charge or self-discharge due to slight differences in local areas of the plates that discharge the battery. In effect there are tiny, little batteries, inside that are not open circuited and will discharge locally some of the active material. Self-discharge of the battery occurs continuously whether the battery is standing open circuited or operating in the UPS. When the charger is on, a portion of the float current (i.e. small current flowing through the battery) goes to overcoming self-discharge and keeps the battery fully charged.

Download a free handbook to learn how you can extend the life of your UPS battery, prevent costly downtime, and save time and money.

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3. What is the VRLA battery life?
The shelf life of a valve-regulated lead-acid (VRLA) battery is the length of time a battery can stand, open circuited, before it can no longer be recovered to full capacity with a single charge. Shelf life is determined by the length of time until the battery loses 40% - 50% of its initial capacity due to self-discharge. 

Battery date code chart for UPS products:


Date code identifier





C&D Dynasty




Enersys High Rate



YYDDD (Julian)



Yuasa / B&B


4. How will the shelf life and runtime be impacted if the battery has been in storage?

Proper recharging within the stated shelf life will maintain the runtime to that of a new battery. If a battery has lost significant charge in storage, Eaton will recharge the battery and add a new label noting the next “recharge by” date. 

5. If I’m a customer storing battery cabinets ahead of installation, what are my options to recharge the batteries in the field before the next required recharge?

If a battery system in the field is approaching the “recharge by” date and the UPS will not be installed before that date, then plans should be made to recharge the batteries. Please see next question on recharging batteries in the field. If the batteries are not recharged on time, the service life and warranty will be affected

6. How can batteries be recharged in the field before a UPS system is installed? 

UPS systems can be connected to a temporary feed to recharge the batteries. In some cases, external battery charging systems can be brought in to perform a refreshening charge. After its completion, the battery shelf life restarts and a new “recharge by” date should be established to manage recharging batteries in the future. 

7. How is battery life affected after a recharge?

After recharging is complete, the battery shelf life restarts and a new “recharge by” date should be established to ensure the battery shelf life is maintained through the next required recharge.

8. How does Eaton manage battery shelf life before shipping a product to customers? 

First, Eaton batteries may be recharged at the factory as part of standard operating procedure. Batteries that have been recharged will have a new “recharge by” label applied. Furthermore, Eaton guarantees that batteries shipped out of the factory will have at least a three month shelf life. 

9. What will happen if the battery system is not used or recharged by the date indicated?

Failure to put the battery system in service or failure to recharge before the “recharge by” date will result in a permanent loss of battery capacity as well as cancellation of the battery warranty.

10. Can any service provider recharge batteries? 

Many specialists support recharging batteries in the field, but by using Eaton service personnel, you are guaranteed that the battery manufacturers' guidelines are met to ensure your warranty is maintained. 

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