SRNDT and SRNDTI Uninterruptible Power Systems (UPS) utilize internal battery packs to provide power when the main AC power source is lost. These battery packs have a service life and require replacement when performance is compromised by aging. Below are some Frequently Asked Questions concerning the batteries in UPS systems, courtesy of Clary Corporation.

 

What happens when Batteries age?

Batteries lose capacity as they age. That is, they can store and deliver less energy as they get older. It is true that batteries can actually gain a little capacity for the first year of operation, but after that the lost capacity is significant. After 3 years, some of the batteries in the UPS will have lost 20% of their capacity.

The lost capacity in the battery pack will result in lower UPS system backup times. For example, if the UPS system can support 10 minutes of backup with your current load, in 3 years time this same battery string might support only 8 minutes. This may or may not be important in your application.

What is the Service Life of my Battery Pack?

Typically 3 years of shipboard use, depending upon many variables. The most important variables are load and initial battery capacity (sizing), temperature, charging history, discharging history, and storage.

  • Load and Battery Capacity.  If the load is high relative to the battery sizing (resulting in shorter run-times), then there is little safety margin for reduced battery capacity through aging. Therefore, battery packs will require more frequent replacement. If, alternatively, the battery pack is oversized and considerable battery capacity loss (through aging) can be tolerated, then the pack will require less frequent replacement.
  • Temperature affects the service life. Higher storage temperatures age the batteries more rapidly. Store the batteries in room-temperature environments. Deploy battery packs in room-temperature conditions for best performance.
  • Charging History. Best battery life is obtained by storing batteries in a fully charged state. Allowing the batteries to self-discharge during storage will adversely affect their life. Allowing a battery to entirely deplete itself can permanently destroy the battery.
  • Discharging History. Repeated discharge to empty and re-charge cycles reduce service life.
  • Storage. Batteries should be stored in a room-temperature environment in a fully charged state. If this is not possible, recharge the batteries at least every 3 months to prevent damage. Do this by powering up the UPS, starting the inverter, and letting the batteries charge for at least 24 hours.

 

How can I add to the Service Life of my Battery Pack?

You can add an additional external battery pack. This will increase your available capacity relative to your present load (extending your available run-time). This will allow loss of capacity occurring through battery aging to be tolerated without impact on your application.

What are the manufacturer’s recommendations concerning Battery Replacement?

For most applications, the manufacturer recommends replacing your batteries every 3 years on a preventive maintenance schedule. Replace the batteries before they have lost the capacity required in your application.

When batteries are replaced in the field, please watch for these items:

  • Screws or washers left loose in the UPS. These will short out internal circuitry and cause the UPS to malfunction.
  • Reattaching the batteries in the proper manner.
  • Use factory supplied batteries. Other batteries may have: (a) the wrong physical size and cause trouble with mounting, (b) wrong sized or styled connectors, causing wiring to become detached, (c) dissimilar capacities or ratings, causing the string to perform poorly immediately or over time.

 

How do I order a Replacement Battery Pack?

Order replacement battery packs from:

NOVA Power Solutions

Phone:  1-800-999-NOVA

Web:    www.novapower.com

Can I use non-factory supplied batteries?

In emergencies, yes. Otherwise, we prefer you do not. Use factory supplied Battery Packs to assure proper fit and operation.

Other batteries may have: (a) the wrong physical size and cause trouble with mounting, (b) wrong sized or styled connectors, causing wiring to become detached, (c) dissimilar capacities or ratings, causing the string to perform poorly immediately or over time.

How do I know if my Battery Pack is depleted?

Your pack is depleted if:

  • You fail to obtain the required battery run-times,
  • The Replace Battery LED is illuminated,
  • It has been 3 years since the battery pack was last replaced,
  • The UPS fails to Cold-Start (on battery power),
  • The UPS fails to provide any battery backup when utility AC power is lost (users often report this as “unit fails to hold load”).

 

What does the internal battery self-test routine really do?

The self-test routine determines if there has been a serious defect introduced into the battery string. The routine will not determine the percent of capacity lost through aging. This is accomplished by switching to battery backup power on a pre-determined interval (typically 40-200 hours) or by depressing the “Test” button on the front panel for 2-3 seconds.

What does the “Replace Battery LED” mean?

The UPS has determined there is a potential issue with the Battery Pack. Replace the batteries as soon as possible. If this condition was reached in error (perhaps you turned the UPS on when the batteries were not yet connected), this can be corrected by power-cycling the UPS. The Replace Battery LED is a “latching” indicator and stays illuminated until power is cycled.

How can I be assured my Batteries are always fully charged?

  • Keep the UPS on (and the inverter running), and the UPS will automatically keep the batteries charged.
  • If the UPS is in storage awaiting deployment, turn on the UPS every 3 months, start the inverter (by depressing the Load On/Off button), and let the UPS charge the batteries for 24 hours.
  • It is best to order the Battery Pack so it will be received just prior to installation. This will minimize your storage requirements (and the required charging tasks).
  • If the UPS has been run on battery and the batteries discharged, please turn the UPS back on when utility AC power is restored (and the inverter turned on) so the batteries can be recharged before next usage.

 

Is it OK to leave my Battery Pack Discharged?

Absolutely not. If you are storing a Battery Pack in the discharged state, you will increase the risk that the battery will be damaged by the subsequent self-discharge.

How long does it take to recharge my Battery Pack?

This is dependent upon the depth of discharge and the rate of the charger. As a good rule of thumb, please allow 12 hours for charging for a typical Battery Pack. 24 hours to completely and fully charge a pack should always be adequate.

What powers the UPS Battery Charger?

The UPS battery charger derives its power from the inverter. Therefore, the UPS inverter must be on for the battery charger to operate and charge the batteries. The inverter is turned on by depressing the Load On/Off switch on the front panel. The status of the inverter is indicated by the “INV” LED on the front panel.