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What Do My Batteries Want?

Members of the ISP-Tech list discuss the battery life of the average uninterruptible power supply (UPS) as they scour the Web for information on some strange blinking lights.

[October 23, 2002]

On the ISP-Tech list in October, JK asked:

"Anyone in APC land know what it means when the Battery Level indicater is flashing? Not the load, but the one on the far right that indicated the battery life? I have this happening on a Smart-UPS 1000RM and Smart-UPS 700RM from APC."

Members suggested a variety of possible causes.

[DD asked] "This might be a dumb question but is the uninterruptible power supply (UPS) turned on? A few years ago before we got generators I decided to shut the system down during a hurricane because the power was getting real flaky and I knew I would lose it for good soon. When I brought it back up I noticed the battery lights were blinking on the Tripp Lites. I thought at first that the batteries were weak and would recharge. When they were still blinking the next day I looked further and found out that that every UPS was turned off. They were still passing line power but the battery backups had been shut off. It turned out that one of the techs had turned them off when we shut down.

[GG added] "According to APC this happens when the UPS loses track of the amount of charge the batteries have in them. This can happen when new batteries are installed and sometimes when a power surge occurs. If the batteries are OK, discharging them by placing a load on the UPS and disconnecting it from the wall until it shuts down and then allowing it to recharge immediately will correct the problem. The flashing was originally designed as a warning to tell you when the unit was within two minutes of shutting down as a result of low power. The warning system, however, can be confused. This happens most often when new fully charged batteries are installed in the unit. Also do not forget to disconnect the shut down cable from the back of the computer if you are using one or you might cause the unit to shut down before the batteries actually discharge."

Several respondents discussed how long a UPS battery should last.

[JL began] "As I recall, that means the battery is nearing end-of-life, and you should order spares (especially if yours are more than a couple of years old). In my experience, average battery life for a UPS seems to be five years or less."

[JM replied] "Wow, I've never seen five years—you must live well. We get two-three years max, and we don't see many power outages or brownouts. Then again, if a battery that once held a system up for 20 minutees only lasts five minutes, I consider it dead. Recently, we made the decision to automatically replace all batteries every 24 months. It beats finding out during an outage that one doesn't last as long as expected, or has failed outright."

[BF noted] "APC will tell you to replace the battery every year, two at most. Then again, they make a lot of money off of those batteries. I recommend doing a good solid load test at least once a month. If you start seeing a huge drop in uptime when running off battery, buy more!"

JK reiterated the question, with the twist:

"OK, then what does it mean if that light is flashing, but the battery is brand new?"

JM found several answers on an APC FAQ:

"Try this page."

—End