How long can a UPS battery last when unplugged?

[VirtualLarry]

Just wondering. I have an APC BX1500, that was last plugged in in Feb. I forgot to plug it in at my new place (no need for it), and when I realized that I probably need to charge it before it died completely, I plugged it in and now the battery fault light comes on.

I guess the battery is toast, and needs replacement?

 

[Lemon law]

Have you tried leaving it plugged in for awhile and trying it again?

Some types of batteries last longer when taken through a set of charge discharge cycles, but I am not sure how well it applies to sealed lead acid batteries typical of UPS applications.

But if your UPS battery was fully discharged in just 10 months or so, the same would apply to UPS's that leave the factory and are still unsold 10 months later.

 

[wirednuts]

if you just unplug a ups and store it though the battery will be drained in a couple hours. and if left flat for 10 months, any type of lead acid (or any battery really) will be toasted.

and even if you did fully turn off the ups before storing it, you should plug it in every few moths to recharge the battery.... because all batteries drain themselves without load (seald lead acid batteries last longer, but if youre pushing a year your pushing too far).

 

[Lemon law]

if you just unplug a ups and store it though the battery will be drained in a couple hours. and if left flat for 10 months, any type of lead acid (or any battery really) will be toasted.

and even if you did fully turn off the ups before storing it, you should plug it in every few moths to recharge the battery.... because all batteries drain themselves without load (seald lead acid batteries last longer, but if youre pushing a year your pushing too far).

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I am the last man on earth to claim any UPS expertise, but I have recently bought two of them, one made by APC, and one made by tripp-lite.

And I note there is a difference in design between the two.

On the Tripp-lite, once you shut down the power, there is no AC power to any of the eight 3 prong outlets, 4 of which are battery and surge protected, and the other 4 are omnly surge protected.

On the APC UPS, using the UPS on off switch only cuts AC power to the four 3 prong outlets that battery and surge protected, but not the four only surge protected ones.
A design I do not like. And unlike the tripp-lite UPS that arrived with the battery connected, the APC model arrived as shipped with only one connected and required the end user to connect the other terminal before use.

Which leads me to speculate, that for 10 month's, not only was our OP's UPS unplugged from wall power, the 4 only surge protected APC outlets had one or more live devices plugged into it that drained the battery dead dead and deader. Which may not have happened with a tripp-lite type design

 

[Lemon law]

Sorry accidental double post.

 

[VirtualLarry]

Which leads me to speculate, that for 10 month's, not only was our OP's UPS unplugged from wall power, the 4 only surge protected APC outlets had one or more live devices plugged into it that drained the battery dead dead and deader. Which may not have happened with a tripp-lite type design

No, there was nothing plugged into it either. It was just sitting in a corner.

 

[Lemon law]

Thank you for the update Virtual Larry and there goes my theory. Meanwhile, has the battery come back to life after being plugged into wall power?

And one more question, if the UPS is again plugged into the wall, and the computer is again plugged into it, will your computer boot and continue to function on raw AC wall power, even if your UPS hoots hollers and gives alarm messages? Without a functioning battery the UPS can't protect your computer from an AC power outage for a single millisecond, but for the most part AC wall power is reliable.

 

[westom]

No, there was nothing plugged into it either. It was just sitting in a corner.

SLA batteries have a short shelf life. If left without a recharge for more than one to three months (although it might hold a charge longer), then these batteries can dischargem - destructively.

Unlike other batteries, these type batteries fail permanently if left discharged.

 

[MarkGinger]

SLA batteries have a short shelf life. If left without a recharge for more than one to three months (although it might hold a charge longer), then these batteries can dischargem - destructively.

Unlike other batteries, these type batteries fail permanently if left discharged.

This is absolutely true. Unfortunately if you leave the batteries sitting around unplugged for more than a few months they will drain to a point of no return. Your best bet is to buy a new set.

 

[Modelworks]

Remove the batteries and with a meter check the voltage on them. If the voltage reads less than 11 volts with no load they are in bad shape. I have restored batteries but it takes more time than most people want to bother with. It involves using a charger that puts a higher than normal charge current through the batteries for very brief periods in order to try to loosen any crystal deposits on the plates .

Sometimes it works , sometimes not. Depends on how bad the batteries are. Out of about 20 dead batteries I have recovered about 14 of them that were assumed to be bad. Mostly it was from non use or storage on shelves for long periods. My current set on the ups now is over 7 years old which is a really long time for SLA batteries but I keep them well maintained.

 

[westom]

It involves using a charger that puts a higher than normal charge current through the batteries for very brief periods in order to try to loosen any crystal deposits on the plates .
Sometimes it works , sometimes not.

Tried that numerious times. Worked on NiCds. Never worked on SLAs. Please elaborate on how/why you had success.

 

[Modelworks]

Tried that numerious times. Worked on NiCds. Never worked on SLAs. Please elaborate on how/why you had success.

It really depends on the battery and its construction. It has to be ones that have liquid acid contents and are valve regulated. The ones I had good success with are panasonic and yuasa.
The npx models recover well
http://www.yuasabatteries.com/industrial.php

The gel cell type are paperweights, I wouldn't even try to recover those.
What you are looking for are the ones that are as close to a car battery as possible but in small form.

It is more than just sending a single pulse like on NiCd batteries. You have to modulate the power at around 2-4Mhz . It sets up vibrations in the plates that cause the deposits to break free and dissolve back into the acid and lets the plates contact the acid instead of being isolated from it.
Some people add the chemical EDTA to do the same thing but then you have to open the cells, add back acid and it can be a lot of work.


There are some commercial models sold as desulfators, but the one I use is a high current home made version tailored for the smaller sla batteries.