Checking Battery

Use a hygrometer.

I think you meant a hydrometer.

But as this is for a small UPS (12V battery) I would suspect the battery would be sealed.

The easiest way to test the battery is with the UPS cover removed, attach it's normal load and check the battery terminal voltage with the mains input turned off. But for gods sake be careful there will be 230V on the main boards.

Use the digital voltmeter and the number should be above 12V. 12.6 or even 13V is good. When you get exactly 12V, your battery is in doubt. It needs to check for recharging.

Normally, the battery now is equipped with indicator (Green: good,yellow: recharged, black: Broken).

That, too.

Hi,

My UPS has a built in system which warns me when the battery is getting low and advises what and when to purchase a new one. (APC is the supplier and it is a useful facility , especially as I can run 2 to 3 years without a change.

Good Luck

Sleepy

Do not confuse a lead acid battery with a ni-cad or other types.A lead acid battery does not respond well to deep discharge.The plates will get a sulphate coating, which is an insulator.It is almost impossible to remove this coating once present.The best thing for a lead acid battery is to keep it fully charged as much as possible, and do not allow them to sit in an uncharged state for a prolonged period.

The best indicator of the charge condition is by checking specific gravity.Testers are very cheap, and readily available, with an indicator bar showing condition.

Load testers are discussed elsewhere on this forum.

If the battery has removable caps to test the acid, use car battery testing equipment, mentioned in previous posts. If the battery is a sealed no maintenance car type battery, you can still use the load tester.

If the battery is a sealed gel type, hook it up to the UPS and unplug the UPS while it is switched on, with a normal load on it. The amount of time the UPS powers the load will tell you how the battery is doing.

I just replaced the gel batteries in one of my UPS units, one battery was no good, the other seemed ok. I replaced them both with new, will use the old good battery for bench testing other equipment. These gels have a limited life, usually start to swell as they die.

All batteries no matter what type, when fully charged, should hold that charge with no load on them for period depending on type- if the batt loses charge quickly it means short inside batt- which means batt finished. Ups usually have sla or gel cell batts- these batts usually charge up & hold 12.8v min over weeks with no load. The test for any batt is whether it can deliver current -if so batt is within serviceable range still. The current depends on type of batt & capacity of batt & job the batt has to do. Generally speaking a load tester for any batt puts a load on the bat while measuring voltage- if volts fall too low batt is finished in it's intended application. All batts have a limited life & a certain number of discharge/recharge cycles depending on type of batt- not treating batt correctly can reduce life significantly-eg over-discharge- leaving discharged- recharging wrongly-eg under charge or overcharge. If your batt measures 13v disconnected, it is probably good.

Kazengg,

It's hard to provide answers to ill-defined questions. Can you please specify manufacturer, model, etc? Even better, you could contact the manufacturer's tech support. They'll ask you the same questions, though, so be prepared.

No one mentioned the load that you are attempting to support with that UPS of yours.

At any rate I would suggest that you simply dsconnect the/one of (the) lead(s) to the battery & drop in a 12 volt lamp. Try and match the lamp current/wattage w/the load you are aiming to support. The intensity of the light emitted & the length of time that (level) of light is maintained can give you a reasonable measure of how well UPS will respond if really needed. Start test by attaching lamp before battery leads are disconnected... this provides a basiline for ideal performance. You may also (are you trying to support a computer?) simply watch you display (turn off computer) & see how long that thing will stay on. Carlos