Shared Knowledge

"Small 12volt Battery(s) Dead? - Put on Load to Test"

21 December 2017

Summary: small 12volt batteries can be charged 100% and even read 12volts DC or more but not correct battery problem you are having. Must put a 12volt load on battery to properly test.

Background:

Small 12volt batteries like those shown above are used in a variety of devices to include interruptible power supplies, security systems, home elevators and more.

When a device with a 12volt battery installed registers a battery problem or begins to act in some abnormal way, must remove battery and charge and test.

Charge? Perhaps power adapter associated with device has gone bad and is no longer trickle charging the suspect battery.

Hook 12volt battery to a battery charger and use "small battery" setting.

If charger says battery defective, replace.

If charger full charges battery, does not mean battery is good, have to test battery with a 12volt load of some kind.

Testing battery:

I have had small 12volt batteries test at 12volts and fully charge via a battery charger but still not work in a device or works for a short time.

Once you have charged a small 12volt battery, you must test it by putting a 12volt load on it. In my case, I use a 12volt driven air pump but any 12volt driven device will work. Might have to connect a short piece of wire to negative side of device connector to be able to connect to battery.

If battery is defective, it will only run load for a very short time. A good battery will run my air pump for minutes. A bad battery will run my air pump or less than one minute.

If battery fails under load, that battery must be replaced.

If battery does not fail under load, can reinstall but then must consider power adapter or perhaps some electric circuit in device is not properly charging or using the battery.

Battery Life:

From experience, have found small 12volt batteries have a like of about 4 years from date of manufacture. Not your install date. When you buy a new 12volt small battery search battery for manufacture date and buy one that is the newest or more recently manufactured.