Alarm System Battery Replaced

[wingnut771]

I have an alarm where the battery starts off fine, then over 3 months that battery seems to die (get low battery alerts). This despite the inverter always powering the alarm (as far as I know). I was told only parts of the kitchen are excluded from inverter power.
Long story short, I have a spare battery in the house and charge it in my little UPS for my desktop PC. My plan is to rotate it into the alarm. Just don't want to kill it too
PS I have already had the alarm company techies in and they replaced the charger early last year

Double check that its connected to the inverter.

 

[impracticaldogg]

I have a multimeter but I'm dof at this. I would measure the voltage across the battery terminals while attached to the alarm. With mains supply to the house.
Then switch off the mains and check the voltage again. If there is no supply from the inverter the voltage should drop.
Sound ok?

 

[wingnut771]

I have a multimeter but I'm dof at this. I would measure the voltage across the battery terminals while attached to the alarm. With mains supply to the house.
Then switch off the mains and check the voltage again. If there is no supply from the inverter the voltage should drop.
Sound ok?

I can say already without a multimeter that the voltage is dropping during power failure, that's what's ruining the battery over 3 months imho.