Dennis wrote:
Hi, I have a 10 year old First Alert FA-210 panel which shows LO BAT
off and on, but there is no zone number info. Sometimes the panel will
keep beeping until I press any key on the keypad to turn the beeping
off. According to the manual, it says it is due to low system power
condition. But I checked the AC power and it seems to be feeding the
correct voltage to the control box. Any clue?

Thanks
Dennis

C'mon guys...

Put a meter on the battery, disconnect the AC, monitor the battery for
one minute. At no time should the battery voltage drop below
(preferably get anywhere close to) 12 volts.

The panel periodically checks the battery. If you replace it, you may
have to wait quite a while before the LO Bat goes away.