Hello,

I have a 12-volt sealed lead acid battery, not a car battery, which I
use occasionally, which I charge with a 3-amp smart charger.  

Does anyone have either an idea for a circuit or a source for an
audible device which will let me know when the battery's voltage drops
below 9 volts?

I have a 12-volt motor out of a computer fan.  But I don't know what
the minimum voltage is on which it would run.

Thanks in advance for ideas.

Don Roberts