Multimeter is probably out of battery.

Dont get so hung up on the multimeter reading, your only running a 2 ch amp your not going to be stressing the charging system at all. I run stock alternator and 2 amps(800 rms) and have no problems, you will be running 150-250rms which is nothing to the charging system.


As drifter said amps dont need 14.4v to run, for example when my car is off and battery is at about 12.5V both my amps still play just fine.