Also keep in mind that although your alternator is capable of putting out 180 Amps (I have a powermaster that is 180 amps for the EFI and lots of lights up front) it won't necessarily be doing it all the time because of the, in most cases today, built in regulator that will only provide the amps the system needs. So if the battery is dead and you have all of your lights on and the A/C blower is on high and you have a compressor plugged into the 12V socket, then yes the ammeter will be pegged. Otherwise, no, it will only show what the system is demanding. Volt meters have become the norm because of this: the system should be at around 13.5-14v all of the time. Also, an ammeter is OK as long as it is OK, but if it should short out or be damaged, you can have real problems.