Hello guys

This is puzzling me and some others that I asked as well. Here is the thing.

When I switch on my AC and it starts kicking in my amps goes up until 60 amps and than usually settles around 43 amps. Which is fine I have a 100 amp alternator. Then I start my taxi and the amps pretty much stays the same (with AC on).

But when I am doing a run-up my amps goes all the way to 85amps…hovers there a little and then settles back to around 70amp @ 1700rpm

In flight when the AC is running (cruise) my amps are around 44amps. Sometimes it goes to 60amps, this is when the AC kicks in again.

The puzzling part is, why it goes all the way to 85amps and than goes back again on the run up? I hope to trigger some Ideas here.

I am having problems that my breaker from the AC pops after about 15-20min after start.

I will speculate that you are drawing more power from the battery just after start than the alternator can produce at idle RPM. This discharges the battery during warm up/taxi. When you run up the engine, the alternator output increases to the max allowed by the regulator for a short time until the battery recovers some of its lost charge, then the regulator reduces the output somewhat to cover the A/C load, plus other accessories and some to continue to re-charge the battery.

The in-flight amerage represents the “steady state” load to carry your A/C and other powered accessories, plus a “trickle charge” for the battery. BTW, it sounds like you have an electrically-driven A/C compressor? I ask this because this is significantly more amperage than an engine-driven compressor based system should draw (mine uses about 12 amps with all components running; less when the condenser fans are off (normal ops).

Enough for “triggering ideas.” I’d contact the A/C manufacturer to see what the starting and steady-state electrical loads should be. Don’t be tempted to just change out the circuit breaker for a larger one…this is a seriously bad idea until you confirm that the system, and especially the wiring, can handle the higher current.

Bob