Alternator Output Calculator

Calculate your electrical load and determine if your alternator has sufficient capacity.

Alternator Specifications

Alternator Rating (Amps)

System Voltage

Headlights (Watts)

HVAC Blower (Amps)

Fuel Pump (Amps)

Ignition System (Amps)

Audio System (Amps)

Other Accessories (Amps)

Aftermarket Additions (Amps)

Light bars, winches, amplifiers, etc.

Upgrade Recommended

Total electrical load: 86.3A (1243W)

Headlights8.3A

HVAC25.0A

Fuel Pump8.0A

Ignition10.0A

Audio20.0A

Accessories15.0A

Total Load86.3A

At Idle (~700 RPM)46A output

-40.8A available

At Cruise (~2500 RPM)85A output

-1.8A available

At High RPM (~5000+)124A output

+37.2A available

Your alternator cannot keep up at idle. Battery draining at 40.8A.

Estimated time to flat battery: ~1.5 hours at idle

130+ Amps

Minimum recommended for your load with 50% headroom

Upgrade Options:

250A AlternatorSuitable

300A AlternatorSuitable