I read in another forums a rider was concerned about their excess power to add run heated gear and I got curious what power is typically available.
A short answer is ~100 watts but lets take a look at some steps to calculate that.
The first barrier was understanding amps watts and volts explained with this equation:
Watts = Volts x Amps
From my service manual ST1300A:
Service manual alternator output: 742 watts @ 5000 rpm (assuming 14 volts might be based on something else)
Main fuse off the battery: 65 amp (is the main fuse a concern?)
Assuming 14 volt 5000rpm: 742 watts / 14 volts = 53 amps (nope)
14 volts 5000 rpm: 742 watts
12 volts bike off: 636 watts
13 volt slow idle: 689 watts
Typical voltage on a bike seems to be around 13.5 so I ballpark 700 watts available in a realistic scenario.
Time to lookup a breakdown of electrical peripherals from my manual:
54 watts - Quick charge (11 watts slow charge)
25 watts - ABS computer
42 watts - Brake lights (there's 2 assume 21 per)
10 watts - Instrument Cluster
25 watts - ECU bike computer
100 watts - Radiator fans x2 assume 50 watt per fan
50 watts - Fuel Pump
10 watts - Position lights (small lights in headlight cluster)
90 watts - Headlights (two lights assume 45 each)
50 watts - Ignition (not sure what this is unique to EFI?)
42 watts - Turn signal front + back (84 watt 4-way flasher)
Total 498 watts
This figure is running with the brakes, turn signal, charging with fans running nothing more.
Total 413 watts
This figure is a slow charge with the fans and nothing else on. I can safely assume the bike will draw ~450 watts average idling around town on a hot day.
Heated gear based off Gerbing's website:
77 watts - Jacket Liner
54 watts - Vest Liner
44 watts - Heated Pants
27 watts - Heated Gloves
Heated Seat based off Corbin Specs:
54 watts - Single panel rider/pillion
Heated Grips based on Symtec elements:
40.5 watts - 3A x13.5V based on specs
35 – 100 watts - Aux lights each
40 – 60 watts - Laptop
1 – 3 watts - Cell Phone
1 – 3 watts - Radar Detector
2 – 6 watts - GPS
1 – 3 watts - Portable Music
Hopefully this breakdown can answer if one can add heated gear, stereo, or additional lighting to their bikes. It seems all other electric accessories don't draw significant power.