Calculating Excess electrical capacity

# Thread: Calculating Excess electrical capacity

1. ## Calculating Excess electrical capacity

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.

http://www.powerletproducts.com/lear...excessCapacity

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.

Possible accessories:

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.

2.

3. You are right regarding the brake lights. They will only be a fraction of the 21 watts (each) as they will only be at 'park' light brightness while riding. Fans only come on in hot weather while stuck in traffic. Not necessary to factor in when wanting to wear heated clothing. Turn signals are intermittent so ignore them as you have done. By using HID headlights and upgrading any running lights, etc. to LED bulbs, there could be upwards of 100W of 'free' power that becomes available.

4. Originally Posted by schmii
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.

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.

Awesome, thanks for the write up!

My 125 only puts out 290 @ 5000, so I was definately using a similar process when calculating my theoretical available power.

I hadn't considered the fuel pump in my figuring, more so just lumped "bike misc." as a guesstimated amount, but truly don't know what really constitutes an accurate total.

5. Originally Posted by Talon
You are right regarding the brake lights. They will only be a fraction of the 21 watts (each) as they will only be at 'park' light brightness while riding. Fans only come on in hot weather while stuck in traffic. Not necessary to factor in when wanting to wear heated clothing. Turn signals are intermittent so ignore them as you have done.

By using HID headlights and upgrading any running lights, etc. to LED bulbs, there could be upwards of 100W of 'free' power that becomes available.

For my purposes, (Symtec grip elements) I also did not plug in the use of the fan. I don't recall ever seeing/hearing it come on in the middle of summer during heavy traffic, so for me, not applicable in this instance.

Absolutely! Exactly what I have done- swap in a 35W HID for my low beam, and replace all instrument cluster, centre position light, licence plate light, etc., with leds.

6. If you are adding electrical add ons get a volt meter as well. Keeping an eye on what your bike is doing voltage wise is a GOOD thing. It is a VERY good warning if something is wrong.

7. ## 2008 ZX-10r Alternator Output Wattage 440 Watts

As the subject line says. Took the dealer quite a bit of effort to find this out, so here is this little piece of info for all of you ZX10 owners.

440 Watt alternator output.

8. Originally Posted by dasein
As the subject line says. Took the dealer quite a bit of effort to find this out, so here is this little piece of info for all of you ZX10 owners.

440 Watt alternator output.
+1. a volt meter is all anybody needs to tell the tale. My old air head only puts out 280 w. on a good day so you want to keep an eye on the volt meter. My Escort x-50 radar detector has a built in volt meter that I display on my k13s. No worries there.

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