Article [13] ST1300 - Excess Electrical Capacity

I read in another forums a sportbike 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/learningCenter/excessCapacity

A short answer is ~100 watts but lets take a look at some steps to calculate that using my ST1300A as an example.

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 making several turns.

Possible accessories: ~250 watts available

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.

Re: ST1300 Excess Electrical Capacity

You might want to add the Stebel which takes 15 to 20 amps? ...Watts?

Hum...no wonder my alternator blew last year when I had my heated liner and gloves, twin driving lights (55w each), Autocom with MP3 player all going and then beeped my dual Stebels! 4: (I've since removed one of the Stebels, two wasn't any louder then the one anyway...)

Re: ST1300 Excess Electrical Capacity

You are assuming heated clothing at full heat, which I havent ever needed yet. I understand listing everything you did, however we need to ask how often all of those things listed will be on at once. I probably run a little more than I should but I am also aware of the fine line Im am crossing. At times we ride 2up with gerbings keeping us warm, heated grips on, 110 watt Piaas running, GPS playing tunage. However if Im in town and slowing to an idle my Piaas are always off, I dont use them in town. I also make sure I shut the bike off with the key so the Gerbings dont drain the battery when I stop for fuel.

Important Note: After '07, the alternator is rated: 675 watts @ 5000 RPM So downsize accordingly (this is from the Honda Service Manual)

In standard electrical installations (residential and commercial) we use something called demand factors. This is a multiplier (aka fudge factor) that takes into account that very few items draw current at a steady rate. For example, on your bike the radiator fans will kick on and off as needed (probably not very much when you are cruising at speed), the blinkers run for only 30 to 45 seconds, heated clothing is not always run on high, brake lights flash on and off. The reality of electrical usage allows us to run more farkles than the calculations might suggest. And, to forestall a question, I'm sorry, I have no such fudge factor for our bikes - I'm grappling with that myself.

SMSW said:

675 watts @ 5000 RPM So downsize accordingly

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That's like 90 mph I think. I'd be upsizing!!! to some serious winter gear.

You'll need some electric capacity to run serious heating at those windchill temperatures. I had my gloves on full and my jacket to almost full running 80mph on a 0? morning like today, I even turned my socks on. You slow down to sub 50mph coming off the interstate and it feels like you just crossed into Florida.

I'd like to see a power/rpm graph for this thing.

Radiator fans 100 Watts. We'll there you go. If it's cold enough for heated clothing the radiator fans should not be running.

For reference, I have a BMW R1200. It has everything that the ST has except for a radiator fan. The alternator produces a maximum of 840 watts and the bike has factory heated grip, two heated seats and two 12v plug ins for heated gear. Pretty sure the ST can handle radio/heated grips, etc without too much strain.

I may be wrong about this, but I always assumed that the battery was able to provide all of the necessary power, regardless of the output from the alternator. I assume that the battery has a limit, but I assume it is much higher than the output of the alternator - it has to be capable of operating the starter motor.

If there is too much demand on the battery at any one time, then the alternator will be able to recharge it when the demand is reduced. If the demand always exceeds the capacity of the alternator, then the battery will gradually go flat during a ride.

A lot of assumptions there- i have never investigated properly.

But I reckon that putting on loud horns and heated gear isn't going to be a big issue. The big problems arise when the existing cabling is expected to cope with the extra components. There is some spare capacity on some fused circuits, but not much - so extra cables and fuses need to be provided for these. I avoid using the bike's chassis for earth connections, and install a single separate high current earth lead to the battery terminal, and tap into this. That way, any poor ground connection that develops elsewhere in the system isn't going to result in my add-ons finding a way back to earth through any of the bike's multi-way ground connecting blocks - which would melt under the extra load.

T_C said:

That's like 90 mph I think. I'd be upsizing!!! to some serious winter gear.

You'll need some electric capacity to run serious heating at those windchill temperatures. I had my gloves on full and my jacket to almost full running 80mph on a 0? morning like today, I even turned my socks on. You slow down to sub 50mph coming off the interstate and it feels like you just crossed into Florida.

I'd like to see a power/rpm graph for this thing.

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Good point! It would be very difficult to ride at that speed in very cold conditions. Plus there is a speed limit (70 mph in most states). A more realistic speed for cold weather (say between 50-60 F) would be around 3500 - 4000 rpm. Translates to about 65 -75 mph indicated.

etalors said:

Good point! It would be very difficult to ride at that speed in very cold conditions. Plus there is a speed limit (70 mph in most states). A more realistic speed for cold weather (say between 50-60 F) would be around 3500 - 4000 rpm. Translates to about 65 -75 mph indicated.

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Just completed bun burner gold ride this morning. 1500 miles 22 hours and sadly it couldn't keep my jacket, gloves and pants going. Fyi it was about 50 degrees. Van I update my alternator? I have a 2005.

I have ridden 12 hour days with my Gerbing gloves and jacket liner on the whole time and never had them be not hot enough. When you say that you could not keep them going what does that mean?

Before yesterday I never have had issues running my gloves and jacket. Yes i added the pants. The last couple hundred miles it would all stop working. If I ran two out of 3 it seemed to heat up fine. It's like it was to much draw.

Disconnect them all, and with the bike running, measure the voltage at the battery. It should be about 13.5-14.5 volts. Connect your heated gear (turned on) one at a time and monitor the voltage. If it falls below 13, you're drawing too much current. And I've never heard of anyone needing to, or upgrading the ST1300 alternator.

Could the battery be weak and contribute to the issue?

Verizoncellular1 said:

Could the battery be weak and contribute to the issue?

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Yes, but if the bike is starting ok, my guess is it's not likely the battery. Measure battery voltage during starting, shouldn't drop below 9.0 volts. This can be hard if it starts quickly, so you could pull the plug wires to prevent it from starting, although it will likely flood a little, so may be a little hard to start next time. Alternatively, pull the battery and have it load tested at an auto parts store.

Verizoncellular1 said:

Could the battery be weak and contribute to the issue?

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As paul said if it starts ok the battery is probably not the issue. Once the charging system kicks in all should be handled — handily.

Your charging circuit and all your gear's connections should be checked for electron integrity. Solid clean shiny etc.

If the charging circuit is ok and all your gear's connections likewise then it would seem the fault might lie in your gear. You say 2 out of 3 and they heat OK. Have you tried all the combinations of the three? I don't think the alternator can be updated/upgraded only repaired/replaced if that's even necessary at this point.

The "stopped working" part is curious. Usually a really excessive draw will pop a fuse. Without a blown fuse or some kind of circuit breaker (I put a bunch in my GL1000 years ago) I don't see how heated gear stops working but starts back up when you remove one from the equation.

Unless may there's a voltage drop somewhere that means they are "working" but just not heating enough for you to notice.

Alternator output and then gear connections is where I'd start. It wouldn't hurt to check the battery. Always nice to what's what there. But I think that's unrelated.

If you are drawing too much juice while riding, the battery will make up the difference, discharging as it does so. Eventually you will stall the bike. A more likely reason for your problem is a voltage drop to the controller (heat troller) of your heated gear causing it to shut down. My guess is you have either a faulty connection or undersized wires feeding the controller, either from the battery or quartet harness or some other source.

A shut down caused by insufficient voltage is designed into many controllers so the unit shuts off when you turn the bike off - it cannot drain the battery. When the unit turns off in this manner, all you need to do is hit the on button again, and if you disconnect one part (pants, for example) that would lower the load and the voltage drop would be less, probably below the threshold needed to trip the unit off.

SMSW said:

If you are drawing too much juice while riding, the battery will make up the difference, discharging as it does so. Eventually you will stall the bike. A more likely reason for your problem is a voltage drop to the controller (heat troller) of your heated gear causing it to shut down. My guess is you have either a faulty connection or undersized wires feeding the controller, either from the battery or quartet harness or some other source.

A shut down caused by insufficient voltage is designed into many controllers so the unit shuts off when you turn the bike off - it cannot drain the battery. When the unit turns off in this manner, all you need to do is hit the on button again, and if you disconnect one part (pants, for example) that would lower the load and the voltage drop would be less, probably below the threshold needed to trip the unit off.

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Thank you for the ideas. I use the dual wireless bluetooth controller. The wired piece is in my coat pocket with all 3 connected together.

How many watts are saved by going to LED head lights, tail lights and turn signal bulbs?

drtyrrel said:

How many watts are saved by going to LED head lights, tail lights and turn signal bulbs?

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That depends on what the LED's you choose draw. If you have H4's they draw 110W low and 120W high. The incandecent peanut markers draw 4W each and the brake/turns draw 6W low and 25W on high. So assuming you had high beams, brakes and 4ways on you'd draw a peak total of no more than 252W, so even if the LED's drew zero (which they don't) you'd save less than 252W. I would also assume the LED flasher draws a bit more than the OEM one. Now if you put in load resistors instead of the new flasher that negates the savings as the resistors add in load so the LED's draw the same as incandescent.

My F2 led's supposedly draw about 36W each, so a savings of about 48W. I've only replaced the peanuts with LED's and front turns with switchback LED's so far.
Even before I swapped the front lights I still ran a heated jacket and grips without issues.