How much can the charging system handle?

[ST Nut]

My first post, love the site and my 03 ST. I am looking to add some stuff. I want heated seat (corbin already installed) chatter box, cruise control, and 12v outlet (which one to get?) Will the stock charging system handle all of this?

Thanks,
Jeremiah

[Ken]

I seem to recall it puts out over 400 volts?

[Tor]

I seem to recall it puts out over 400 volts?
Ouch,,,,,that's gotta hurt:D

Around 700-750 Watts at 13.8V or close at 5000 RPM. I've never measured the pull with engine running, with front lights and rear lights running, i.e. normal operating conditions, but I would estimate around 110-130 watts, 150 at the most.

[Tor]

230W for lights???:eek: ??? You must be running 100W bulbs in the nose. Mine is a non-ABS. :D Agree,,I should have included it. In other words, you can add more farkles on a non ABS than on a ABS bike....Tell you what, I'm gonna measure that thing with a meter, and settle this. :)

[Ken]

You're right. Norman posted on this subject some time ago and said, "Actually the specs say 740W at 5000rpm. Bike bike is typically quated as having a 660W alternator. I have speculated that the 660 figure is what you get at typical highway speeds. 5000 in 5th is really moving."

[Blrfl]

I've posted a copy of the spreadsheet I used to estimate what's available on a 1300 for electrical farkles in the ElectricalReference (http://stwiki.notonthe.net/twiki/bin/view/ST13/ElectricalReference) topic on STWiki (http://stwiki.notonthe.net/twiki/bin/view/ST13/WebHome). There are some notes about what's included in the estimate and what was left out. My estimates for the radiator fans and fuel pumps could be turned into real numbers if someone has their bike apart and can measure the resistance on each.

I did put in one bullet about the ABS that is probably worth discussing here:

Whether or not sufficient headroom should be left for the ABS modulators is an issue of some contention. When in use, they are believed to draw a combined 40A (480W). Actuating the ABS would exceed the spreadsheet's calculated 21A of excess capacity under normal running load, so it is quite possible that the system was designed to draw current from the battery. It is unlikely that the alternator's full capacity would be available during emergency braking, as the rider would likely be off the throttle and the engine would be turning at less than 5,000 RPM.

--Mark

[ST Nut]

Well, I just came from a VFR800 and the high beams on at idle could cause charging issues. Sound like I will be safe. My bike is not going to be anything crazy, just trying to keep up with my buddies BMW :) Which 12v adapter would you recommend. I like the idea of a regular car 12v plug for more options, but my main use is for my heated jacket.

[kkahlm]

I just installed the powerlet plugs. Installation was a snap. Although I don't think they are as common as SAE and Cigerette type plugs, many products come with this type of plug since BMW uses them as well.

You can always get one of the myriad of adapter plugs that are on the market but in each adapter there lies the hidden threat of disconnection or high resistance.

Just my $.02

[CruisingDog]

I just installed the powerlet plugs. Installation was a snap. Although I don't think they are as common as SAE and Cigerette type plugs, many products come with this type of plug since BMW uses them as well.

You can always get one of the myriad of adapter plugs that are on the market but in each adapter there lies the hidden threat of disconnection or high resistance.

Just my $.02

Just did my Powerlet dual socket 'under seat' install also. Didn't think much of their adapter to a cigar socket thingy [it plugs into the powerlet socket]. They don't have anything to latch the cigar plug in place and can quite easily fall out whilst you're riding. You'd be better off ordering a powerlet plug and going to Radio Shack and getting a cigar adapter and then butchering it to make something reliable.

[CruisingDog]

Nope, fact!. :)

If you look at the duty cycle of the flashers they are on for half the time. 50/50 duty cycle typically. Integrate this over time and in this case, the average is half. Bulbs are rated by their "on" power. If they are on for half the time [over all time], you use half the power. Simple.

Do you use power in your house when your lights/appliances are turned off ? Nope! Only when they are turned on.

As a matter of fact, this is how most energy saving devices work (and dimmers for that matter). They change the amount of time that the bulb is actually on for and since your eyes don't see high frequencies (above 70Hz), it looks like a continuous source of light. What's actually happening is that your eyes are "averaging" the light out. To be more accurate, your eyes are integrating over time.

This technique is called Pulse-Width Modulation or PWM for short.

Now you know!

[CruisingDog]

Leo, you beat me to it. I was just about to post the question,

Is the charging system specified as peak power or average power ?

Typically a charging system is specified as average power since this is "heating" power and that is what a PSU has to dissipate before thermal shutdown/meltdown. Peak power can be considerably larger, depending on the design.

I don't know what the spec says about peak/average so my comment's may have been premature.

[Blrfl]

And God help ya if, during all of that, you're also trying to get the engine restarted. :D

I'm sure all of the wiring is designed to hande peak loads, but realistically, the battery has to act as a current source under those conditions. There's no way the 62A the alternator has available could supply the bike's usual needs plus an additional 40A when both ABS modulators are in use.

I have a clamp meter at work that will plot current over time. Next time I have the right side apart, I'll have to borrow it and see if there's room to leave it attached to one of the battery cables during a short ride. I suppose that if the charging system could be safely disabled, I could also get a real-world measurement of how much current the bike draws. Hmmm...

--Mark

[Burger]

Just thought the following might be interesting info for this thread...

Calsci (http://motorcycleinfo.calsci.com/ST1300_c.html)

Regards,

[Burger]

I don't understand that statement but then I'm only working on what I've believed for quite a few years and don't have anything scientific to back it up with.

In the days of dynamos I would have agreed with you, but alternators are designed to deliver constant current and power across a wide rev range. Certainly they won't do this at tick over which is easily demonstrated by dimming headlamps as revs drop, but from about 2000 rpm, a well built alternator and regulator should be delivering very near to its maximum capability.

Regards,

[jgilmore]

I have a datel volt meter installed, and it doesn't matter much what I have on, including a garmin 2610, high beams, motolights, Starcom, cooling fan running, four-ways blinking and FIAMM horns blazing all at the same time. I don't believe I have ever seen any more than 3 or 4 tenths of a volt drop with the engine running anywhere above idle, and maybe .6 volts at idle, even with all of these things on. It hasn't been cold enough to plug in my Gerbing gloves and jacket liner, I am interested in seeing what affect if any that has (even though adding up the "extra" wattages is below what the calsci site says you can have). But I don't think I am anywhere close to pushing it. It is still charging, I don't believe I've ever seen it drop below 13.5 or 13.6 volts even at idle, and whenever it drops that low, it is usually momentary. I think if I were close to overloading, I would have a bigger drop than 2 or 3 tenths of a volt. I will probably bust out the gerbings next week or so, I can crank everything up and get a reading. I put the datel on just to keep an eye on things.

Now the generator on my XR650R is a different story.....

-John