The electric capacity of a KZ750e

Hey would anyone know have much extra current I can place on the bike I am getting near the end of this project and I want to add USB heated grips and aux light. 

Can the stator handle this? I am okay at electrics but I dont get how to tell if I will be drawing to much current.

If there are any other threads on this please let me know.I had a quick read but I didnt find to much


Thanks

The only way to know is to try.  Assuming you are not running with the accessories going all the time, you should be okay.  Electrosport makes a stator with 10% extra capacity also, which you can try if you run out of juice.  

I put the below together as a guide, the 750E has an 18amp charging system so not a lot of spare capacity. You might want to consider changing to LED lighting to get some capacity for your "extras"

Nessism wrote:

The only way to know is to try.  Assuming you are not running with the accessories going all the time, you should be okay.  Electrosport makes a stator with 10% extra capacity also, which you can try if you run out of juice.  

Don't know if it would fit (I know some engine parts are interchangeable) but the early ZR7 has a 22Amp alternator which would be approx a 20% upgrade if it's possible (would be a nice upgrade as it hits full output at lower engine revs as well so more efficient all round)

Wookie58 wrote:

Nessism wrote:

The only way to know is to try.  Assuming you are not running with the accessories going all the time, you should be okay.  Electrosport makes a stator with 10% extra capacity also, which you can try if you run out of juice.  

Don't know if it would fit (I know some engine parts are interchangeable) but the early ZR7 has a 22Amp alternator which would be approx a 20% upgrade if it's possible (would be a nice upgrade as it hits full output at lower engine revs as well so more efficient all round)

Ideally, we will have "just enough" generator power without any excess.  Shunt type R/R's are particularly bad about managing excess power, because the stator runs full hot at all times.  That's the nice thing about a series R/R; they reduce heat in the stator by reducing power during low load conditions.  I've learned this hanging out on the GS Suzuki site.  Those bikes burn out stators like crazy, and SH775's are like religion there.  I think it's because the generators make too much power relative to the bikes needs.  In fact, I've heard about guys running KZ stators, because they are lower power.

Nessism wrote:

Wookie58 wrote:

Ideally, we will have "just enough" generator power without any excess.  Shunt type R/R's are particularly bad about managing excess power, because the stator runs full hot at all times.  That's the nice thing about a series R/R; they reduce heat in the stator by reducing power during low load conditions.  I've learned this hanging out on the GS Suzuki site.  Those bikes burn out stators like crazy, and SH775's are like religion there.  I think it's because the generators make too much power relative to the bikes needs.  In fact, I've heard about guys running KZ stators, because they are lower power.

Ed I don't want to be argumentative but I disagree with you on this. Generally manufacturers "size" an alternator 10 - 15% above the "maximum possible load" to do this they create a table similar to the one I posted to calculate maximum load. The generator output is determined by the load put on it by the system (up to it's maximum) therefore "just enough" would continually put the generator under "maximum load". I don't disagree that a "series" or "MOSFET" R/R will prolong the life of the stator but upgraded charging systems are not a problem (as long as the wiring is up to the job and a suitable R/R is being used) however simply banging in a bigger stator with a stock R/R would end badly.
Your statement that the GS units make "too much power" as the output is determined by the load, doesn't make sense (as long as the R/R is in good health) These bikes didn't have an issue with stators back in the day (as far as I can remember) but performance ignitions, coils etc do put additional load on the system. I suspect the stator failure issues are more likely the result of other issues caused by aging, not the cause. Stator windings (just like starter field coils) suffer degradation over time from vibration, insulation " break down" etc which effects their output and makes them work harder (as with a starter when it loses torque and will bench test but won't turn the motor) Bad engine grounding, corroded connectors etc also puts additional load on the stator.
If the "burnout" was caused by excessive output then every time you went on a long daytime ride without the lights etc being on when the system load is approximately 50% of maximum, you would risk stator failure ??

SERIES type R/R's, like the SH775, function differently than the FHXXX units commonly referred to as MOSFET R/R's, which are shunt type.  And GS bikes must certainly burn out stators at an alarming rate, which is not related to age.  The generator makes more power than the bike needs, particularly when the headlamp is turned off.  In fact, Suzuki sends one leg of the stator output up through the hand control for the headlamp switch.  Since USA laws made headlamps "always on" in 1980 (or thereabouts) the feature has gone unused since, even though the wiring is still in the harness.  

I'll find some graphs later showing the difference between a SERIES and SHUNT R/R's impact on heat in the stator....

An electrical engineer on the GS site took these measurements from his GS1100E.  He burned out a stator with an MOSFET R/R, then went on the deep dive into Compufire (series) type R/Rs, to find a solution...


 

Ed I'm not disputing the benefits of "series" R/R's over "shunt" (although the issues are reduced with MOSFET due to the switching speed) my point was that every vehicle on the road for a large part of the time is capable of generating more output than is required at that time to cater for "maximum possible load" and if the R/R and wiring is correctly spec'd this doesn't cause an issue. That being the case if "maximum possible load" is increased with "add-on's" then upgrading the charging system may be required (with suitably matched R/R and wiring) 
I have to say "switching" one of the phases seems like a "cost effective" solution to a design/spec issue.

Hi Guy,
As you know, cars use a field coil alternator, so the power output can be regulated to only what's needed for the vehicle.  Permanent magnet alternators/generators, like our bikes use, produce full power all the time, which is what can damage stator windings and wiring.  

This is a photo of a low mileage cooked (high power) Electrosport stator, after the owner installed a fancy fast switching FH012 R/R.  Theory is that the MOSFET switching is fast to the point of causing more heat in the stator (I can neither confirm or refute this claim, but the claimant is the same EE dude that did the Compufire deep dive).  Bottom line: burning out charging system components are not just a matter of making sure low resistance wiring is used.



 

Ed I get that, the governing factor appears to be the R/R's ability to disperse the excess - I wouldn't be arrogant enough to challenge someone who has delved into the subject far deeper than me