TOPIC:

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This?

 

Yes
 

Thank you. Carry on!

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This is why I love KZR so much. Incredible depth of knowledge and the enthusiasm to share it.

I will definitely weigh my options, but at the moment, all things considered, I am leaning towards picking up a used genuine Kaw reg/rec from a Ninja 500 as suggested by loudhvx. Principally because I suspect that even with an 'improved' charging system, that between the Dyna and some uprated lighting, the bike may yet be using most of the voltage supplied, leaving little gain to be had sparing the stator the extra work when the whole system is fully charged and idle... 

That said, thanks Nessism for the link. The price on a used unit isn't a whole lot more than a used shunt type.... I had only investigated new (genuine?) ones to date, and they were in the $100 USD neighbourhood, which is getting spendy.

So, as always it seems it's a matter of what you are trying to achieve and willing to spend. I'm pretty curious about the specifics of how the SH775 is built and how much voltage drop there is at maximum demand..... I would hope that for the money, it might come close to the alternatives, but definitely do not have a scope at my disposal to look at the differences. On the topic of the Shindengen unit, I assume that spade connectors will suffice? I'd happily shell out a few dollars for a harness, but failing that....it's connectors and crimping.

The SH775 is a "SERIES" R/R which means is helps protect your stator from shunted current return to the stator which causes heat build up and thus damage.  It's a superior technology.  

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The SH775 is a "SERIES" R/R which means is helps protect your stator from shunted current return to the stator which causes heat build up and thus damage.  It's a superior technology.  

 

It's not that simple.  Shunt type R/Rs of this vintage utilize Thyristors to 'shunt' the current but Thyristors are uni-directional so they only 'conduct' in one direction when turned on (think diode) so power is shunted for only half the voltage cycle in any given phase.  In other words, when the alternator is outputting max power to the load (without shunting) there's actually more power/heat in the stator than when it's being shunted (since shunting 'halves' the power output).  The shunt type of RR is a very elegant design;  as  loudhvx points out, they deliver a higher maximum power to the load compared to a similar series design.

A Series type with modern, or more exotic, low voltage, high current components may be a very good choice, but the drawbacks of the older Shunt design are overstated IMHO.
 

I'm NOT an electrical system expert but I've read a LOT of info about the problems with motorcycle charging systems like ours.

Permanent magnet charging systems like our KZ's use don't adjust output based on demand.  They pretty much output power based on rpm until a saturation level is reached, somewhere in the range of 4500 rpm or so.  When using a shunt type R/R any power that the bikes systems don't use is returned to the stator where it's dissipated in the form of heat.  

The stock KZ charging system doesn't seem to have much in the way of reserve power so shunting the excess power to the stator doesn't seem to have as profound an impact on the system compared to some other bikes, such as Suzuki GS's.  Those bikes burn up stators with regularity.

A SERIES R/R eliminates the return current into the stator, and the heat that produces.

I can't speak to an effiiciency comparison of a shunt vs. series R/R, but I do know that if your charging system is even half way up to snuff a SH775 won't hurt it.  And when comparing the benefits of series vs. shunt, it makes very little sense to go shunt in this modern age.

Shunting vs series is pretty complicated.  A shunt event does instantly alter what the stator sees as load impedance.  And at first glance it would seem the current would run up to catastrophic levels immediately.  But because the stator is made of inductors, the current cannot jump instantly to meet the demands of that impedance drop in the load.  This limits the power dissipation increase within the stator itself.  So in a way, the stator output, or more importantly, the total power produced by the stator, and thus ultimately dissipated within the stator, is altered during a shunt event, and is lower than what would be expected under a true, long-term short-circuited output. This would happen more so at higher RPMs, which is right when the shunting would occur most, so is when it's most needed.  All of this acts as self-protection in the stator from shunting.  The overall power dissipation does increase within the stator during a shunt, but does not increase catastrophically as one might expect when you short the output. 

Anyone familiar with old tube amplifiers for guitars knows that often the output-jack of the amplifier is wired so it short-circuits the output-transformer's output wires when the speaker plug is removed from the output-jack.  This is done for a similar reason.  The inductance of the transformer helps to protect it from damage over short periods.  In the case of the guitar amp, for reasons not related to our charging systems, if the jack were to be left open with no speaker connected, and the amp is trying to make sound, the output transformer is often damaged, almost instantly, to the dismay of the guitarist. So a dead-short is used to provide a short-term protection.  The idea is that the guitarist will stop trying to play guitar as soon as he realizes the amp is silent.

I suspect Kawasaki worked long and hard to get such a good match between the permanent-magnet alternator and the power demands of the bike.  If they had not, we would have seen far more failures of charging systems with shunt regulators. Apparently Suzuki did not quite get such a good match.

 

A SH775 can be had for about $50.  At that price point why go shunt?  

And GS Suzuki's are not the only bikes that burn up stators.  Do a google search and you will find that tons of other bikes are making the switch to series type R/R's.  There is no downside, and the upside is worth the effort to make the conversion.

Well, not to be a cheap ass, though I'm sure I am, but $5 beats $50 for me.  $50 is still a really good deal.

 

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There is no downside, and the upside is worth the effort to make the conversion.
 

I can think of a couple of downsides: 

First: As a series R/R's components are 'in line', the effective power to the load is reduced (this may be trivial in practice).

Second: With a shunt design R/R, the active components are only active when shunting excess power.  In a series system the components are active all the time that power is needed so for similar system a series R/R may very well run hotter.

Neither of these are necessarily deal breakers and if I was in the market for a new RR I would definitely consider them.  However, I still think there's nothing terribly wrong with the older shunt designs which have worked faultlessly for decades.

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 However, I still think there's nothing terribly wrong with the older shunt designs which have worked faultlessly for decades.

Kawasaki seemed to do a good job of balancing the generator output against the required demand, thus there isn't a whole lot of excess power which gets shunted back to the stator.  For that reason KZ stators live longer than those in many other model bikes.  Given that, a shunt type R/R isn't the worst thing you can do.  If buying a new high power stator, or if changing your R/R, I'd upgrade though.  It's not that the R/R is going to fail, but they will put your stator under more load than would be the case when using a series type R/R.

Been a little bit, but I started the thread, so I think it's a little hard to be accused of thread jacking.

Not going to wade back in to the technological arguments which I think were really quite well laid out above. However, I will say this, that if you happen to be in Canada, and aren't lucky enough to find one used, or off a scrapped ATV, etc... there is something to be said for the cost advantage of the older style (Ninja 500 as mentioned above) style of reg/rec.

While it was suggested that the SH775's are reasonably inexpensive via Ebay, and that is reasonably true, I just figured I would throw out that since Ebay has switched to the 'mandatory' international postage and customs payment system, rather than letting your make a deal with the seller and take your chance on cheap shipping, buying across the border is not such a deal any longer.

It was going to end up being something in the neighbourhood of $80 CAD for a used 775, where the older units seem to be available for ~$15-20 locally (SH530). Not necassarily a deal breaker in any case, but then you might want to figure in the 10USD +shipping for the Triumph harness, or the DIY materials, etc...

Not saying this should dissuade anyone from ponying up for the 775, just figured in the interest filling in some details on the current price difference, I'd mention it. I think without real world, controlled testing it would be pretty hard to prove that shunt reg/rec is going to destoy your shiny new stator considering how well the OE units have been doing (including mine) for years. Equally, you may decide it's worth the extra spend to add some insurance against damaging said new stator. At the moment, it is something like $100 for a new high output 3-phase stator from my parts dealer.

This will be a problem for next year for me anyway. Bike rides well enough for the rest of our season, and I doubt I will have time to install new lighting this year anyway. So, I'll have all winter to try and score a deal. Winner will probably be what I can get cheaply and locally, or at least on the Canadian side anyway.