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My 9R started having issues keeping up with current draw about a month ago. I tested and found that the system voltage was dropping to 11.5 volts @ 4000 RPM when all my accessories were turned on full blast. In the past, it was always able to keep up. With no extra load, it was able to maintain 14.4 volts.
I tested the output of the charging coils and found them fine. They also had good resistance and no shorts. Since the voltage was OK with little load, I figure the regulator/rectifier would be OK, but decided to test it anyway. It took tremendous effort pull the three phase AC input plug apart on the regulator. When I was finally able to get it apart, this is what I saw:The connections must've become a bit loose and the increased resistance generated heat and melted the two halves of the connector together.
I bypassed the plug temporarily and it works perfectly again. New connectors have been ordered.
Wait - I don't understand - this is for the regulator??
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1994 Yamaha YZ250 CA Street Legal 2-smoke :smoke:
The connector is used to bring the alternator output, which is 20 to 70 volts RMS three phase AC. into the rectifier/regulator. They use three phase AC because once you put it through a bridge rectifier, it's practically DC. After the rectifier, the slightly rippled DC signal goes into a regulator that limits the output voltage to 14.7 volts DC. The battery helps to filter any residual ripple.
This diagram show three phase power before (top graph) and after (bottom graph) it is passed through a bridge (full wave) rectifier:
The magnets on my motorcycle alternator are permanent, unlike a car alternator that uses field coils, hence, there is no way to limit the output as RPMs increase. Therefore, the regulator will turn any unused power into heat and that's why it has big fins.
Last edited by stoinkythepig; 12-05-13 at 09:06 PM.
99 + 02 SV650 ex-race - 91 FJ1200 street - 03 KDX220R woods - 12 WR450F motard/ice
We do a ton of the mosfet reg swaps...they are expensive but no more burnt wires etc....just awsome..
I can't fathom how a MOSFET regulator can affect the current running through those wires. I know they shunt the unused power to ground in a manner that produces less heat locally, but there should be no difference in current flow on the three phase input. The wires don't burn because of the heat produced by the regulator, they burn from constant high current and a slowly degrading connection that produces heat.
The mosfet units don't shunt unused power to ground, they act like a switching powersupply, connecting and disconnecting power legs at a very high frequency as needed to satisfy the current demands at any given moment. Low draw, your stator spends more time 'unplugged'. High draw, keep the connections up with a longer duty cycle. The wiring only sees actual demand as a result instead of the full output of the stator at all times.
I don't think you can use a switching regulator in a permanent magnet alternator application because stator coils will generate too much voltage and the insulation will eventually break down in them when they are not allowed to flow current. I'm pretty sure that the MOSFET regulator still just shunts the unused current to ground like an OEM regulator. They just have less internal resistance than the SCRs that they replace, so they don't get as hot. I could be wrong though.
I raced for a season with my stator unplugged, no signs of degradation. There are racer targeted regulators now that are even more aggressive about disconnecting to keep your stator setup from sapping HP.
I was thinking the insulation breakdown would be over a fairly long period of time, not instant and not after just one season of racing (thinking that's probably less than 1000 miles).
I looked around for notorcycle MOSFET switching voltage regulators and cannot find any for sale. Do you have a link to one?
MOSFET is an extremely common upgrade, from what I've read.
http://www.roadstercycle.com/
Although the latest interwebz wisdom suggests that a "series" regulator is even better.
http://www.roadstercycle.com/Roadste...Regulators.htm
I'm 90% certain Shindengen MOSFET regulators are shunt type, not switching.
Then I have no idea what you are looking for. Maybe the 'series' type. I have not read enough to know what type of IC it uses.