| Author | Message | ||
     Desert_bird |
On the road in north Brazil with my 2008 XB12X. After some troubleshooting it appears that my VR is going south, even faster than I am. Producing just about 13V at the battery at 4K rpm, with constant voltage spikes and dips when out on the road (two greens then into the orange then back to two greens, as seen from my Kuryakyn voltage meter). Been getting progressively worse during constant heat and travel over the last 5 days. Battery keeps getting weak. Stator seems to be strong, and passes all tests - for now. There is new original unit in a store down Sao Paolo (for the equivalent of $370!! That what this stuff costs in Brazil.) Shipping something like this internationally to Brazil reputedly takes up to 4 months. Gets here in 4 days, then sits in customs for eternity. A boat electrician here has suggested just using two VR units for a smaller 12v bike (they run 150-250 cc's here) and joining them together. He is bringing by something tomorrow morning. Can any electricians chime in on whether this possible/ recommended? What should I be looking for? Sure better than 5 days and $370 for a replacement or 4 months. Thanks. DB (Message edited by Desert_bird on October 03, 2011) | ||
| Terrys1980 |
Yes it is possible to wire 2 VRs in parallel to increase the current of which can be regulated. Keep in mind the stock unit is 3 phase 38 amp. Not too sure if the smaller bikes would run a 3 phase stator/vr system. | ||
| Reepicheep |
The connector between the VR and the stator is a common trouble point, so make sure its not just that... I think the 2008's still had the old style connector. You could try putting one single phase VR on each phase. I'm not sure how it will all work out with the bridge rectifier, and with one of the VR's potentially swamping the other(s). It will probably work out, but might immediately smoke a VR. | ||
| Terrys1980 |
To ensure absolute even distribution of current between the VRs, you would need some very low ohm resistors wired in parallel on the output of each VR. Similar to this configuration.  | ||
| Froggy |
Both of you have some inaccurate info. His bike has a single phase 30 amp stator. Another single VR would work, you just have to make sure it is rated to handle at least 30 amps. | ||
| Reepicheep |
That simplifies it. | ||
| Desert_bird |
Sorry that I didn't clairify what Froggy has: 2008 is the newer style single phase 30 Amp unit. Sounds like its possible. I assume that the reason that the guy is suggesting two smaller units (cause they can't get big ones here) is to handle the 30 amps. Prefer to fry a tester VR then something on the bike. Many thanks for the info. Trying it out in an hour or so. Will let you know. S. | ||
| Reepicheep |
Yes, it is for power dissipation. If they are shunt regulators (probably are) then they have to take all the unused power from the bike and throw it away to ground. If your regulator is undersized, it will either fail immediately, or run too hot and fail after a short period of time. My concern about two of them is that one might end up taking all the load, and the other could do nothing, making one fail then the other (instead of them sharing the work). I think that is what Terry's tweak is fixing... if one VR got too much load, the resistors in front of it would make it increase in voltage, which would let the other VR join in the game. I think. Hard to tell for sure when the VR's are black boxes. I have no facts to back it up, but I'd give it better than 50% odds that it would work. I guess you will know shortly.  | ||
| Desert_bird |
Yup. Burnt out a VR with both of them attached and the motor turning at a good rate. Too much juice! Nothing was used to divide the power between them. Could try again, but bills are adding up. Guess I'm ordering that $370 VR from down south. Thanks again for the help. DB | ||
| Sparky |
Perhaps you could try installing a ballast resistor between the stator and VR in order to limit the current output of the stator. The ballast resistor I'm talking about is like the kind used on older cars that have a points ignition.  It is made of nichrome resistance wire with approx 1.2 to 1.8 ohms resistance depending on type and is enclosed in a ceramic fixture. NAPA calls it an Ignition Coil Resistor. If it would be beefy enough to handle the output of the stator though, perhaps the VR you are using would last until you can get the proper parts. |
