In the end its only one RR that is charging the battery through two different circuits. And I am saying this only from experience.I had done this 2 years ago. And the load on the AC line[which was supposed to power the headlight which you are rectifying to charge the battery] is more when charging the battery than when it just powers a bulb.

In short
Stock: Battery coil - normal load Headlight coil - Normal load
Your mod: Battery coil - normal load Headlight coil [rectified and connected to battery] More load than normal.

In short, the mod is unstable as the Bajaj RR quality is not that high to handle such high loads. This mod has failed on mine and prince's bike. This is precisely why I don't recommend this mod.

The fire on my bike was solely because of the faulty Bajaj RR.
The fire could have been fatal.

There should be only one line connected to the battery for charging. From one source only. The one coil one RR for one battery setup is the best one. Highest reliability.

Use Rewinding+APE RR. Although one may need professional help to get this thing done, it is tried and tested by many xBHPians including me.

The APE RR is rock solid and can withstand loads as high as 9 to 10 Amps which translates to roughly 100W of power. There are people running heavier halogens and HIDs[55W] on the ape RR setup.

The mod you mentioned was first carried out successfully by Rahuldevnath. But even his HID didn't last for 4 hours of continuous riding. The charging current is just not enough to run even a 35W HID easily.

Not attacking your post or trying to demean you. Just that I too chose this easier way once and ended up in a near fatal accident.

Hi Prince.. Rahul Devnath.. Abhijeet & All,
I have done rewinding with 19G, connected 1 Output to APE RR & Parallely Stock RR. So that Bike will run on AC as earlier & Battery will get the complete power of Coil. H/L (OSRAM Nightbreaker 60/55) is connected via relay.
Headlamp part is OK, relay is giving power via battery. But rewinding part didn't succeeded, not getting power. Did the winding according to the post by Abhijeet i.e. 75 turns/pole with 19G wire. Can anybody pls help. I cannot remove the stock RR as UGIII requires regulated AC to BCU. Is there any other way so that I can remove stock RR & connect only modified coil with APE RR only. Also help required regarding rewinding coz its not giving power.

Hi, thanks a lot for your valuable input. Of course as mentioned earlier the setup u done was 2 years ago and i just done it now, so let me have a look at it! After all its DIY....anyways its the experience like you that make this forum active! Now to my point, i have done a minor change in the circuit and you may not have noticed it. I added a toggle switch beforehand, so that any misbehavior in the ckt can be switched to defaults. Its a testing phase...now done around 2500kms(over 1 mnth), still didn't showed any -ve effect. Any way ,i will post any problems faced my me for all other Xbhpian's.

UG3's can run full DC. I am running a full DC setup for two and a half years now. The UG3 doesnt necessarily needs a ac+dc setup. The parallel charging and 2 RR idea has been tried by prince and many others too. It has failed in most cases.




Just make sure you keep an eye on the max voltage that is found across the battery terminals at 4k and 6k rpm. Check using multimeter from time to time to see if the RR is healthy. Any sign of overvoltage and replace the RR asap. Faulty RR tends to eat up all the electrical/electronic devices and also result in a fire [which happened in my case]

Also just take a look at KBPC3510. It will make your job easier.