Over-charging? Reg/Rec Mod

[2XSive]

So with the recent restore on my TX650 I did the reg/rec mod as outlined by 5Twins in the "DIY Reg/Rec. 5twins and Jim thread". I've done this mod to several bikes now. Was running the original rotor and it was charging good hitting 14.8v on higher revs. I knew it was a matter of time before that 50 year old rotor blew, so today I installed a fresh rewind that I bought from Jim back when I first got the bike running 3 years ago (when I did the reg/rec mod). Voltage is now hitting 15.25 and seems to stay at that voltage or slightly lower above 3,000 RPMs. I'm also running this little lithium battery with on-board battery management system that protects against over and under charging. Really impressed with this $69 little battery and its cranking ability. Is it incompatibility with the VR regulator and the lithium battery, or is the VR reg not doing its proper job, or is 15.25v okay, given the "smart" battery involved?

 

[Jim]

I don't know enough about that battery to say one way or the other. About all I can suggest is sub in a lead acid or AGM battery and see if it's still overcharging.
I tend to think the regulator is overcharging, but as I said, not real versed on that battery.

 

[2XSive]

Swapped in a good AGM battery. Same results. 15.29volts charging at 3,000 RPMs. Looks like that VR is bad even though it was brand new when I installed it.

 

[2XSive]

Just wondering....is anyone aware of a B-type regulator that regulates better for lithium-type batteries? I see Rick's has a B-type here, but it is both a reg/rec, and at $130 was hoping for a better alternative that has just the regulator for this conversion on my 73.

 

[5twins]

I've tried several VR115's and their equivalents (NAPA VR1010) and it seems their max output voltage was set slightly different on each one. But, they all fell in the 14.2-14.5v range.

 

[2XSive]

Thanks 5twins! I ordered another VR115. Meanwhile I installed the original mechanical reg and it is holding voltage to 14.45v. Will keep an eye on it and tune it down as needed. I am guessing the VR115 I installed may have been used even though it was marked as new. The box had been opened and it was clear from a couple of scratches that it wasn't new.