Voltage Regulator

[BPT]

I was going to change mine, looking for the ones with higher output.  I know that Rick sells the Hella version (and seems that's the only place to find that one?). I see that Motobins has one as well, might be a BMW version? Didn't find any specs (waiting on a reply from them for details) on theirs.
I know that there are some fans of the Hella from Rick. Anyone know of any different, better, etc.? Any experience with the one from Motobins? That one would be more expensive.

              Thanks

[Barry]

High set point voltage regulators tend to be more expensive with no real justification as all they do is substitute different value components.

I have a mechanical VR which can be adjusted so no specific recommendation.

2 points though to consider:

Any VR with 3 terminals will work or even a 2 terminal one as D- is earthed.

There are ways of fooling a standard VR into charging at a higher voltage by substituting a zenner diode or losing a fraction of a volt across a diode. See Snowbum for details.

http://bmwmotorcycletech.info/Wehrle.htm

[misterpepper]

Amazon sells an adjustable one by LActrical (link) that appears to be the same one sold by other aftermarket sites pretty cheap. I just installed one and can confirm that it works well as a regulator, but I've only had it installed for a few miles, and then my transmission blew up. Related?!? I wasn't able to open up my regulator to see if it could be adjusted or add a diode, and I wanted to charge at a higher voltage because my Lithium battery wasn't getting enough voltage to stay charged. Initial tests were good and I was able to adjust it to charge at 14V at the battery when cold. I pretty much had to max out the adjustment to get that, but I was only getting I think 12.8V before, so something may be wrong elsewhere. I haven't tested it hot yet to see what voltage I'm getting at the battery.

[Barry]

I wanted to charge at a higher voltage because my Lithium battery wasn't getting enough voltage to stay charged. Initial tests were good and I was able to adjust it to charge at 14V at the battery when cold. I pretty much had to max out the adjustment to get that, but I was only getting I think 12.8V before, so something may be wrong elsewhere. I haven't tested it hot yet to see what voltage I'm getting at the battery.

Was the battery absolutely fully charged when you took these readings ?  If it was then 12.8 volts surely indicates a faulty VR. If not then the voltage is dragged down a little by the charge current into the battery.   When I was playing with mine I found it very instructive to tape a digital voltmeter to the tank and ride around while observing the charge voltage. You may find it will keep on rising up to 4000 RPM.  The voltage at the end of the ride was what I was looking for because by that time the battery will have recovered full charge and any negative temperature coefficient built into the VR will have taken effect. 

I ended up with 14.5 volts cold and 14.3 volts hot. What you are looking for from a battery safety point of view is what is the maximum voltage when the alternator is under minimum load. You can play with that idea if for example you always ride with lights on or any other load but be aware the voltage will rise if that load is removed

[misterpepper]

That's a great suggestion. I need to watch for a Harbor Freight free multimeter coupon. I just tested at idle and off idle to about 4k rpm in my garage. Most I got to was 14V, and figuring cold was worst case buttoned it back up and called it good for the time being. Battery was probably 60% or so.

[Bob_Roller]

I bought a high voltage regulator from Rick Jones, originally put it in my '81 R65,saw at best .4 volt increase at 5000 rpm, to 13.8 volts .

I put my Guzzi on the road about the same time, it has the same Bosch charging system that airhead BMW's have .

I had a lot of electrical issues to get sorted out, under voltage from the charging system was one of them .

When I finally got everything sorted out, I put the Hella higher voltage regulator in the Guzzi .

I rewired  parts of the system with larger gauge wire and had to out in two separate switches for the head light, switch was broke and no replacement available .

With only the ignition system being powered , possibly charging the battery, I can get 14.2 volts at 5,000 rpm .

I think the 36 year old components in my '81 are showing signs of degradation, I put PIAA 40 6 inch, 14 cm driving lights on the crash bars, so they put another 110 watt demand on the charging system .

With full electrical load at 5,000 rpm, my charging voltage is around 12.5 volts with the higher voltage regulator .

If I were to do this again, I'd get an adjustable regulator .

http://www.euromotoelectrics.com/product-p/vr-extadj.htm

Here's a link to Snowbum's BMW technical site, it has a procedure to increase the voltage of a stock OEM Wehrle metal can type voltage regulator .

http://bmwmotorcycletech.info/boschelreg.htm

Don't know of anyone trying this procedure !!

[BPT]

Bob - your comment about the old components was why I was thinking of replacing mine. I wasn't sure if it was worth it to try and mess with it.

I'd originally thought about getting an adjustable one. But then realized I'd probably just be adjusting it to get what the higher output ones do, right?  So that's when I figured it best to just get one of the higher output versions to begin with (and also after I heard about the process of getting the adjustable set up).

I'm having frustrating charging problems and not sure that a new regulator will solve everything but I need more oomph there anyway.

[mrclubike]

I did the adjustment procedure to the original reg  that Snow talks about
But just found it still to lazy meaning the voltage  would drop to much in relation to the load or rise to much with loss of load
It just may have been that the reg was just getting old

I never tried one of the "high output regs" (higher voltage reg)   they may be more stable

Of course the charging voltage will be  dependent on the battery state of charge so the battery needs to be fully charged after starting and everything turned off that normally can be except for the  ignition   in order to properly adjust the reg to its max voltage 

[BPT]

Here is what Motobins sent regarding the BMW regulator they offer:
Yes this is a BMW item supplied by Wehrle and has the BMW logo stamped on
it.  On the unit it say 1 244 737.2  , Wehrle , 55 990 006 , 14v / 2

This is all the info we have. 

[BPT]

So Bob Roller (and anyone else, really) - you said if you were going to do it again, you'd go adjustable. Why would you go that route?  Not knocking your choice, just wondering about the advantages.
As I mentioned above, I thought about that but then realized I'd just be trying to adjust it to what the others are already set for, right? But I'm sure I'm missing something.......

[Barry]

you said if you were going to do it again, you'd go adjustable. Why would you go that route?

Because it would allow for adjustment to suite different battery technologies. I've already adjusted mine twice first for a standard Varta wet cell and then for AGM/Gel hybrid.  Even among one battery type the manufacturer may recommend different charge voltages e.g. Odyssey likes a higher voltage than some other AGM's. Then there is lithium ion etc. 

As a technological aside modern cars have given control of the charging voltage to the ECU such that they do much of the charging on the over run at 14.6 volts in a simple form of regenerative braking.  We are Eons away from that with an Airhead but optimising the charging voltage to suite the battery does make the best of the generating capacity available.

[BPT]

Thanks Barry, I figured it would be something like that.
I'm still thinking that, for my purposes, the simple, non-adj. route is probably fine.

[Bob_Roller]

BPT, what are your symptoms with your charging system ??

[BPT]

Oh my, not sure where to start. Not to sound like a smart ass but it just doesn't seem to charge.
When I bought it I was keeping close to home getting used to it and kept ending up dying everywhere.  I finally took the battery to get tested and they told me it was bad (bad cell). I called where I'd gotten it from and they offered to replace the battery (strangely, their load tester didn't find a problem with the old one?).
I was hoping that was the problem and was going to make it a point to do more long stretches on the highway.
Unfortunately, the problem has continued.  If I put it on the battery tender overnight, it'll usually start right up. But I never know how many starts I'll get.
I've done some basic things - a couple of months ago I cleaned up contacts and connections, I've got mostly LED bulbs now, I try to keep the battery on the tender if it's going to sit.
A few days ago I had this battery checked and it showed good but it doesn't seem to want to stay charged.  I took it off the bike and have it sitting in the house, put it on an old school charger and it's holding at about 12.50 -55.
Although I know it's simple, I'm new to BMW's and, of course, the charging system.
And I generally find this sort of thing frustrating (electrical mysteries).
I've been out of the country since October but now that I'm back, I need to tackle this. I am looking through stuff to try and find a step by step checklist to try and diagnose.
I was going to attempt that before asking here but since you asked.........

[Bob_Roller]

Does the red 'GEN' light come on when you turn the key to the on position ??