Dynamo and regulator

[bsa-bill]

in a recent post I mentioned my Vreg was inputting 15 volts in to the battery (12 volt) and I thought that was maybe too high, however after a bit of Google it seems 14.5 is OK. (feel free to comment)
I decided to do a more thorough test before spending on another regulator.
Engine running - Pazon electronics - Fully charged battery 12.5 volt, at first the battery began to drop voltage, indicating a regular 0.1 volt drop down to 11.5 then it seemed the regulator came in upping the voltage to 12.1 - 12.2.
First thought was to recheck the dynamo terminals, this is the Lucas one with the flat end plate and two push in rivet things which were not over tight so I wedged them in with  two slivers of card board, good   now to check the dynamo output, previous checks had seen 18 to 20 volts but a bit erratic sometimes showing just 1, it dawned on me I might need to set the scale higher so set it from 20 to 200 v, ah much better steady voltage shown but should it be so high mostly in the 24 to 28 volt range.
when I stopped the engine there could be heard a buzzing whining noise kind of like a motor trying to run, couldn't quite make out where it was from but lifting the regulator the sound changed then stopped ( do they make a noise ) didn't quite sound like it was coming from the regulator but sounds funny it can travel.
Probably need to check the regulator output again in case the dynamo terminals were dodgy the first time - tomorrow
So any answers to the questions raised would be more than helpful.
1. is the dynamo output normal
2. can a regulator handle that much extra voltage
3. should it not input a charge before the voltage drops down to 11.5
4. what is the safe upper voltage it should charge to the battery
PS my meter seems quite accurate when testing voltages, also have SRM dynamo belt drive

[trevinoz]

Hi Bill,
               I assume that you got the high voltage by bridging the output terminals of the generator and running it.
The output will be fairly high with this method and you should keep your revs down so as not to damage the field coil with excess current.
The regulator will not be handling that voltage because as soon as it "sees" the voltage rising above the set point it will wind the excitation of the field coil back to keep the voltage to that setting.
I don't like the regulator not working until the voltage drops to 11.5 but maybe that is a characteristic of your regulator.
!5V is a little high.
The wires which connect to your generator should have split sleeves on the ends which can be expanded to make a nice tight contact.
Maybe a DVR2 would be the answer?


Trev.

[chaterlea25]

Hi Bill

1. is the dynamo output normal?
No
2. can a regulator handle that much extra voltage?
The regulator should sence the dynamo voltage and not let it rise uncontrolled
3. should it not input a charge before the voltage drops down to 11.5?
probably dependant on the regulator charecteristics
4. what is the safe upper voltage it should charge to the battery
14.7v

It sounds as though the regulator was passing power to the dynamo (noise)

Check for any loose or bad connections working from the D dynamo terminal to the reg and up to the ammeter and back to the battery

HTH
John

[morris]

Hi Bill,
regarding the erratic voltage, try an earth wire from the dynamo centre screw to the frame.
I noticed erratic output voltage on my dynamo after converting to belt drive. After connecting an earth wire it showed a steady 14-18V when revved a bit faster than tickover. I didn't rev it more because I was happy with what I saw, but I have the idea it would have gone over 20V if revved hard enough. It seemed that before the conversion it was earthing through the chain.
I also run a V-Reg but can't recall ever hearing it making a noise.
I have the idea the charging voltages you measure are accurate. After a short run I sometimes measure a battery voltage of 11.5V, as when I make longer trips it goes up to 12.5V, but never any higher.

[bsa-bill]

Thanks guys, lot to work on there
Trev - yes two wires joined and the earth is worth a look, I have the split nipple things on the wires will need opened as they are a bit slack.
Morris - I'm in favour of running earth's rather than relying on the frame, hadn't thought of that one though
John - you shame me, I know not why but had assumed that modern solid state regulators got rid of extra volts thermally (obviously thinking PC/electronics), didn't know the Field coil was involved 

should it not input a charge before the voltage drops down to 11.5?
probably dependant on the regulator charecteristics

An after thought - it can only input to the battery what it's got perhaps

This morning I tested the regulator out put again, all connections are now known to be good.
Voltage initially dropped down to 10.7 (this with little throttle) opening it up voltage went into the upper 12 vs further throttle gave a maximum charge of 14.2
Ammeter confirms charges shown, the low initial (drop) in voltage possibly down to not enough revs, it's deceiving in a small shed with Goldie pipes and a fan going, probly sound faster than it is.
So conclusion, I think I'll stick with the vreg and some sort of battery volt indicator for the time being to see just what goes on when out on a run, DVR2 for the future though.
Many thanks to you all for your replies and my gaining some knowledge about the charging system, something I was a bit short of

[duTch]

 Yep, it's fascinating stuff (to we subordinates-well me anyway), I kind've had a kick from playing with my 6V mechanical reg the other week, seeing the cut in points do their stuff when the V got down to (5.?)whatever, and then cut out and adjust them at 7.8 (or whatever),

I guess the electronic ones are same in principle, if not practice...?
 
  Service sheet 804 explains a lot and I found this on the net,
http://www.fromtheframeup.com/uploads/Lucas05_Generator_Output_Control.pdf

 Just in case it's any help to anyone...?

[morris]

Very interesting literature Dutch.
Thanks for posting