another dynamo - DVR2 question

[mikeb]

I rebuilt the E3L a year or two back (armature, brushes, bearings) and the system charged fine for at least a year.
recently charging has been intermittent. its setup 12v neg earth, new AGM battery. I've re-checked the wiring for faults (including those dreaded bullet connectors into the E3L). the battery, DV2 and dynamo all have wired earth connections between them so not just relying on the frame.
testing:

• with D+F joined together, when running, the dynamo will make a bulb glow with volts >15 at revs.
• I've tested the DVR2 according to their test sheet: https://dynamoregulators.com/documents/DVR2-user-test.pdf
  as volts on 'D' rise, the 'F' volts switch off about 14.2 volts so that looks OK. I assume switching off the field is its method of operation. The output volts keep rising on the bench test as 'D' volts increase - is that right? Question 1: Should that happen?
• on the bike with no battery, the DVR2 out will rise with revs then hold at 14.2-ish volts.
• with the battery connected the DVR2-battery never rises above the voltage of the battery - currently about 11.8v. Hence no charge

So - i assume the dynamo is not delivering the power necessary to charge the battery. I noted one brush has worn unevenly so could be the culprit. Or some other dynamo fault?
Or - less likely - there's something weird about the DVR2

any suggestions?

thanks

[groily]

• on the bike with no battery, the DVR2 out will rise with revs then hold at 14.2-ish volts.
• with the battery connected the DVR2-battery never rises above the voltage of the battery - currently about 11.8v. Hence no charge

Quick preliminary Qs -

Does the DVR2 output hold up at that regulated load-free 14v-odd, with the LIGHTS ON, engine running at moderate rpm and battery removed? Good if it does as it shows the system can support loads  . . . not so good if it doesn't  . . . a dodgy brush or similar could account for that  . . .

What is your ammeter now saying about current when the battery is in circuit? With and without loads applied? You said 'intermittent' charge in the recent past, is that now 'gone AWOL' totally?) And,

Have you tried charging the battery independently to get it back to full charge? To see if it accepts it from a charger?

Obviously summt not right, let's hope it's not an armature fault after all your efforts  . . .

[Greybeard]

Chain or belt on the dynamo?

[mikeb]

good questions!

• intermittent charging in that some days appeared to charge (amps showing and the fancy voltmeter on the bike >14v) and more recently mostly not. its been in decline.
• the battery is only a few weeks old and was recently charged with a charger - it did accept the charge. the previous battery was very dead.
• ammeter is saying nothing - as in no charge showing. the ammeter does work.
• good idea to test with no battery and lights/load - I'll need to do that in the morning. the bike is on LEDs atm so i may have find an old incandescent bulb for a better test.
• and - belt or chain GB? well, ah-hem, gear driven actually  (clue in my footer) - its definitely spinning
I'll report back in the morning. I was supposed to be going on a track day on the modern but cancelled due to expected torrential rain. so more time to fix BSAs.

cheers!

[groily]

It's a good point about spinning. But if you have run it with the brush end cover off under load, you'll know if it is.  It's a PITA with a magdyno if the clutch is slipping or the fibre gear part-strips, that's for sure!

Think you're right in needing a decent wattage bulb or other load, not a good test with just the amp or two needed for tail and LED.

Although the ammeter seems to work, might also be half an idea to bridge the 2 terminal posts or hook both sides to same one, to ensure a good link from reg to batt / switch, and then see if lights brighten with rpm or batt voltage rises . . . (just to eliminate one thing from the equation).

May the rain stop!

[Greybeard]

belt or chain GB? well, ah-hem, gear driven actually  (clue in my footer) - its definitely spinning

When my belt went bad recently the dynamo was still spinning, just not very much.

As you mention gear driven I presume you are asking about your B33

[KiwiGF]

Hi Mike, I would suspect the brushes and/or dirty commutator, I am pretty (but not 100%) sure the dvr2 needs to see a voltage on “D” before it will start giving power to the field coil. This voltage results from “residual magnetism” in the field core when the engine is running. If there is no residual magnetism, or it is the wrong polarity, or the brushes have enough resistance the dvr2 won’t start giving power to the field coil, hence no charging.

It was many years ago but I had a similar issue where I would go about 400 miles and charging would stop, cleaning the commutator fixed this but the issue would return, new brushes fixed the issue more permanently, I assume the old ones were soft, and made the commutator get dirty.

I found the problem by running the bike with D+F connected when it was in the not charging state, it did not “self generate” and power a bulb,  but briefly applying a voltage to two connected wires started it generating, and it kept generating, so the issue was it did not “self start” from residual magnetism.

Your bike does “self start” by the sound of it, but maybe it is not doing that consistently?

There must be a test you could do whilst the dvr2 is connected, to emulate a “self start” eg apply a voltage to the field coil or armature, but not damage the dvr2.

[mikeb]

bit of an update.
driving the 'D' with a variable power supply, the DVR2 can supply 5A at >=14.4v into a load, while switching the 'F' on and off about 14.3v. So that works fine, and the bikes wiring and ammeter etc check out fine with minimal voltage drop (resistance) with current.
So its the dynamo. on closer inspection maybe 3 things:

• the brushes - easy remedy
• it appears the small bearing at the commutator end is turning in the housing. hmmm. any ideas on how to secure that? I half recall using some bearing retainer when i installed it, so that didn't work
• its possible the clutch is slipping. yes GB, its a M01L on the B. so I may need to strip that down and have a look

thanks for all your suggestions / guidance!

[groily]

Sounds good mikeb. 5A at 14+v = loadsawatts.
So yup, could be the brush you mentioned or any of the simple things that'll be obvious when you poke about.

On the loose bearing, I think some heavier duty bearing fit is probably your best first bet, as the monkey metal isn't very proof against radical remedies like trying to machine out & replace the steel insert. ( I'm sure some folk have done it, but those brush end parts are fragile at best of times.)
One other thought, though - is it possible you could get a 360° wrap of self-adhesive stainless steel shim tape round the outer race and persuade it in? Maybe if you eased out the steel insert very gently? Down at, say, 0.03mm and 0.05mm thickness, that tape can be a godsend for light duty.

If the clutch is slipping, that is boring!

Good luck!

[trevinoz]

I have secured many of those bearings with Loctite.
I Loctite the drive end bearing as a matter of course.

[mikeb]

Trev - it might depend on the clearance, but what flavour loctite would you favour? i have some 641 on the shelf (medium strength / .2mm / 150 deg C) but i think that's the one that failed already (or my application of it).

[trevinoz]

Mike,
I think that it is 609 which is a bit stronger than641.
I have used 641 with no problems.
If there is a bit of a bend in your shaft you will find that the bearing oscillates slightly.
Loctite can stop this but it is not a very elegant engineering solution. I guess that this will shorten the bearing life but mostly these bikes don't get a lot of use compared to when new so just another thing to watch.

[mikeb]

turns out the MO1 clutch was loose so now the nut tightened to 7ft-lbs. i bought this magdyno a few years back with proper money from a 'well-regarded' reconditioner who appears to have not peened over the tabs on the lock washer behind the pressure spring. grrr. so there was I doubting and testing the DVR2 when it was something as dumb as that. the dyno did spin GB but now I assume not so much when under load.

next and hopefully last question: where and what actually locates the smaller bearing on the E3L armature shaft at the commutator end, or does it not matter? the pic below shows where the sealed bearing would align on the shaft between the spacer and the end screw. there is no stepped washer or thick felt (gone with the open bearing?). So the bearing looks like it could move on the armature shaft between the spacer and end screw/washer. I assume if there was felt and a washer then the bearing would sit slightly off the end of the shaft, and be positively retained by the screw.
do i care? does anyone bother to make up a new stepped washer? am i overthinking this again?

thanks!

[trevinoz]

Either make a new spacer or put a washer under the existing one.

[mikeb]

so Trev how far off the end of the shaft should the outer of the bearing sit. 1/16" or more?
cheers