Battery dieing early

[groily]

Summat not right Musky. I'd be more guided by the ammeter than the digi-meter in this case - because ammeters don't lie usually and those readings are far too high if they're as before as in 4A with lights on, 8A with no lights. Some meters aren't great, as peeps are saying.

I have just done an identical test. Same standard E3L, DVR2 at 12v, with a Motoblatt 16.5 Ah battery, well charged like yours Musky. So pretty much what you have, including battery size. Using my RS Pro digi-meter, see pic. (Which is a good one, but not exceptional I don't think.)

I don't have enough hands to take pix of bike running with meter in one hand, throttle in t'other and  camera in non-existent third - But what I get is not at all what you get!

A rock steady 14.2 or 14.3 v at all revs over about 2500 up to about 5000 (no tacho on old 500 AMC twin!), with a 1A charge, lights off, from somewhere around 1750-2000. Battery base voltage was 12.9v this cool morning.

I think you should try swapping DVRs, or maybe (EDIT No, definitely!) first check there isn't something at the dynamo causing a short between D and F, causing the regulator to be overridden. It's job is to make and break that connection to manage the current fed into the field. I'd say your field is being over-fertilised!

[muskrat]

G'day Bill.
Thanks mate.
Bugga the DVR on the Cafe is neg earth, on the A7 is pos earth. 
Suppose it's not a big job to convert to neg earth.
Cheers

[KiwiGF]

G'day Bill.
Thanks mate.
Bugga the DVR on the Cafe is neg earth, on the A7 is pos earth. 
Suppose it's not a big job to convert to neg earth.
Cheers

My digital voltmeter gives inaccurate readings when its battery needs replacement, just a thought.

On my B44 the reg (zener diode) limits charging voltage to 15v, which I think is only slightly high for modern batteries.

I had two DVR2 fail early with 12v on my B31 and reverted it back to 6v, like my A10. No probs since.

[groily]

Suppose it's not a big job to convert to neg earth.
Cheers

Nah, 2 min job for this purpose Musky - as long as the 'tronic sparks are OK with either polarity?. Just need to flash the field of the dyn, wouldn't worry about reversing the ammeter connections unless staying neg forever ( + will show as - and vice versa).

But seriously, I'd check for a fault at the dyn, because if there is an unwanted short between D and F it would explain the high charge rate even with a big and well charged battery and would explain maybe why the old small battery got fubarred. The symptoms would persist whatever regulator was used. If this is the problem, the dynamo will self destruct at some point for being run unregulated (especially at your sort of rpm!!), so I'd be a bit cautious.

If the dyn has a bakelite end cover, I'd pull it and make 100% sure the tags on the rear of F and D terminals weren't touching (it can happen!), and that the wires into the F and D sockets hadn't got a stray strand bridging them, or if the wires are sheathed off the dyn, that there isn't something amiss under the sheath. Similar check on dyns with tin ends, but the problem is less likely to be on the inside owing to the space between sockets, unless the D brush tail is squashed against the F lead or whatever.

Unwanted continuity  - with the F and D wires disconnected from the dyn - can be picked up using a meter, but there will always be a low resistance there because F is connected to Earth through the field coil (about 3 ohms on standard E3L) and E is connected to D across the armature.
To illustrate, the lowest reading I get across the F and D terminals on a good spare dynamo here is 4.5 ohms, which goes up in certain positions of the armature depending on how good the brush contacts are with the commutator.  But if you had zero ohms  . . . even a cheapo meter ought to register the difference between 0 and 4 or more . . . then that would tell you there's a problem.

I don't know what you should be seeing between the leads attached to the DVR, disconnected, as haven't got one handy without removing a seat and fishing one out. But not sure I'd understand what the readings told me anyway, beyond my pay grade.

[Rex]

As an aside, I've found that an old analogue meter (AVO Mk8 to be precise) is better when testing working dynamos. DVM's, great as they are, seem to fluctuate more when testing output, probably due to the nature of the comm and brushes.
I've never really gone along with the idea that a nominal 6V dynamo can be satisfactorily run at 12V without any mods.
Nuffink is for nuffink, as they say in the world of Physics.

[groily]

Agree that analogue AVOs are absolutely great Rex, but as per my tests yesterday, I saw 'rock solid' on a decent digi-meter when regulating. Little bit spiky on the way up from base voltage, but pretty linear for all that and none of that 22v spikey thing. Good on alternators as well, and  also very steady measuring low tension voltages being generated on magnetos, which is something I measure now and then.
A cheapo £5 meter I use for simple fault-finding / continuity testing and carry in the toolboxes is comparatively hopeless, but it is still 'indicative'.

What Musky needs to do here is 'Trust the Ammeter' though - the thing seems to be running unregulated or poorly regulated, which will be for one of the two reasons under discussion, ie wiring fault at dynamo or failure of field driver in the DVR2.
Best to start at the source with these things - which means dynamo checks first now that the battery itself has been ruled out. A wiring fault between D and F would cause the same trouble regardless of the config of the dynamo and a fine-wound dyn would probably have melted if it had been allowed to produce the sorts of charge rates seen by Musky.

I don't really agree about not using nominal 6v dyns at 12, but fully accept there are 2 schools of thought. (Three if you include Altons.) I must have done over 100,000-odd miles on standard E3Ls over the past 20 years on my A and my AMC twins. Yup, there is the physics in there, natch, but it's not just Ohm's law at work, what with back emfs and all that good stuff having a bearing.
Low resistance fields get loaded running at 12, but the standard armatures are tough and support high continuous loads well . Of course, there's the high speed cut-in downside which is a big part of the raison d'être for the finer windings, but that downside is OK for country boys who don't ride round town much in the dark. I've had to replace an armature or two, some brushes and bearings and oil seals, plus one entire monkey-metal brush-end housing that snapped, but never (yet, touch wood) had a field winding die. Horses for courses I reckon, and whatever one is comfortable with.

[muskrat]

G'day Bill.
Thanks for that info. Working up the chain of command sounds right.
As I've said electricks aren't my forte.
Sorry off topic. Going for a ride to clear my head for the w/end on the rHonda. 600Km to the 50th anniversary of the movie Stone. https://www.youtube.com/watch?v=utz7CImMXdQ
Cheers

[muskrat]

G'day Bill.
I bought a cheap analog multi-meter (faulty only measures DCv) and did the test again.
With the amp gauge disconnected and + lead to the wire and - to earth.
Idle + 0v, cuts in at 1500rpm = 6v, 2000rpm = 11v, 2500rpm = 12.5v, 4000rpm = 14.5v over those rpm stable at 14.5v.
With the amp gauge connected and wire on the feed post voltage the same, at 3000rpm the gauge reads 4 amps and at 4500rpm reads 8 amps That's with only the ignition (Boyer MkIV) drawing power.
New DVRII on it's way but I'm not sure it's the problem now.
I'll test the dynamo output tonight.
Cheers

[groily]

Interesting Musky. Those voltage readings aren't unreasonable, and would suggest the regulator is OK - but the ammeter readings aren't.
I wonder if the ammeter itself  has gone awol for some weird reason?
What does the ammeter say if you switch on the lights with the engine stopped?

If we assume - guessing here - you have a 36W headlamp, and then a 5W tail plus a sod-all 2W for the speedo, you'd expect to see a discharge of about 3.5 amps at 12v. If the thing shows way more, then the ammeter is faulty or there is a wiring fault which is draining the battery elsewhere. (Not a dead short, or there'd be sizzling, but maybe something weird.)
If you have a spare ammeter sitting around, you could swap it out? Or you could play with that ammeter on the bench, with a bulb of known wattage and a battery, to see if the readings were sensible. 36W bulb -3 amps, 60W bulb -5 amps, etc.

I suspect the dyn is actually OK from those voltage readings, as it's cutting in about right and is not running out of control the way I worried it might be. If it were really chucking out 8 amps plus the power for the Boyer (2 amps minimum?) it  would be loaded beyond its safe range, because 10 amps at 12 volts = 120 Watts worth of oomph. Far more than is good for it - and it wouldn't do it for long I don't think.

You could use your digi-meter on the amps setting (usually means plugging the leads in differently at the meter) and measure the current from A to the battery, but most meters are only good to about 10A, so if the system was truly slinging out the sort of current the ammeter suggests, you could blow the fuse on the meter I suppose!

If the ammeter tests accurate, and the dyn tests good (as I think it will now), then there is still a problem. A wiring problem of some sort, because there is just no way you should be seeing those current readings while also seeing the voltage figures you've quoted! It says there is a big drain somewhere which the dynamo is being asked to compensate for. Areas to look at would include the brake light set up, the horn, and the ignition wiring for the Boyer I suppose  . . . . bit hard to say. But has to be summat.

[muskrat]

I'm back.
The dynamo tested OK. At 3000rpm measured 30 volts with F & D connected to the multimeter + wire and - wire to earth.
Cheers
G'day again Bill
Saw your reply as I was about to post this.
You may be right about the ammeter, it's a cheap Oriental job. I don't have a good one (the Cafe is set up with a red light until the charging outweighs the draw).
You'd  if you saw my wiring 
Cheers

ps: don't buy one of these https://www.ebay.com.au/itm/314678921353 the only thing that works is DCV

[groily]

Back too Musky. Just nipped to local bar for some necessaries. (Public Holiday here in la belle France, All Saints Day and all that, in a secular country what's more  ? ? ?) Luckily, my 'necessaries' don't include normal shops much  . . .

Anyway, that's a heck of a dyn you've got - 30v says it's got its cojones attached where they should be all right (don't run it unregulated like that for too long - it can have too much of a good thing!)

Maybe risk hooking up your other meter on the amps scale in place of the ammeter to see what it shows? But it's starting to sound as if the cheapo one is a likely source of what is a non-problem after all.

Suggest maybe also repeating engine running tests with brakelight and horn disconnected though if they're wired straight off the batt (as normal) 'cos any unwanted current draw / short will show up as a 'charge' on the ammeter as the system compensates for the drain. If the wires to the a*se of the bike run under the mudguard  . . . . common source o' grief.

[muskrat]

G'day Bill.
 Just about ready to say phu(k it. Hooked the digi thing instead of ammeter. At 4000rpm got 4 amps with nothing on but the Boyer.
New DVRII arrived today 11 days after order I can't get parts local in that time It'll be a spare for now.
No rides this weekend so may strip all the wires out and start from scratch 
Thanks heaps for your help.
Cheers

[groily]

First thing I said this morning musky was also phu(k it, as we're having a bit of weather just now. Stuff all over the place, including the odd tree. Even a 14kg gas bottle blown off it's moorings from my BBQ for chrissake! But hey, roof still on, and power restored after a 5 hour cut just now, so don't have to bugger about in the sheeting rain setting up my gennie.

Anyway, maybe swap the DVRs and see what difference if any, before ripping out all the wiring. Unless it's that bad it needs it regardless!
The one on there did seem to be regulating from your tests from the A wire to earth, but now you have another one, might as well play with it.

I still suspect an unwanted load not passing through the ammeter, but not a dead short, is involved. Because if prior to all this the ammeter behaved, the system charged, the sparks flew and Life was Good, something happened to give you those high ammeter readings - which you've now proved are real.
If there isn't a D to F short at the dynamo, or a fault inside the regulator (and there doesn't seem to be), and if the battery is well charged (which it is) - then the ammeter and your digi-meter are both telling us that there is something weird somewhere or other. But as ever, where and why? I would def disconnect any item that is fed direct from the battery, ie doesn't go through the ammeter, for starters. I also am starting to wonder how the BB system is wired in and/ or if anything has changed there? Because if THAT isn't through the ammeter, you'd see a high charge rate on the ammeter, equivalent to the ignition load plus a bit to charge the batt.
Good luck mate!

[muskrat]

G'day Bill.
The weather seems to be crazy all over. You lot up there with storms/floods, down here fire season has started early.
I will swap the DRVII over the w/end. It's been that long since I converted to 12v and Boyer I can't remember how it was all wired. Test light and mm will get a workout.
Cheers

[KiwiGF]

If the ammeter is in any doubt you can perform a crude check of accuracy using a bulb eg a 35 watt bulb should take 2.92 amps at 12 volts. To find the approx amp requirement for any 12 volt bulb just divide its watts rating by 12. This works for 6 volt bulbs as well, but divide the watts by 6.

It’s definitely worth a check as voltmeter I bought off amazon UK a couple of months back just gave the voltage of a new standard AA battery  as 2 volts when on the 0-2 volts range setting (obviously incorrect for a 1.5 volt battery), and 1.5 volts (its 1.65 on my other expensive voltmeter) on the 0-20 volt range setting.

Odd electric issues can occur due to aftermarket “lucas” ammeters fitted on the bike, a few A65’s I know have broken down due to intermittent open circuits and high resistance with aftermarket ammeters.