The BSA A7-A10 Forum

Technical => Lucas, Electrical, Ignition => Topic started by: RogerSB on 23.05. 2018 20:39

Title: Ammeters
Post by: RogerSB on 23.05. 2018 20:39
Hi all. I’m considering changing my ammeter because the needle on my Lucas ammeter is not in the middle when it’s ‘at rest’. It may seem a minor thing but it bugs me beyond belief because it’s not as it should be and as a consequence it’s very hard to see if it’s actually showing a slight charge or discharge from the riding position (see pics).

Secondly, it’s 8-0-8 and originally for 6v. My GF is now 12v.

I know ammeters only measure the current flow and are not fussed about being wired 6v or 12v and my understanding is, that with a E3L dynamo with an output of 60w combined with a 12v battery = 5 Amps, so an 8 Amp ammeter is up to the job but has anybody got any idea if the 12-0-12 versions brought in for the later alternator models show any significant difference in the deflection of the needle with 12-0-12 as opposed to the 8-0-8 ammeter?

Also anybody got any recommendations on decent ammeters currently available based on their recent experience?

The hole in the 1960 GF nacelle is to take a 1 3/4” (45 mm) diameter ammeter, so a Miller type isn't an option as I don’t want to file the hole bigger.
Title: Re: Ammeters
Post by: chaterlea25 on 23.05. 2018 20:56
Hi Roger,
Gravity ??

John
Title: Re: Ammeters
Post by: RogerSB on 23.05. 2018 21:13
Thanks for your reply John, yes I know and at one time I had the needle pointing down (see photo) and it did help a little.

Edit: I'll probably end up turning it again.
Title: Re: Ammeters
Post by: RichardL on 23.05. 2018 21:28
Roger,

Is there a centeting adjustment screw on the back of the ammeter? Not saying I'm the best source on this (despite my E.E.degree), but I would stay with the 8A version. As you note, cureent is what is being measured.  In the 12V system you'll draw half the cureent for the same wattage. With the 12V system  and 12A meter your needle deflections will be notably smaller, making it trickier to judge charging rate and changes in charging rate.

Richard L.
Title: Re: Ammeters
Post by: RogerSB on 23.05. 2018 21:38
Hi Richard, thanks for that. I knew 6v (with its thicker wiring) carries twice the current of 12v but I couldn't fathom out what the effect would be on the needle. There is no adjusting screw on mine, it's a completely sealed unit in a metal case.
Title: Re: Ammeters
Post by: Greybeard on 23.05. 2018 21:52
Roger, are you able to check that the ammeter is at fault, rather than an electrical problem? I imagine if you put a low wattage light bulb across the ammeter connections you should see it glow when current flows either way through the meter. More accurate would be a multimeter set to amps/milliamperes.
Title: Re: Ammeters
Post by: RogerSB on 23.05. 2018 21:57
Hi GB, thanks for reply. Ammeter is working ok, it's just that I don't like the needle being off centre. Absolutely silly, I know, but it contantly causes me some irritation.

I know if I replace it I could easily end up with the same problem!
Title: Re: Ammeters
Post by: Greybeard on 23.05. 2018 22:07
You might try placing a small magnet near the ammeter and see if you can influence the needle position.
Title: Re: Ammeters
Post by: morris on 23.05. 2018 22:09
I would kindly offer you a swap with mine but that won’t help much because it’s showing exactly the same deflection as yours...
Still don’t know why it does that but decided to live with it. Gives me the feeling that there is some charge when the pointer is on zero *smile*
Title: Re: Ammeters
Post by: Greybeard on 23.05. 2018 22:15
My ammeter is aligned with zero at the top.
Title: Re: Ammeters
Post by: morris on 23.05. 2018 22:31
Forgot to mention but mine is a new one I bought a couple of years ago. It looks exactly like yours with the “LUCAS” and “Made in England” print.
It may be of the same batch/manufacturer?
Title: Re: Ammeters
Post by: KiwiGF on 23.05. 2018 22:45
Hi all. I’m considering changing my ammeter because the needle on my Lucas ammeter is not in the middle when it’s ‘at rest’. It may seem a minor thing but it bugs me beyond belief because it’s not as it should be and as a consequence it’s very hard to see if it’s actually showing a slight charge or discharge from the riding position (see pics).

Secondly, it’s 8-0-8 and originally for 6v. My GF is now 12v.

I know ammeters only measure the current flow and are not fussed about being wired 6v or 12v and my understanding is, that with a E3L dynamo with an output of 60w combined with a 12v battery = 5 Amps, so an 8 Amp ammeter is up to the job but has anybody got any idea if the 12-0-12 versions brought in for the later alternator models show any significant difference in the deflection of the needle with 12-0-12 as opposed to the 8-0-8 ammeter?

Also anybody got any recommendations on decent ammeters currently available based on their recent experience?

The hole in the 1960 GF nacelle is to take a 1 3/4” (45 mm) diameter ammeter, so a Miller type isn't an option as I don’t want to file the hole bigger.

An 8 amp ammeter should be fine, but for the record it is generally accepted the e3l can provide more than 60watts when working at 12v  *smile*

See http://dynamoregulators.com/documents/improved%20charging%20for%20BSA.pdf

I think the technical reason may lie in the fact the “waste” heat created by the dynamo is directly proportional to the current going through it, and the voltage does not affect the amount of heat generated, and it is this waste heat that limits the dynamos output capability.
Title: Re: Ammeters
Post by: Rex on 24.05. 2018 09:28
Some years back it wasn't unusual to hear of 6V-12V dynamo conversions that had got so hot that they'd melted the soldered connections on the commutator.
To get any near approaching those sort of temperatures is cruelty to old machinery.
Title: Re: Ammeters
Post by: RogerSB on 24.05. 2018 10:54
You might try placing a small magnet near the ammeter and see if you can influence the needle position.

Thanks GB, I've already tried that. It does pull the needle well over to the plus side but when the magnet is taken away it just springs back and it would be a right old bodge to have to permanently stick a magnet in place inside the nacelle.

Forgot to mention but mine is a new one I bought a couple of years ago. It looks exactly like yours with the “LUCAS” and “Made in England” print.
It may be of the same batch/manufacturer?

Maybe be a 'last day of term' batch from Lucas *conf*. The ammeter was already on my bike when I bought it and it's always been like it - and gradually driving me paranoid *eek*. Bike is pretty much original but no doubt it is a replacement. Maybe an Indian fake?
Title: Re: Ammeters
Post by: RogerSB on 24.05. 2018 16:11
Here's a sequel which definity explains my dodgy ammeter.

Look at the photo carefully and you will see that the Lucas face has actually been overprinted on one that originally was printed Royal Enfield. My camera showed it up as it's not visible with the naked eye (well, not mine anyway). It puzzled me at first and then it dawned on me and I went looking and came across this horrible cheapy one for under £8.00 which shows the exact design that I can see underprinted on mine  *pull hair out*.

My conclusion is that my ammeter stamped Lucas and Made in England is anything but - and is a fake.  The manufacturer (probably somewhere in India) has even used up surplus bits or offcuts to manufacture a batch of fake Lucas ones.

It goes without saying I'll be replacing it.


Title: Re: Ammeters
Post by: cyclobutch on 24.05. 2018 16:15
Good spot, thickening plot.
Title: Re: Ammeters
Post by: Greybeard on 24.05. 2018 18:04
Cheeky buggers!
Title: Re: Ammeters
Post by: RogerSB on 24.05. 2018 19:55
Yep! And it shows how you can be fooled.
It was on the bike when I purchased it and I've always believed it to be an original Lucas. Even looking at the body it looks right and well made and the chrome bezel is pressed on underneith all around the diameter (i.e. not held on by a few turned over tabs).
Title: Re: Ammeters
Post by: morris on 24.05. 2018 20:04
Well well, my my... that’s a definite guilty your honor!
Title: Re: Ammeters
Post by: duTch on 24.05. 2018 22:07

 
 Maybe the sticker sticker-onner had a liquid lunch and your's was first off before he 'got his eye in'   *smile*?

  Other than that it may be a perfectly good meter, but I guess removing the bezel and re-aligning the sticker is not an option....I'd probably have a go myself- nothing ventured, nothing gained- and nothing to lose, might just look a bit used *smile*
Title: Re: Ammeters
Post by: RichardL on 24.05. 2018 22:26
If it's headed for the bin anyway, I'd put on my fantasy watchmaker hat and have a go at the mechanism.

Richard L.
Title: Re: Ammeters
Post by: chaterlea25 on 24.05. 2018 23:37
Hi Roger,
The current "Lucas" stuff is not made in UK its just boxed Lucas by Wassel who own the name
The Lucas ones are plastic with the bezel held by 4 tabs, original crap *ex*
The enfield one looks better made  *eek*

John
Title: Re: Ammeters
Post by: Triton Thrasher on 25.05. 2018 06:37
Get the chrome ring off and bend the needle, if there isn’t a centring adjustment in the mechanism.
Title: Re: Ammeters
Post by: RogerSB on 25.05. 2018 07:57
Well I've turned it 90 degrees left again to leave gravity to work its magic.
Thanks for all the advice, appreciated. It seems such an insignificant thing compared to poor GBs problem *sad2*.

The current "Lucas" stuff is not made in UK its just boxed Lucas by Wassel who own the name
John

Thanks John, I recently noticed that on Classic British Motorcycles.com website - with some surprise, as it's the only company I've come across that actually mentions that it's manufactured by Wassell. Everyone else I've come across states Genuine Lucas, which then leads you to believe it's actually manufactured by Lucas and not simply licenced by them.
Title: Re: Ammeters
Post by: duTch on 25.05. 2018 09:01

 
Quote
Classic British Motorcycles.com

 Gone Dodgy unless they can prove themselves legit
Title: Re: Ammeters
Post by: RogerSB on 25.05. 2018 09:27

 
Quote
Classic British Motorcycles.com

 Gone Dodgy unless they can prove themselves legit

 *eek* Thanks for the 'heads up'. I've never bought anything from them - was just searching to see what was available and noticed that CBM state Wassell as the manufacturer of 'Genuine'  *rant* Lucas ammeters.
Title: Re: Ammeters
Post by: duTch on 25.05. 2018 13:40
 
Quote
....state Wassell as the manufacturer of 'Genuine'  *rant* Lucas ammeters.

 Sounds familiar, I did some searching a couple off years ago to see who owns what,  and I think same goes for 'Lucas', but can't be certain

 *edit*; I just realised Chaterlea John already covered it ^^ *shh*
Title: Re: Ammeters
Post by: Greybeard on 25.05. 2018 15:00
Roger, while I was rummaging in my shed I found the presumably original Lucas ammeter from my bike. It looks like it might be ok, but would need a good clean. The back has a diameter of 1 5/8". This may be too small for your needs but if it's any good you can have it.
Title: Re: Ammeters
Post by: RogerSB on 25.05. 2018 16:51
GB,  *thanks*  that's really kind of you but this morning I ordered  *computer*  an 8-0-8 not Lucas but a 'genuine unpretentious made in the UK' replica with a metal case.