Dynamo not charging

General electrical problems
Michael.Brown
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Dynamo not charging

Postby Michael.Brown » Tue Apr 07, 2020 7:31 pm

Hi all,

With no riding for the foreseeable future it is time to get to the bottom of my lack of charging problems on the WNG.

It's fitted with a Lucas E3HM Dynamo operating in the opposite direction to the arrow on the housing and +ve earth. Motors off the bike in the correct direction, but has only 0.25V output at approx 500 rpm when driven by a battery powered drill.

Question is does it normally run at engine speed or due to the gearing or slower or faster? Any ideas?

Mike
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1942 Ariel W/NG
1960 Ariel Arrow
1960 Ariel Leader
1963 LE Velocette MK3

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chris.vredenbregt
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Re: Dynamo not charging

Postby chris.vredenbregt » Tue Apr 07, 2020 8:04 pm

I would clean the collector first and the grooves too then check if the brushes are not greassy before going further
black ariel model G special 1930 500 OHV

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Re: Dynamo not charging

Postby Simon.Gardiner » Tue Apr 07, 2020 8:29 pm

I think it needs to be said that just because one of these dynamos 'motors' there's no guarantee that it'll actually produce power under load. (Odd though that might seem - and speaking from experience.)

SG
'55 Huntmaster, '56 VH, ' 51 VH, '80 R100RT, '00 Sprint ST (but all those Ariel parts can only make one running bike...)

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Re: Dynamo not charging

Postby will_curry » Tue Apr 07, 2020 8:38 pm

Make sure the dynamo body is earthed properly to the magneto - all that
black paint makes me nervous . . .

Michael.Brown
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Re: Dynamo not charging

Postby Michael.Brown » Tue Apr 07, 2020 9:19 pm

Should the casing be a non painted finish then?
1942 Ariel W/NG
1960 Ariel Arrow
1960 Ariel Leader
1963 LE Velocette MK3

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alan.moore
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Re: Dynamo not charging

Postby alan.moore » Tue Apr 07, 2020 11:59 pm

Michael
Worth going through the post John Nash did viewtopic.php?f=8&t=189 on the forum. This should explain most faults/procedures to find out where the fault lies.

There are also Lucas documents on the club website here http://www.arielownersmcc.co.uk/members ... /Lucas.htm look at the one re Generators. Yours is similar to the E3N

And another good guide to dynamos here https://matchlessclueless.com/electrica ... as-dynamo/


Couple of observations/thoughts:
The WNG was originally negative earth (as were the pre and immediate post war singles). This will not alter whether the dynamo charges or whether the electrical system operates but worth bearing in mind.

Standard Ariel dynamo was clockwise rotation (viewed from the drive end) and the arrow on the body would therefore point in this direction. If (like mine on my WNG) your arrow points anti-clock you have to alter the internal connections (swap the field coil wires). If yours motors clockwise (viewed from drive end) on a battery ( F and D terminals bridges) then the change must already have been made. It is worth checking how the internal wires are connected though for peace of mind.

Here is a post which looks into this https://www.a7a10.net/forum/index.php?topic=12832.0

If the dynamo has not been in use for some time it will need the magnetism reinstating before it will charge (flashing/re-polorising) . Johns post explains how. You need to bear in mind Pos or Neg earth i.e if Pos earth then the positive cable from battery needs to go to the dynamo body and the neg lead briefly touched to the F terminal on Dynamo.

The body needs to have a good electrical contact with the magneto body it is clamped to as this is how the dynamo connects to the Earth side of the electrical system. The bodies were ( I believe) originally Cadmium plated. Any paint on the body will mean a poor or no electrical connection.

Also worth bearing in mind that the Mag also needs a good earth. There is normally a screw terminal lower left side on the points side. I run a wire from this to an engine mounting bolt and /or a separate wire to the main frame earthing point on top of frame under the seat.

And finally...500 rpm is not fast enough to get the dynamo to start charging, you need at least 1000. I use a mains electric drill with a variable speed trigger, my battery drill is not fast enough.

That should be enough to keep you busy for a day :)

Cheers
Alan
1939 VH Redhunter;1942 RN WNG;1951 Triumph 6T Thunderbird;1970 BSA B175 Bantam;1986 Yamaha SRX600 single
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alan.moore
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Re: Dynamo not charging

Postby alan.moore » Wed Apr 08, 2020 1:14 am

Oh and re the speed the dynamo turns at:

Mag gear has 58 teeth and is driven at 1/2 engine speed

Dynamo gear has 22 teeth so turns 2.6 times for 1 turn of mag gear

So dynamo is driven at 1.3 X engine speed

eg: Engine 2000 rpm X 0.5 = mag gear 1000 rpm X 2.6 = dynamo gear 2600 rpm = 1.3 X 2000 engine speed

I think :roll: ...it is getting late...someone please correct if wrong !
1939 VH Redhunter;1942 RN WNG;1951 Triumph 6T Thunderbird;1970 BSA B175 Bantam;1986 Yamaha SRX600 single
http://cloggymoore.wix.com/triumph-pre-unit-6t

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Re: Dynamo not charging

Postby nevhunter » Wed Apr 08, 2020 2:24 am

Go back to John's coverage. as said. it's all there. Often I have to give a bike quite a few revs to get the mag to charge after sitting. Once you do it it's OK from there on. Always check bearings for play and the bush may come loose The little bush is sintered and the commutator end may warp and allow polling of the armature. Your brushes should be free to move and the commutator running dead true (use a fixed steady in the lathe) and undercut it properly and not had too much diameter removed from it. IF it's well undersize you will have trouble with the brushes alignment,. I have the lights etc working on all my Ariels with standard components and 6Volt but have put a bit of work and new parts in as well but I don't ride them at night. The original types of regulator work too.The later one (Taller) will work on both 2 brush generators. It incorporates a resistor which reduces erosion of the regulator points.Nev

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Re: Dynamo not charging

Postby Michael.Brown » Thu Apr 09, 2020 6:21 pm

Thanks for all the information guys especially Alan for the gearing information.

Update: After two years of no output from my Dynamo, and with time on my hands I have finally got everything working. To say I am chuffed would be an understatement! :D

I found it easier to take the Dynamo off, and up on the bench. I cleaned the brushes and made sure they moved freely, re-polarized the Dynamo (flashed across the battery half a dozen times just to be sure), the case to the positive terminal and F to the negative terminal of a spare 6V battery (my system is positive earth).

Then I checked the resistance of the Field Winding which came out at 3.2 ohms and the Dynamo Winding which registered 0.6 ohms. It motored correctly off a 6V battery and in the right direction.

Finally I linked the F and D terminals, connected a 12V test bulb between the link and the case (earth) and spun the Dynamo up to 3000 rpm and got a good glowing bulb. A multimeter connected the same way registered a smooth increasing voltage to over 7.7 V at 3000 rpm.

Final test was back on the bike and started the engine and checked the Ammeter for charge and re-checked the voltage readings with the multimeter with the Headlamp switch in all 3 positions. At a little over fast idle the Dynamo was charging at well over 6.55 volts in the off and pilot position and balancing the Headlamp in the Main position. Happy Days.

I should add that I have an AO Services Electronic Regulator positive earth hidden inside the original Regulator Box.

Well worth the couple of hours spent sorting this. :D

With grateful thanks to Matchless Clueless and I hope this is of some help to others!
1942 Ariel W/NG
1960 Ariel Arrow
1960 Ariel Leader
1963 LE Velocette MK3

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Re: Dynamo not charging

Postby pappleton » Tue Apr 28, 2020 9:41 am

When I recommisioned my '53 VH after sitting in the shed for some 30yrs, nothing I did could encourage a good charge from the dyno. Before being laid up, the bike had the best charging rate I'd seen on a 6v system - you could even take it out at night! A few pointless hours were spent prodding and poking, checking and glowering at the dyno and regulator, it all seemed to be doing what it was supposed to. As it was on one of the rare sunny days we blessed with, I went for a 80 mile ride. Glory be! By the rides end all was working. Could it be that 'lost' magnetisim is somehow restored with use?
BR,Paul
Paul Appleton '53 VH plunger, '53 VHA rigid - in many boxes, '58 H.D. pan/shovel rigid


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