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dynamo E 3LM

The resistance of the field coil is 2.5 Ohms with the + of the multimeter connected to the "F" wire and 1.9 Ohms with the - of the multimeter connected to the "F" wire. Is this normal Furthermore on the bench with a drill at "full speed" I get only 5 or 6 Volts Is it time for a new field coil and/or armature.


John

email (option): john.kater@chello.nl

Re: dynamo E 3LM

Hi Johan,

You can find useful info here:

http://classicrider.dk/dokuments/Lucas/1953%20Lucas%20Dynamos%20E3L%20E3LM%20E3N%5B2%5D.pdf

http://www.britishonly.com/pdf/bsa/sectionY_BSAservicesheetno809.pdf

http://www.audioworld.net/BSA/manual54/generator.pdf


As to the field:

Resistance should be ~2.8 Ohams.

The resistance should be measured when the field wires are not connected (At least one of them)
and Ohm meter connected across them, so Ohm meter polarity should no be a factor.
(Unless the dyno has a VERY strong magnetic field)
In the manuals above you can find a way to test field using the ammeter.
(Ammeter should read about 1.9A when running 6V through field SHORTLY, with Ammeter connected inline)

Noam.

email (option): Noam10@gmail.com

Re: dynamo E 3LM

Thanks Noam for the info. I made a better connection to the drill (2700 rev.) and got 9 Volts max. I hope it is enough. Will a good dynamo give more ? Of course when in the bike and running it will go faster, because of the sprocket sizes. John

email (option): john.kater@chello.nl

Re: dynamo E 3LM

Hi Johan,

according to the info on the first link in my first reply,

An E3LM dynamo should give an output of 8.5Amp @ 7Volts
when load resistance is 0.82 Ohm (Almost a short) and 1850-2000 RPM of dynamo.

If you got 9 Volts on 2700RPM, it may be a little low,
But can't say I am sure.

Dynamo should also have the correct brushes and even spring tension in order to get best output.

The ratio of engine revs VS dynamo revs is about 1:1.25,
so at 2000 engine revs, the dynamo rotates at about 2500RPM.

A good dynamo should reach quite easily a 14.4 Volts,
if system is converted into 12Volts, by replacing the regulator,
But of course- in higher revs than you would get the 7.2Volts for 6V system,
so it would be hard to get a charge in a in-town drive.

In order to test max voltage output,
the "F" and "D" terminals should be shorten together,
and then measure the voltage between them (shorten) and the body of dynamo.


Hope that helps..

Noam.

email (option): noam10@gmail.com

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