Lotus Elan

Alternator wiring

PostPost by: Mrozik » Tue Apr 02, 2024 2:23 pm

Hi All

I need some urgent help please

I'm in the process of converting the dynamo set-up to an alternator system. The changes to the wiring for the control box seem straight forward enough but I'm having a problem knowing which wire goes where with the alternator.

The old dynamo just had two wires but there are three connection for the alternator!
See photo

I bought a alternator replacement from a reputable Lotus parts supplying but they can't help!

Many thanks
John
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Back of alternator.jpg
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PostPost by: Craven » Tue Apr 02, 2024 2:34 pm

Only two wires used. If you look I think you will find the two large connectors are joined together and are output other small goes to + 12v via the charge indicator light.
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PostPost by: Mrozik » Tue Apr 02, 2024 2:48 pm

Many thanks, I was hoping it was simple. What confused me was that the alternator was supplied with 3 connector and when I checked what google had to say it really got complicated!
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PostPost by: alan.barker » Tue Apr 02, 2024 6:08 pm

The original Generator was 22 Amps so wiring was for this.
When i fitted a 45 Amp Alternator i used the spare big connector to run a new cable to where all the cables meet at the Solenoid Terminal. Thereby doubling capacity. I used a brown cable and tywraped along cable run to be neat.
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PostPost by: JonB » Wed Apr 03, 2024 8:13 am

alan.barker wrote:The original Generator was 22 Amps so wiring was for this.


Thanks for that Alan, I was wondering myself. Indicates that a 45A alternator will suffice.
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PostPost by: alan.barker » Wed Apr 03, 2024 8:55 am

Hi Jon,
I gutted the Voltage Control Unit and cross connected inside. Voltage Control Unit still on bulkhead likes like original and tidy.
Alan
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PostPost by: Mrozik » Wed Apr 03, 2024 1:35 pm

Hi All

I thought I was there but I now I have some doubts so greatly appreciate some clarifications.

Please see attached diagrams

With the new set-up is it right that

1. there's no solenoid connection?
2. there's no connection to the ignition tell tale bulb?

Thanks
John
Attachments
control box (after).jpg and
control box (before).jpg and
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PostPost by: Mrozik » Thu Apr 04, 2024 9:16 am

I was also wondering whether I should find another attachment point for the earth wires previously connected to the control box?

I’m stuck at the moment

Thanks
John
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PostPost by: Andy8421 » Thu Apr 04, 2024 3:04 pm

John,

There are a number of threads on this forum and other British sportscars (MG and Triumph) forums about this conversion. I would have a look at those first to become familiar with the basics.

In summary, it all depends how much you want to mess with the existing wiring. Installing an alternator itself is very simple, a thick wire (from either of the two big terminals on the back of the alternator) needs to go to the battery, a thin wire (from the small terminal) needs to go to the ignition warning light.

Most people piggyback on some or all of the existing wiring to achieve this. The control box becomes redundant if an alternator is fitted, but it can become a convenient junction box to access all the necessary wiring to save installing any extra cables.

Have a look at the forum for details, if you are still struggling come back and I can answer specifics.

Andy.
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PostPost by: Mrozik » Thu Apr 04, 2024 4:10 pm

Hi Andy

I did quite a bit of research before I started but some of the info I found was either contradictory or just confusing,

Your comments however makes me think that I've almost got it right apart from not connecting the brown/yellow wire (ignition tell tale wire) to the smaller alternator connection (I connected the original brown/green wire instead)

I also connected the original thick brown dynamo output wire to terminal B on the control box but as someone else suggested, I also run another thick wire from the second large alternator connection directly to the solenoid. Hopefully these two thick wire will be sufficient to take the higher current?

Thanks
John
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PostPost by: alan.barker » Thu Apr 04, 2024 5:14 pm

20221020_091904.jpg and

Control Box gutted and cross connected inside. Put back on bulkhead looks original
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