Dynamo to alternator .

[surfergirl]

While we are locked down decided to sort some stuff on the van. Swapping the dyno for an alternator seemed like a good idea, most places online are out of stock for the kit i.e loom , bracket, belt and alternator.
Can I just get the correct alternator online and then make up the wiring? If so which one ? One for a mini maybe , any part no.s
Thanks
Hopefully this may keep my mind occupied and stop me losing the plot!!

[paul 300358]

You need a right hand side, you could give https://www.bowerspartsonline.co.uk/ a ring, they have suitable alternators on their site. They probably have the leads. Mine is fitted with a https://www.ebay.co.uk/itm/Gates-Fan-Be ... 2749.l2649. Don't fit a cheap one from the usual suppliers as they are very noisy, I have had to swop 2. Let me know if you want a wiring diagram emailed, I have one somewhere.

[oliver90owner]

Wiring diagram? Very simple: one heavy lead to battery live side and the other to the ignition warning lamp (do not use a LED for this as it energises the field at start-up). Look at the ‘stickies’ on the forum at the top of the thread list.

[surfergirl]

Thanks, looks like the kits are still out of stock at esm, so will have to get the bits separately.
So what output alternator? wire size ?
I'm guessing a classic mini will work, it seems stocks online are low due to either the pandemic or brexit or bofh.I

[surfergirl]

Hi folks,
Got the new alternator in the post today, but couldn't get the loom to wire it up because ESM say the supplier isn't working due to the pandemic.
I have a diagram with the kit, the alternator has two big spade connectors and one small.
It says one thick wire to solenoid, one thinner wire to solenoid and one thinner wire to warning light.
So couple of questions, how thick a wire? And does it matter which large spade to connect to on alternator.
Where in the loom is best to join to the warning light.
Diagram says disconnect F and D on control box.
Thanks for your help.!

[les]

Here is a wiring diagram that may assist you.

024111AF-438B-4A34-817B-2B47019FADE4.jpeg (174.12 KiB) Viewed 2802 times

[surfergirl]

Thanks for the diagram, it's cool but I've got two live connectors on the Alt. Also need to know where best to connect to the warning light.
Thanks.

[geoberni]

Quite simply, you've already said you have 2 Large Spade terminals, and 1 Small Spade terminal.

You'll see from the diagram Les provided that you have 2 cables connected.
Unsurprisingly, the thin cable that is only connected to the warning lamp goes on the small connection.

As to the thick output cable, it should be able to go on either of the B terminals, as they are almost invariably connected together.
There are some vehicles that require the extra output, take a close look, I'd bet they are linked.
Are you going to use an actual Plug connector?
https://www.autoelectricsupplies.co.uk/product_list/258
I'm guessing your purchase is of the Lucas/Bosch type?

Cable size, whatever is a higher rating than the Alternator .

Where to pick up the warning light connection? Why not repurpose the discarded one that was going to D on the regulator?

[LaughingBoy]

how thick a wire?

There is a misconception that you automatically need a cable to match the alternator's rated output - so e.g. if you had a 18 ACR 45 AMP alternator then you'd need a cable capable of handling 45 amps. This is not the case. An alternator will only output what is demanded of it. On a Minor with standard electrical equipment the load with headlights, heater and wipers all turned ON, the electrical load is less than 20 amps. The standard wiring should be sufficient. The original Minor dynamo put out a maximum of 22 amps.

So the size of the cable is dependent on the maximum electrical load NOT the alternator's potential output. If you have extra circuits e.g. a heated rear window and electric cooling fan then you could run a thicker cable. An excellent alternative option is to run the headlights directly from the second alternator output terminal via relays. This keeps a big chunk of current (about 10 AMPS) completely separate from the alternator/solenoid cable. There are other advantages too - less voltage drop for the lights and there is no current running through the dashboard headlight switch.

Graham

[geoberni]

how thick a wire?

There is a misconception that you automatically need a cable to match the alternator's rated output - so e.g. if you had a 18 ACR 45 AMP alternator then you'd need a cable capable of handling 45 amps. This is not the case. An alternator will only output what is demanded of it.

Graham
I'd agree with you to a theoretical point, but equally when dealing with people who don't know much about electrics, I'm extremely cautious of them under-rating their main feed.
Your argument is great until they decide to add a couple of Spotlights or a heated read screen to the car and they've only used 25 Amp feed.

Or what if they have a totally flat battery one day and jump start the car; the flat battery could happily try and pull 20+ Amps if there's a 45A Alternator fitted.

[LaughingBoy]

I was waiting for someone to mention flat batteries pulling a lot of amps! You make fair points and to be on the (very) safe side a thicker cable can be used which also future proofs for any added circuits.

In practice, I've had an alternator for decades and never had any problems with the existing cabling. I have an electric cooling fan (about 8 amps) fitted and my 60/55W headlights are powered from the second alternator output terminal. I keep my battery charged up and all is OK ...

Graham

[geoberni]

I was waiting for someone to mention flat batteries pulling a lot of amps! You make fair points and to be on the (very) safe side a thicker cable can be used which also future proofs for any added circuits.

In practice, I've had an alternator for decades and never had any problems with the existing cabling. I have an electric cooling fan (about 8 amps) fitted and my 60/55W headlights are powered from the second alternator output terminal. I keep my battery charged up and all is OK ...

Graham

Ummm
So that works for you and I can understand why, but there will be people whom you have lost just by saying your headlamps are powered directly from the 2nd Alternator Terminal. They would have no idea how to wire that up.
From past experience on this Forum, Posts can be read in years to come and some people have so little knowledge in one or more areas, they just readily assume that what they see can be taken as Gospel.

Whilst you may know what you're doing, there's people reading these Forums that think an 'Ohm' is the sound a Buddhist Monk makes when chanting.

[LaughingBoy]

You make good points.

In case anyone is interested here is a good guide on how to wire up headlights via relays -

http://www.danielsternlighting.com/tech ... elays.html

Graham

[oliver90owner]

how thick a wire?

There is a misconception that you automatically need a cable to match the alternator's rated output - so e.g. if you had a 18 ACR 45 AMP alternator then you'd need a cable capable of handling 45 amps. This is not the case. An alternator will only output what is demanded of it. On a Minor with standard electrical equipment the load with headlights, heater and wipers all turned ON, the electrical load is less than 20 amps. The standard wiring should be sufficient. The original Minor dynamo put out a maximum of 22 amps.

So the size of the cable is dependent on the maximum electrical load NOT the alternator's potential output. If you have extra circuits e.g. a heated rear window and electric cooling fan then you could run a thicker cable. An excellent alternative option is to run the headlights directly from the second alternator output terminal via relays. This keeps a big chunk of current (about 10 AMPS) completely separate from the alternator/solenoid cable. There are other advantages too - less voltage drop for the lights and there is no current running through the dashboard headlight switch.

Graham

Every cable should match the maximum load possible. For a 45A alternator, a conductor capable of passing that current must be used to avoid potentially melting the insulation and possibly causing a fire. There is no excuse for recommending anything else, particularly if it could cause a disaster as above.