Lotus Elan

Alternator wiring confusion.

PostPost by: wojeepster » Sat Feb 24, 2007 1:29 am

if ammeter burns out everything stops because all current passes through the ammeter (in series). this is not the case with a voltmeter because it is wired in parrallel. I think it is cool that you can peg your ammeter but I wonder if that will continue. Maybe it will. I think I would opt for voltmeter. Ammeter gives better info (like how much it is charging) but alas they don't make big ones.
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PostPost by: iain.hamlton » Sat Feb 24, 2007 6:31 am

Agree that a voltmeter or 60 ammeter is a better way to go, because once a 30 amp meter is pegged, you dont know whether the circuit is pulling 30 or 100 Amps, and the wiring may not be up to it. Remember the original wires were designed for 22 Amps, and even the Lucar spades (in theory) only for 35A. Further, the circuit to the Ammeter brings all that current into tinder-dry environment behind the dash.

Sorry to be alarmist. Dont panic.

On my car the ammeter only measured the current charging the battery not running the lights etc. So next time the meter goes to full scale, switch the lights etc on. If the alternator is only producing 40 amps or something, you may get the ammeter back on the scale, and once that has happened, everything is OK. Alternatively, charge the battery before using the car. In the long term, it makes sense to uprate the meter and wiring.

good luck. let us know how you get on.
best regards, iain
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PostPost by: garyeanderson » Sat Feb 24, 2007 10:30 am

I have been following this thread a little. I think the only wire in question is the 12 gauge brown/yellow that comes from the generator and is tied to the brown 12 gauge wire on the solinoid in an alternator conversion. According to the research I have done this morning, my alternator conversion is undersized and I should address this as soon as possible.
Take a look at the following document
http://www.britishwiring.com/CAT00_35.PDF
see page 2 for wire sizes and capacities. According to this table those 12 gauge wire is good for 25.5 amps and should be 10 gauge for a 35 amp alternator or probably an 8 or 6 gauge for 60 amp (though it doesn't say the exact U.S. spec).

http://www.geocities.com/smithmonte/Aut ... pgrade.htm
More info on aternator upgrade in a U.S. made Mustang and they start
with a 65 amp alternator.

running all that upgraded current behind the dash to an amp meter with all the other wires there is just waiting for the smoke to run out...

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PostPost by: Frank Howard » Sat Feb 24, 2007 7:30 pm

iain.hamlton wrote:Remember the original wires were designed for 22 Amps, and even the Lucar spades (in theory) only for 35A. Further, the circuit to the Ammeter brings all that current into tinder-dry environment behind the dash.

My Europa came from the factory with the Lucas 35 amp alternator. I realize it may put out less than the Mitsubitshi (Mazda 323) alternator.

The Mazda book says it puts out 65 amps at 3,000 rpm with the hi beams and heater fan on. I'm not sure I'm comparing apples to apples because the Lucas rating says nothing about rpm or having the hi beams and heater fan on. Could it be almost twice as powerful as the Lucas unit?

Anyway, despite having a 35 amp alternator, the Europa came from the factory equipped with a Smiths 30 amp ammeter which of course is mounted in the "tinder-dry environment behind the dash" at least when the rain isn't leaking in.
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PostPost by: msd1107 » Sun Feb 25, 2007 1:07 am

There is more choice than either 30 or 60 amp meters. Granted, you can probably live with a 30 amp meter if you use a 35 or 44 amp alternator. Unless you are running some killer audio system, the smallest alternator will be sufficient. Remember, the failing of the generator is that it does not reach maximum charging until 3000+ rpm and you need all those amps while stopped in traffic with headlights on, radiator fan blowing, and have to use the windows.

Although they do not appear regularly, Ebay has had 35 amp meters. And you can get Lucas meters in 50 amp sizes.

As to the debate on volt meter vs amp meter, if you are paranoid enough, both should be fitted. The amp meter shows how much the circuit is charging or discharging. The volt meter shows the battery voltage. A failing battery will show up on the volt meter whereas the amp meter will merrily register a positive charging rate.

Unless you adapt the radio blanking plate to hold the gauges, you could have Prestige make you a new dash and place the instrumants in the best location.

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PostPost by: hatman » Wed Feb 28, 2007 9:10 am

Still dithering, I regret to say. My dither-inducing thinking goes thus:-

If I ignore the 'how to instal an alternator' screed in the workshop manual and, instead, connect the output and field wires to the solenoid, with the warning-light wire connected to the, er, warning light wire and leave the control box where it is, will the lighting circuitry (connected to the large terminal at the bottom of the regulator box) still operate, assuming that the brown live feed from the solenoid on the second lowest regulator connection point is also left in place?

Incidentally, the manual's alternator re-wiring screed refers to a brown/white cable in the main harness. There's no such wire on my S4 nor, as far as I can see, any brown/white wire in the wiring diagrams in the back of the manual. Confused? Yes - that'll be me.
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PostPost by: iain.hamlton » Wed Feb 28, 2007 11:43 am

Howard,

I know they're not about lotuses but suggest you look here:
http://www.mossmotors.com/graphics/prod ... 078MGA.pdf
and here:
http://mgaguru.com/mgtech/electric/ac101.htm


best regards, iain
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PostPost by: triumphelan » Wed Feb 28, 2007 3:26 pm

I removed the ash tray ,made a ally plate that screwed onto existing ash tray holes [so I could replace the ash tray if needed]and fitted an amp meter onto it
Regards John 1969S4DHC
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PostPost by: milestricks » Fri May 06, 2011 1:49 am

ive got the same confusion like yours before then i my brother helped me figure things out then he suggested that i should buy a new alternator repair kit that made my install more appropriate for the elan.
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PostPost by: FOX5D » Fri May 06, 2011 9:26 pm

I've just successfully converted my S3 to an alternator and about to do the same to my S4.

Brian Buckland's article in Issue 1 (Jan ) of the 2010 Club Lotus mag was very hepful.

Jim
Always grateful for advice.
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PostPost by: lotusS2guy » Sat May 07, 2011 7:48 pm

Do you have a link to Brian's article?
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PostPost by: Galwaylotus » Sat May 07, 2011 7:51 pm

The wiring is only going to draw the current based on the loads (lights, heater, etc.) which should not be different whether a dynamo, low amp alternator, or high amp alternator is used. The only time the current should get much higher is if there is additional loads on the circuit or the battery has run down and the alternator is working har toi recharge it - again less likely to happen with an alternator that's providing adeqyate charge current. By the same token, a 65 Amp alternator is a waste unless additional loads have been added to the electrical system. 35 or 40 amps should be sufficient unless major electrical changes have been made - or there is a short circuit! :shock: :wink: :lol:
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PostPost by: Frank Howard » Sun May 08, 2011 12:39 am

Galwaylotus wrote:35 or 40 amps should be sufficient

And that compares very favorably to the 22 amps that the stock Lucas generator puts out. The trouble is, it is difficult to find an alternator that puts out less than 45 amps unless or course, you look to Lucas.
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PostPost by: Galwaylotus » Sun May 08, 2011 4:13 pm

Fair enough. The system will still only draw the current it needs.
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