Alternator wiring

topcatcustom · Post by **topcatcustom** » Sat Nov 21, 2009 8:08 pm

The mx5 loom has a main power lead for the alternator which is obvious- and there are 2 other leads on a 2 pin plug. The Ford Duratec alternator I'm using has the main power stud on the back, and a 3 pin socket on the side. How do I know what pins I need to use?!

ChrisJC · Post by **ChrisJC** » Mon Nov 23, 2009 8:33 am

Are there any markings on the case near the connectors that label the wires?

Connections are likely to be:
- Warning light
- Tacho feed

Might be a bit of detective work to find out which is which. In fact, I might try powering the system up, and experimenting with the warning light to see if it lights up on any of the terminals.

Chris.

topcatcustom · Post by **topcatcustom** » Mon Nov 23, 2009 9:23 am

No markings, so maybe I could put power to the main stud and see which are live and go from there? The 3 pins are tiny, and the 2 pin plug on the mx5 loom has much bigger connectors with average size cable, there is a guy who I have used a few times before who repairs them and runs them on a test bed who is very knowledgeable, maybe I should take it over and ask him!

ChrisJC · Post by **ChrisJC** » Mon Nov 23, 2009 9:48 am

topcatproduction wrote:there is a guy who I have used a few times before who repairs them and runs them on a test bed who is very knowledgeable, maybe I should take it over and ask him!

Now that sounds like a good plan!

Oh for the old days when everything had a Lucas alternator.

Chris.

topcatcustom · Post by **topcatcustom** » Mon Nov 23, 2009 9:49 am

ChrisJC wrote:
topcatproduction wrote:there is a guy who I have used a few times before who repairs them and runs them on a test bed who is very knowledgeable, maybe I should take it over and ask him!
Now that sounds like a good plan!

Oh for the old days when everything had a Lucas alternator.

Chris.

Yea, this would have had one too if they were short enough to fit in the gap!!!

topcatcustom · Post by **topcatcustom** » Wed Dec 02, 2009 5:40 pm

went to the alternator man and found out it is a stupid electronic type that communicates both ways with the ECU and delivers exactly what is needed- wont deliver a single volt unless its talking to its stupid computer friend!!!

On the search again now, need one with a body under 130mm long...

topcatcustom · Post by **topcatcustom** » Mon Dec 14, 2009 12:35 pm

To save making another thread- I think I found a new mini classic alternator that measures in just short enough- but it is 45A. Is it enough?! I know on paper it probably just is but is it like some manufacturers power claims- i.e. vastly over stated or are they pretty good?

Apart from the (1990's) headlights and tail lights, the only things electrical are the heater fan (car wont be used in winter and is a soft top in summer!), ignition, fuel pump (2-3A?), rad fan (7-8A?) and my vacuum pump which wont be used all the time. (maybe 10A or something...)

I will put a fairly big battery in the boot, if the 45A alt will be ok I'll buy it and job done, if not I'm going to have to find a new tiny Denso one or something which means more £££

ChrisJC · Post by **ChrisJC** » Mon Dec 14, 2009 1:10 pm

Hmm.
Full set of lights = 15A
Twin electrics fans = 15A

I expect fuel + ignition to be 10A

Heater, wipers etc

I think you'll be fine in the summer, and pass MOT's, but winter driving in traffic you'll be knackered and run the battery down in no time.

Chris.

topcatcustom · Post by **topcatcustom** » Mon Dec 14, 2009 1:12 pm

Oh yea- and wipers! Well its not going to be going out in the winter unless its a nice dry warm day and tbh I cant see doing a lot of night driving but you never know! Maybe I'll try for a 55A version if there is any about.

Ian Anderson · Post by **Ian Anderson** » Mon Dec 14, 2009 1:19 pm

I'm amazed at how it all adds up

I have a rangie battery - 70 amp hour thing
But in the GT40
2 fuel pumps - low perssure to feed the swirl and then HP feeding injection
(8 amps each)
Ecu 8 Amps
Lights 130watts total - 11 amps
Dash lights 45 watts (You'd be surprised how many damned bulbs there are)
2 rad fans at about 12 amp each
Wipers
Indicators
Fresh air blowers 4 at 5 amps

That's before I turn on the 2 x 150 wat spot lights

During the day the Volt meter reads 14.somethig volts
Damp night lucky to read 12.5volts

And it's a rangie Alternator I'm running

Hard working and short length go for Diahatsu alternator

Ian

jwriyadh · Post by **jwriyadh** » Fri Dec 25, 2009 6:32 pm

Since the physical size of your Duratec alternator is correct and most likely of ample capacity why not use the Duratec with a replacement external regulator?
Have done this with Lucas ACRs where we couldn't get the standard regulator but had available an external regulator unit from a Dodge Ram.

jw

topcatcustom · Post by **topcatcustom** » Tue Feb 09, 2010 9:56 am

Does anyone know if this will be a normal sort of one or one of the stupid "intelligent" ones?! Perfect size and ends in a couple of hours, the fact its off an aston and 2008 leads me to believe it will probably be another no go-er, but not sure!
http://cgi.ebay.co.uk/ws/eBayISAPI.dll? ... 0432219699

topcatcustom · Post by **topcatcustom** » Tue Mar 16, 2010 9:00 am

New alternator! Denso one from a Rover, it has a main live stud, and a round plug on the back with 4 spades in it laid out a bit like this:

As the engine isn't running yet I cant test voltages on them to find out which is which- but need to wire it up... How do I know what goes where?