Right as ever im after some advice,

Since ive restod my saph ive been having alternator issues, before i used to get 14v at the ecu,

After putting the car back together i noticed this had dropped down to 13.5 i put this down to having painted/powder coating everthing n ruining good earths

but the more i drove the car the more the voltage strated dropping, now reading all the horror storries about what low voltages can cause i took action n bought another alternator(second hand but was working fine when taken out of the car)

probblem is this alternator is showing identical issues! even down to producing the same voltage at the ecu,


So before i bite the bullet n buy a new alternator from burton power is there anything else that could be causing this powwer drop??

like break down of wires due to heat from the turbo??

Any suggestions welcome cheers jay

 

Jay, could it be the voltage reg on the Alternator and the Alternator itself??

 

i thought that bud but to have identical issues from to different alternators and regultors its strange

 

Check the charging circuit, including the contacts on the lamp inside the instrument panel

I had all kinds of electrical gremlins that appeared to be alternator-related, I even swapped alternators as you describe.

This solved my problem

Neil.

 

will do fela

 

I changed mine for another second hand one when I first rebuilt it... same problem so took it for a recon and problem solved thankfully.

 

Jay check the main wire from the alternator to the battery(runs on chassis leg under turbo) as this will probably be green/corroded.
If you have a multimeter check the continuity from the alternator connection to the battery positive terminal.

 

Cheers rich i was thinking this could be te issue as like a tool ive not been running a heat shield!!

i may re-wire the charge circuit just to be on the safe side?

 

Yeah i just run a new wire direct from alternator to battery. Taped up old wire ends and left in place.

You could run a temporary wire using a 'jump lead' just to check

 

13.5 volts is fine on a 12volt system why worry?

 

Nice just out of interest what gauge n type of wire did you use??

good thinking with the jump leads as well cheers

 

I used battery cable from Vehicle Wiring Products.

 

because thats just on idle with out any darin like light/s fans etc, i have seen the voltage drop to 12.5 n the bat light flicker!

also low voltage aint good when hard on boost, the fuel pump dont like it!

have a read of stus articals

http://www.motorsport-developments.c...AF257.tech.pdf

 

as ever your a font of information cheers fella

 

Jesus battery cable, that is so seriously not needed, a 90 amp alt will put out continuously around 40 amps if it's a good one, the 90 is a peak for a split second.
Some much thinner wire such as 56/030 is more than up to it, 76p a metre from
vehiclewiringproducts.co.uk this is thinwall which will be much better with the heat of under bonnets also, this carries 39 amps continuously and is similar to what I've used, I used 2X 28/030.
If you use gold plated terminals on the wire this would be even better.
tabetha

 

Dose it go below 12v? if it has 12v its fine what dose it have at the fuel pump when u switch a few things on. If its a 12v fuel pump and a 12v ecu then 12v is all it needs! And when u say it drops when u turn things on dose it rise when u rev it?

 

I'm sorry but for once you are wrong.
A 90 Amp alternator will do 80 Amp all day long and will peak at over 100 Amp. It will not deliver 100 Amp for a very long time but an hour won't be problem. I repair alternators and starters for a living so couldn't resist replying.

 

Very unlikley in the confines and heat of a cossie engine bay being cooked right next to the turbo, bit different to on a test rig in a nice cool workshop, I test all mine at the place where I repair them also, if I'm feeling lazy I let the lads do it.
As you know the more they output the faster they wear my example was based on a average expected use go drawing even 90 from a 90 alt and it aint going to last long, in use I always say ideally for long life alt needs to be around three times capacity that you regularly draw, not to be on limited time.
tabetha

 

13.5V is fine but it should not be dropping under 13V under load, the battery light coming on to me would indicate that the alternator can not cope with the draw. I would check the engine earth strap along with additional earth points first and if not the alternator. I assume as you have replaced alternator once, regulator can be ruled out unless you used one from old one and was alternator new or second hand?

Martin

 

Oh, and check the fusible links by the live terminal on the battery. I had issues here a while ago

 

Thakns for all the helpful replys!!!

well ive just nipped out to the garage n check/rechecked all the earths, All seam fine so moved on to a jump lead direct from the alternater to the battery as suggested by rich!

And problem solved ish ha!!

on idle im getting 14.0v at the ecu!! with lights on 13.7 and lights + fans on 13.4!!

i cant see what happens under load but i think its safe to say that due to me being a twat not running a heat shield had cooked the charge wire!!!!!

I will say though im thinking of haveing the alternator refurbished as well just for the belts and braces approach!!!

chees jay

 

At least you have found the fault.Reading this makes me wanna check my battery/alternator charge.

 

Great stuff!

 

Why ? You know the output is OK with a good wire.

The standard wire is 6.0mm^2 in size if you're going to buy new. This size will be fine, unless you're running with a higher rev limit than standard, in which case slightly bigger would be better.

 

1 x 56/030 is rated at 39A

2 x 28/030 together are rated at 50A, the same as the standard alternator wire.

 

cheers fella