altenator question...

[dabill]

hallo,

recently i purchased a second hand altenator from a guy near sheffield.

mine was starting to die, the bearing had gone and it made a horrible noice at certain speeds... so i got the new one, and since, i have a had a couple of days when i've come back to the car after work, and the battery was dead...

so i've taken the car for a altenator and battery test, and the fella said the altenator was supplying the battery with voltage, but not 14v, only 13and a little bit... would this lead to the battery goin flat over a few days?

its a mk2 8valve digi...91 plate.

also, how much roughly are new altenators, and which one would i need if i do buy one?

cheers

rob

[dabill]

just been looking on the GSF website, and looks like the altenator for a 8v digi is a 90 amp one, however the k-jet is only 65 amp.. is that correct, and if so, could this be the cause of my problem?

[clipperjay]

You can run a 90amp alternator it makes no difference. The volatage regulator will impead the voltage as it see's fit. So it could be another faulty alternator?
1) get a muti meter and check for 13.8V-14.3V from idle to 2k reving.
2) If below 13V alternator bushes or regulator is finished.
3) Cheaper route is to get it over halled could cost £40-£50.
4) Take the postive lead off the battery, then connect the meter and see what amps are being drawn it should be like 0.6 if an interior light comes on when the boot or door is open. This is normal and would take a few weeks to kill a battery without starting. 
5) Could be simply bad battery?
Hope that helps chap!
Jay

[DarnPB]

just been looking on the GSF website, and looks like the altenator for a 8v digi is a 90 amp one, however the k-jet is only 65 amp.. is that correct, and if so, could this be the cause of my problem?

The reason for different amperage alternators is dependant on the equipment the car has. The higher the amperage, the more sevices you can run as well as maintaining the battery.
The battery is there purely to start the car and in case of alternator failure, as an emergency electrical power back-up. The rest of the time, the electrical power source is the alternator.
The battery has 6 cells of about 2.2volts per cell, connected in series. Therefore, the average condition battery at full charge is about 13volts. Therefore, if the alternator is producing less voltage than the battery has, the battery will slowly discharge.
If you have an elaborate ICE system installed, it is advisable to upgrade the alternator to a higher amperage run the ICE.

[dabill]

the old altenator was working fine except it had dodgy bearings, so the battery never went flat. think i will see how i go this week, and if it dies again, i'll swop back to the old altenator, if it still dies, then i know its not the altenator, possibly the regultor. plus i'll purchase a multimeter(if i dont already own one) and have a good poke about...

thanks for advice chaps!

rob