9 replies to this topic

[daenesh]

hhey guys so im going to attach a picture of my alternator below and im wondering that since mine has the 3 wires connected from the alternator to the solenoid.. would it be okay for me to connect a thick wire from the left nut which is positive to the solenoid for better connection and flow of electricity?the nut on the right which is covered by that black plastic is the negative which i would then connect to the body.. i did test both big nuts on the alternator with a multimeter to determine which was negative and positive.. any thoughts on this?

Edited by daenesh, 18 April 2013 - 09:35 AM.

[lrostoke]

yes that will be fine..

No need for an extra earth cable though, already earthed through the casing

[Dan]

The covered nut is a single phase AC positive output (W terminal). The entire alternator body is the earth. DO NOT try to earth any of the terminals on your alternator or you may end up with the car on fire. A127 units are generally only equipped with an earth terminal when they are assembled for marine engines as they then have an isolated casing. When fitted, the earth is on the other side of the 3 pin plug. If it was an earth, it would not come from the factory insulated.

The plug output is fine for A127 units up to 80A output. The stud terminal is used for higher power units. Until recently the casings had either one connection set or the other, but not both. If you don't want to replace the original cables into the plug terminals though adding an additional cable to the stud in this way would work fine.

Edited by Dan, 18 April 2013 - 10:17 AM.

[daenesh]

Thanks guys.. Actually there used to be two black covers but one fell off..

[Dan]

Yes both of the positive stud terminals will often be capped. If you end up not using it, it is very sensible to cap the stud and even if you do use it you should get hold of a terminal insulating cover. If you leave it open but connected to the battery, and then knock it with a spanner or something while working on the car you will get a lovely splash. You can cut a spanner in half with a battery splash (my dad tells me that when he was an aircraft apprentice people used to vaporise spanners completely on large batteries), this wouldn't be as bad but would still be exciting.

[daenesh]

haha i absolutely get what you mean.. yeah ill try and get a cover for it.. my belt was loose as well and i tightened it but still no luck.. with the air cond off the volts are at 13.8 which is amazing but once i switch it on it drops all the way to 12volts.. i guess i really have to change the alternator..

[Dan]

The AC system shouldn't really be using all that much electrical power. The clutch should be about 3 - 4 amps, the blower inside the car probably about 8 once it's up to speed and the one for the condenser is presumably not running all the time anyway. The controls won't use much. The reason it is hitting the alternator output may be more to do with the reduced idle speed and so you might get good results from changing the pulley sizes to pick the alternator speed up a little. How much stuff is on with the volts at 13.8? Have you measured the increase in current with the AC on?

[daenesh]

well i am using a small pulley and get max output at 1.4-1.5k rpm.. also with the 13.8 i have my electric fuel pump on, auxiliary fan which is 80watts, and i guess thats about it.. then i switch on the AC and bam it drops to 12.5V even if i rev it doesnt move much..how do i got about measuring the current with the AC on?

[Dan]

Use a clamp meter on the battery cable. I wouldn't try it with a normal meter as you will have to start the car with the meter in place really.

[daenesh]

yeah ive done that but with no luck as well.. i have an old nissan hitachi alternator which is about 80amps it surprisingly fits my brackets.. all i have to do is remove the pulley and use my old one as its smaller and longer.. doing that tomorrow.. then i will try and see if i can get it to work.. theres only 2 wires the thin one and a thick one so im assuming the thick one is positive(+) and the thin wire is connected to the light in the dash meters.. to tell if its charging or not.. i hope it works out if not ill have to go out and buy a new one which is really just a reconditioned one.. heres wad the 80amps alternator looks like..it was taken from a nissan sunny and was used in my friends mini till he changed to and injection engine..

Edited by daenesh, 19 April 2013 - 12:26 PM.