Alternator testing, battery testing

[ibiza_95]

My alternator i believe is broke, but only recently, since when i tried to make it clean ...

is there a check i can do to see if its providing the battery with enough power to charge it. im certain its not but it would be best to check it.

also, is there a way of checking that the battery isnt being drained when its left still. im not sure how to do it but the alternator is the most important here as i have to keep jumping it everytime i want to start it now.

not cool!
Cheers in advance

 

[andyj]

get yourself a voltmeter, start the engine, and measure the voltage across the terminals on the battery.... you should see about 14v if the alternator's working correctly.

 

[ibiza_95]

ok, ive had another look trying to find the problem before i go and replace everything... i need a new alternator. the pulley on the side is spinning but the insides are seized i do believe.

now...

on the hunt

 

[Muttley]

If the alternator were not working, you should see the battery warning light stay lit on the dash. I'd be very surprised if it were seized in such a way that the pulley still turned.

Do the charging test andyj suggested - you will need to get someone to push the accelerator just a little, to get a steady reading, which should be between 12 and 14 volts. It should stay steady even when you switch on all the electrical bits, lights, heater blower, heated windows etc.

If it fails to make a steady voltage above 12 volts, then something is wrong. The first thing to go on alternators is usually brushes - they wear out; next is the voltage regulator. They are underneath the plastic end cap. The Haynes manual tells you how to get to them.

 

[ibiza_95]

i can physically see that the alternator pulley is turning but the internals arent. ive tried WD-40 and a bit of pressure to try and turn the internals but it just wont move.

 

[ScottyDog]

why dont you test the alternator, instead of just replacing it?

 

[Icecavern]

Just measure the voltage at the battery with the engine running. If it's 14v the alternator is fine. You can't see the revolving section normally anyway

 

[ibiza_95]

you can see inside the alternator through the gaps here

and when the pulley is moving this bit isnt.

I hope this bit is supposed to move anyway... just thought it may not lol... tut

alternator is bought now anyway

just picturing a motor in my head... i think ive made a boob

 

[Fl@pper]

those bits are the coils inside

they dont move anyway

 

[ibiza_95]

bugger

apologies to everyone...

oh well, well just have to see if a new alternator will fix it anyway. i may as well test it before i go and fit one.

Cheers guys

 

[Icecavern]

Why didn't you check it before taking it off, 2 minutes could have saved you the cash...

 

[ibiza_95]

i havent taken it off yet, ive just bought another one, not here yet needs delivering. i think it must be that anyway, but ill be sure to check it before i take it off.

i sprayed carb cleaner on it before i went on a road trip, cleaned it v.nicely... didnt work after tho.

 

[Muttley]

Well, carb cleaner is for getting deposits off of carburettor bodies, and is absolutely the wrong thing to be spraying on an alternator. The solvents may have affected the insulation of the coils, or softened the plastic housing for the brushes, jamming them.

That said, I still don't think it is your alternator. The usual reason for needing a jump start is a failed battery. Your local garage, or somewhere like Kwik-Fit, can do a battery test for you.

 

[ibiza_95]

brand new battery.
will try and buy a voltmeter tomorrow and see. i know i shouldnt have done it, but i saw how clean it made the carb and thought ... 'wow' lol

'what else can this baby clean!'

needless to say i wont be doing it again