JoelP
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| posted on 11/11/14 at 08:41 PM |
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Alternator not charging
The alternator in my pinto locost doesn't seem to be charging. I could use some ideas as to what is likely to be wrong, since I've only
got 2 days til a long road trip!
It has two wires in the back of it, one big and one small, which fell off the other day. Would it be obvious if I'd put them on the wrong
terminals? The alternator has 3 spades on the back, one which appears unused. The lad I bought the car off was having trouble with the battery so it
may not be a new problem.
First step tomorrow is to get a good multimeter to actual measure the voltage!
As a silly aside, are there any ingenious ways to keep it charged with needing an alternator?!
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JoelP
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| posted on 11/11/14 at 09:13 PM |
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I should clarify that it might be charging a bit at full revs. I had headlights and fan on and it started to die, either spark or fuel pump, but by
turning everything off a made it last another half hour, though I had to flog the life out of it to stop it stalling. Once I got home though it was so
dead even the hazards wouldn't work.
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Dooey99
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| posted on 11/11/14 at 09:14 PM |
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hello
measure the battery voltage then fire the car up and measure the battery voltage when the car is running the battery voltage should be between 13.7
and 14.4 volts whn the engine is running, if the voltage does not increase at all when the car is running then you should stop the engine and check
the continuity between the big wire which is the main feed which supplies power from the alternator to the battery if the continuity is good then
check the continuity for the small wire, the small wire is most likely the one that supplied the alternator with its 'start up current' as
alternators need a tiny bit of electricity to kick into life, which is earthed through the alternaor its self. this will also run through the battery
light on your dash board, im not entirely sure how it will be wired but i imagine it will have a positive ignition switched feed going to the battery
light then to the alternator. check all these wires, sounds like abit of a drag but might be worth it if you find a break in the wire or a bad
connection. once the alternator is spinning it cuts earth from the ignition so the light no longer has a complete circuit so goes out. alternatively
turn the ignition on and check the terminal where the small wire goes on the alternator has a battery voltage (12v) this will do the same thing as
checking all the little wires individually. then disconnect the little wire from the alternator and see if the light goes out the earth it out and see
if it comes on 
if all this makes no difference then the third terminal on the alternator may need to be used, do you have a photo of the back of the three terminals
on the back of the alternator?
i love automotive wiring as strange as that sounds :/
Less weight more speed, more power more speed
If in doubt, give it a clout
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JoelP
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| posted on 11/11/14 at 09:44 PM |
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Cheers mate, that's exactly what I need! The bolt on the bottom of the alternator had fallen out the other day, and whilst I fixed it all the
terminals fell off. The little wire goes to a little termina, the big wire to a big terminal that is one of a pair of big ones. When I put the big
wire momentarily onto the wrong terminal, it sparked, despite the engine being off, so I'd imagine the other big terminal is earthed one way or
another.
I'm not too good with uploading photos from my phone as it usually says wrong format, but I'll have a stab tomorrow!
Cheers.
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Dooey99
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| posted on 11/11/14 at 09:56 PM |
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okay mate let me know how you get on...
sometimes there are two big terminals on the alternator and they are both positive, this is probably not the case with yours as it sparked or it is
the case and the internals are broken and are earthing out when they shouldnt be.
ive always thought my explanations of things are shite but hopefully its understandable
Less weight more speed, more power more speed
If in doubt, give it a clout
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snowy2
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| posted on 12/11/14 at 07:40 AM |
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If your small wire fell off the other day there is a real possibility that you have killed the regulator....in which case its a new alternator.
sometimes you are the pigeon, most of the time the statue.
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r1_pete
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| posted on 12/11/14 at 07:56 AM |
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quote:
Originally posted by JoelP
I'm not too good with uploading photos from my phone as it usually says wrong format, but I'll have a stab tomorrow!
Cheers.
Open the photos and then save them as jpeg / jpg format.
What type of alternator do you have, from the description two big and one little spade, it sounds like one of the Lucas ACR range, in which case the
two large spades are common, are you sure you didn't catch the connector on the alternator body?
What does the warning light do?
It does sound like the regulator / rectifier is dead, which can result in one of two problems 1. no charge, 2. Overcharging which very quickly ruins
the battery. A multimeter across the battery terminals will soon tell you which as described above.
ACR Alternator wiring is straightforward, the big terminal goes direct to the battery, and the small one the opposite side of the ignition light to
the switched live.
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JoelP
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| posted on 12/11/14 at 09:31 AM |
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I should clarify that the engine wasn't running when the wires came off, so hopefully no damage from that. I've just bought a meter and
will hopefully get some joy tonight.
Plan a is to buy 2 spare batteries and just swap them as they run out!
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JoelP
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| posted on 13/11/14 at 08:08 AM |
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Big wire is fine, little wire seems to do nothing. Would any ignition feed do or does it need to go past the battery warning light?
Cheers!
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jeffw
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| posted on 13/11/14 at 10:48 AM |
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needs to go through a load (typically a lamp) to energise the alternator. If out 12v via a lamp the alternator will not start charging (lamp goes out
when it starts).
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JoelP
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| posted on 14/11/14 at 05:59 AM |
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Forgot to update this thread. Firstly, thanks for all the help. I drove all the way up to Tarbert in Scotland yesterday without it missing a beat.
I wired an energising feed in to the alternator from the only ignition live I could find - the supply to the fuel pump. It's sorted out the
charging nicely, I've got 13.7v at idle, 13.9 with some revs, and turning everything on doesn't drop it much. However, the engine now
doesn't turn off on the key and needs stalling! I'm guessing a (light emitting) diode would sort that?
It was an amazing drive, if a bit wet!
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jeffw
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| posted on 14/11/14 at 06:21 AM |
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You need to move it to an unused switched feed and put it via a lamp.
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