Irony
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| posted on 9/11/15 at 11:11 AM |
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Alternator not working
Broke down again last night. 2nd time now in 100 miles. Turns out my alternator is not charging the battery. In fact I don't think it's
working at all. I doubt it's the alternator as it's new. I doubt its my wiring as its so simple but I think it may be the warning lamp.
I have read that the warning lamp needs to be at least 2 watt to activate the alternator. I have stupidly wired in a LED warning lamp that I think is
0.5watt. I don't really want to unwire the dash and change my warning light cluster. Can I just wire in a inline bulb in the engine bay
somewhere so both will light up and hopefully activate the alternator?
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Irony
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| posted on 9/11/15 at 11:12 AM |
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Or even a resistor in the wiring??
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theconrodkid
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| posted on 9/11/15 at 11:48 AM |
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either will work,a bulb would be easier as you know the value 
who cares who wins
pass the pork pies
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britishtrident
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| posted on 9/11/15 at 12:12 PM |
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It might be an idea to wiring in a voltmeter, then at least you will know if is charging..
[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]
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40inches
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| posted on 9/11/15 at 12:19 PM |
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quote:
Originally posted by britishtrident
It might be an idea to wiring in a voltmeter, then at least you will know if is charging..
Essential IMO
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gremlin1234
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| posted on 9/11/15 at 12:40 PM |
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quote:
Originally posted by Irony
Broke down again last night. 2nd time now in 100 miles. Turns out my alternator is not charging the battery. In fact I don't think it's
working at all. I doubt it's the alternator as it's new. I doubt its my wiring as its so simple but I think it may be the warning lamp.
I have read that the warning lamp needs to be at least 2 watt to activate the alternator. I have stupidly wired in a LED warning lamp that I think is
0.5watt. I don't really want to unwire the dash and change my warning light cluster. Can I just wire in a inline bulb in the engine bay
somewhere so both will light up and hopefully activate the alternator?
simple answer, Yes.
if using a resistor it will need to be at least 2W rating.
note the new bulb should not be 'inline' with the dash one, but parallel
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johnemms
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| posted on 9/11/15 at 12:50 PM |
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My alternator stopped when the LED bulb packed in..
I took the LED out of the fitting and replaced it with a regular 12v bulb - sorted.
[Edited on 9/11/15 by johnemms]
Own chassis & Build - First time pass!!
"7's" aren't really "cars", they are 'experiences"
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Irony
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| posted on 9/11/15 at 01:06 PM |
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quote:
Originally posted by britishtrident
It might be an idea to wiring in a voltmeter, then at least you will know if is charging..
Forgive my lack of electrical knowledge but I have voltmeter wired in. It displays 12v normally. I assumed that when the engine was running the
alternator would output at 12v so there would be no change in the gauge. It's a big battery so when the lights etc come on there is little
change in the gauge. What is 'normal' activity on a voltmeter dial then? I have never built a car before so I don't know what to
expect.
quote:
Originally posted by gremlin1234
simple answer, Yes.
if using a resistor it will need to be at least 2W rating.
note the new bulb should not be 'inline' with the dash one, but parallel
Can you explain this, why will wiring them up in series not work?
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adithorp
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| posted on 9/11/15 at 01:12 PM |
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You should be seeing around 14v when running. If it's just 12v then it's nt charging.
"A witty saying proves nothing" Voltaire
http://jpsc.org.uk/forum/
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gremlin1234
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| posted on 9/11/15 at 01:23 PM |
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quote:
Originally posted by Irony
Can you explain this, why will wiring them up in series not work?
because the led will limit the current flow. - the led would light brightly,
and the bulb just glow gently.
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BenB
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| posted on 9/11/15 at 03:10 PM |
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As has been said you want 13.5-14v across the battery when charging. An LED just won't flow enough current to excite the coils in the alternator
to get the power produced. Different alternators require different amounts of oomph to get going- the alternator on my bike needs a whole load- a big
arse bulb was required to get it to work, anything with too much resistance (IE less current) and it would stop.
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Irony
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| posted on 9/11/15 at 04:10 PM |
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Found some info on my Austin Metro Alternator online and it requires a 2watt bulb. I shall have to go out and find a 2watt 12v bulb and a bulb holder
to wire in to the system,in series with the existing LED warning light! I wonder where I'll find those?
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rusty nuts
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| posted on 9/11/15 at 04:38 PM |
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Metro? Or what wattage bulb is fitted to the little universal warning lights you can get from motor accessory shops ,motor factors or caravan shops?
Suspect one would be perfect?
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BenB
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| posted on 9/11/15 at 04:45 PM |
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You can always parallel them up to get more amps if necessary.
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Irony
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| posted on 9/11/15 at 04:54 PM |
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I have a broken speedo at home and that comes with 2 bulb holders and two 2 watt bulbs. They would be easy enough to wire in and I have them. Job
done. Thanks fellas!
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gremlin1234
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| posted on 9/11/15 at 05:26 PM |
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quote:
Originally posted by Irony
Found some info on my Austin Metro Alternator online and it requires a 2watt bulb. I shall have to go out and find a 2watt 12v bulb and a bulb holder
to wire in to the system,in series with the existing LED warning light! I wonder where I'll find those?
in parallel, not
series.
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britishtrident
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| posted on 9/11/15 at 05:54 PM |
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Not series that will reduce the excitation even more.
[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]
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britishtrident
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| posted on 9/11/15 at 06:22 PM |
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For the non-electrotechnic people those little pen style LED alternator testers are great and they only cost buttons.
NIKKAI Battery and Alternator tester
BATTERY ALTERNATOR TESTER INDICATOR 12 VOLTS CAR VAN LED INDICATORS PROBE TEST
[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]
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JoelP
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| posted on 10/11/15 at 10:19 PM |
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This thread has solved my problem tonight too, so thanks! I had no bulb initially and the engine wouldn't turn off, added a little bulb and it
stopped charging, read this thread, cut the indicator bulb off my van, job done. Cheers!
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BenB
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| posted on 10/11/15 at 10:32 PM |
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I got a little voltmeter off eBay for debugging issues like this. Plugs into the lighter socket and does the job nicely. Also of course shows
whether I'm using more amps than I'm making....
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britishtrident
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| posted on 17/11/15 at 07:55 PM |
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This ScannerDanner Youtube video is a good walk through on exactly this topic https://www.youtube.com/watch?v=--AdY8z1QfU
[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]
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02GF74
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| posted on 17/11/15 at 08:47 PM |
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quote:
Originally posted by BenB
I got a little voltmeter off eBay for debugging issues like this. Plugs into the lighter socket and does the job nicely. Also of course shows
whether I'm using more amps than I'm making....
Why ofcourse? Lighter socket is connected across battery so your plug device can only show battery voktagr.
To see amps produced or drawn would require a shunt in series with the battery, so i dont believe your plug in gizmo van do that. :p
Bugger me its windy outside 
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britishtrident
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| posted on 17/11/15 at 11:06 PM |
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Those cheap simple plug in voltmeter are invaluable Voltage across the battery is most important measure, anything over 12.9 volts running and the
alternator is just meeting the loads on it, over 13.4 volts under load and there is enough amps going into the battery to replace the energy taken
out by even a very cold start in less than 20 minutes running. Over 15 volts and battery is getting over charged, which will shorten the life of the
battery and every electrical item on the car.
They can do other valuable tests the cold cranking voltage test gives a valuable early warning that the battery is on its' way to Boot Hill,
basically if the voltage drops below 10.1 volts when cold starting the battery will let go in a cold snap. This test isn't as good as testing
with a modern battery impedance smart tester but it is simple and easy.
The charge decay test is also handy simply after stopping the engine, turn the lights on for 1 minute to take the surface charge off the battery
plates , then turn the lights off and note the voltage, after 20 minutes check voltage if the difference between the readings drops excessively the
battery is on the way out.
It depends on temperature good battery should show 12.5 to 12.8 volts with engine off and no electrical loads when fully charged.
These checks are simple they won't show current, current ripple or voltage ripple, voltage spikes, or battery charge capacity but they are a
valuable guide.
These days shunt ammeters aren't used for charging and starting system testing, the tools of choice are DC current clamps will show charging
rate and when used with oscilloscope show the AC current ripple and spikes. The simplest way to check alternator voltage ripple is to connect a a
DMM on an AC voltage scale directly to the B+ terminal of the alternator.
[Edited on 17/11/15 by britishtrident]
[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]
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Irony
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| posted on 18/11/15 at 03:57 AM |
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Thanks for all the replies guys. I have got it sorted now. Turns out the problem was me. I think i must have been drunk when I wired the alternator
circuit up. Either that or I didn't understand it and blindly followed the premade looms tell rate labels. The energiser cable wasn't
connected to 12v+. I'd connected it to earth.
Anyway I also bought a battery tester like in the links above.
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02GF74
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| posted on 18/11/15 at 02:51 PM |
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quote:
Originally posted by Irony
Turns out my alternator is not charging the battery. In fact I don't think it's working at all. I doubt it's the alternator as
it's new. I doubt its my wiring as its so simple  but I think it may
be the warning lamp.
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