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?
Or even a resistor in the wiring??
either will work,a bulb would be easier as you know the value
It might be an idea to wiring in a voltmeter, then at least you will know if is charging..
quote:
Originally posted by britishtrident
It might be an idea to wiring in a voltmeter, then at least you will know if is charging..
quote:simple answer, Yes.
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?
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]
quote:
Originally posted by britishtrident
It might be an idea to wiring in a voltmeter, then at least you will know if is charging..
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
You should be seeing around 14v when running. If it's just 12v then it's nt charging.
quote:because the led will limit the current flow. - the led would light brightly, and the bulb just glow gently.
Originally posted by Irony
Can you explain this, why will wiring them up in series not work?
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.
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?
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?
You can always parallel them up to get more amps if necessary.
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!
quote:in parallel, not series.
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?
Not series that will reduce the excitation even more.
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
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!
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....
This ScannerDanner Youtube video is a good walk through on exactly this topic https://www.youtube.com/watch?v=--AdY8z1QfU
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....
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]
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.
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 simplebut I think it may be the warning lamp.
https://www.google.co.uk/search?tbm=isch&hl=en&q=alternator%20wiring#imgrc=QYuic3UZ-Qlu6M%3A
thought it was series so went and checked.