Daddylonglegs
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| posted on 13/2/13 at 10:22 PM |
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Charging Issue - Pulsing Charge Light
Well this is a strange one!
The car has been sat idle for a few weeks and after finally sorting out the clutch pedal modification I charged up the battery and started it up. Left
it running for a while whilst pottering about doing other stuff. I noticed that the charge light was dimly lit so I tried revving the engine to put it
out. Instead of going out, the light got brighter, and when I hold the revs at about 3000, the light seems to pulse bright then dim every 2 seconds or
so, regular as a clock??
I put a meter across the battery and with the engine off it reads about 12.6V. When I run the engine the voltage rises and settles at about 14.3V from
2000rpm and over.
Anyone got any ideas as to what could be causing this? I did think the regulator, but the charge voltage seems fine. Is it possibly damp or is it just
Pee'd off because i haven't driven it? 
Cheers all.
It looks like the Midget is winning at the moment......
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theprisioner
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| posted on 13/2/13 at 11:28 PM |
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Had these symptoms on one of my vehicles, it was the regulator. Try turning on everything. Difficult to load it sufficiently in a kit car but
headlights + everythig else should do it. If it does not produce a voltage of 13V at revs equivalent to 30MPH the regulator is faulty.
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britishtrident
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| posted on 14/2/13 at 08:20 AM |
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Sounds like it needs a regulator and or brushes, however check the main connections at the back of the alternator are making a good clean and tight
connection.
An alternator should produce at least 13.4v at any crankshaft speed above idle (say 1500 to 2500 RPM ) with or without normal loads ie
headlamps.
The maximum voltage should not not exceed 14.9 volts and the voltage should not leap upwards when the the headlamps are switched off.
Older and smaller alternators tend to charge about 13.7v , alternators from bigger modern engines usually charge at near the top end of the
voltage scale.
With the engine and everything else switched off after a few minutes rest a reading across the battery of 12.6 to 12.8 volts is normal.
Although it varies a bit with temperature 12.8v indicates a fully charged battery. As temperature approaches zero Centigrade battery voltage
falls off.
[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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Daddylonglegs
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| posted on 14/2/13 at 08:21 AM |
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I was hoping it was not that as the alternator is brand new, only done about 30 miles 
I have tried the lights-on, hazards, brake lights etc. and according to the multimeter it is still pushing above 14V at 2000-25000rpm.
It looks like the Midget is winning at the moment......
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owelly
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| posted on 14/2/13 at 09:19 AM |
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Have you tried disconnecting the flasher relays just to make sure you don't have an earthing fault which is causing the problem. In my
experience, a busted reg usually haa symptoms that relate to engine/alternator speed so as your fault produces a regular pulse....
http://www.ppcmag.co.uk
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splitrivet
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| posted on 14/2/13 at 11:42 AM |
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Sounds like the diodes in the alternator.
Cheers,
Bob
I used to be a Werewolf but I'm alright nowwoooooooooooooo
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Daddylonglegs
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| posted on 14/2/13 at 01:55 PM |
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quote:
Originally posted by owelly
Have you tried disconnecting the flasher relays just to make sure you don't have an earthing fault which is causing the problem. In my
experience, a busted reg usually haa symptoms that relate to engine/alternator speed so as your fault produces a regular pulse....
Perhaps I misled by saying about the flashers etc. The pulsing on and off is independent of lights on or off. It will stay just glowing until I raise
the revs above 2000-2500rpm or so, then it will go bright for maybe 2 secs, and then dim for 1/2 sec, then bright for 2secs etc. All the time it is
doing this, my multimeter seems steady and doesn't change in time with the light changing.
If that makes sense?
It looks like the Midget is winning at the moment......
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britishtrident
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| posted on 14/2/13 at 03:25 PM |
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What make/type of alternator is it I presume it is rebuilt/reconditioned/re-manufactured as opposed to brand new ?
[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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Daddylonglegs
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| posted on 14/2/13 at 04:29 PM |
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It's the Lucas A127-55Amp type. It was a brand new one I got from my local garage. The guy had it lying around in the back.
Linky Do Dah
It looks like the Midget is winning at the moment......
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britishtrident
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| posted on 14/2/13 at 04:39 PM |
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quote:
Originally posted by Daddylonglegs
It's the Lucas A127-55Amp type. It was a brand new one I got from my local garage. The guy had it lying around in the back.
Linky Do Dah
With Lucas alternators always check the condition of the blade connectors, clean the blades on the alternator with a nail board and fit new
Lucar spades if they are old/dirty/slack in any way.
After that I would swap the control regulator/brush box for a new item -- an unbelievably easy job to do and they cost buttons, I am pretty
sure have a known good one one lying around but you will find them on ebay for less than a tenner including P&P. It is more than possible
the regulator pack was swapped before you got the alternator as they are only held on by three hex screws and can usually be swapped without
even removing the alternator from the car.
[Edited on 14/2/13 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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splitrivet
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| posted on 14/2/13 at 05:35 PM |
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I would be surprised if it was the regulator as I say more likely a leaky diode in the rectifier pack. Although the flashing light is a bit wierd.
Might be worth doing a diode test on the pack if you have a DVM. Ive had this in the past (without the flashing light just getting brighter) with an
increase in revs one of the diodes tested duff and a replacement cured it.
Cheers,
Bob
I used to be a Werewolf but I'm alright nowwoooooooooooooo
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Daddylonglegs
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| posted on 14/2/13 at 08:57 PM |
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Cheers chaps! I'll get the DVM on the diode pack and see if they are OK. I don't think the regulator is at fault simply because the
voltage seems pretty consistent with a serviceable alternator.
Jobs for the weekend
It looks like the Midget is winning at the moment......
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britishtrident
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| posted on 14/2/13 at 09:23 PM |
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Rectifier faults are no uncommon on these but normally it shows by flattening the battery in a couple of hours.
[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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Daddylonglegs
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| posted on 14/2/13 at 10:01 PM |
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If I'm being a muppet please say, but I am assuming that the rectum frier must be OK as I'm getting DC and as it's around the
correct voltage I am assuming the regulator is OK. But something is amiss. Maybe I need to chase wiring? I guess it won't hurt to whip the dash
off and check the light connections.
It looks like the Midget is winning at the moment......
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splitrivet
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| posted on 15/2/13 at 12:10 AM |
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Connections are the first thing to check including the engine earth strap which I assume youve done but obviously youve got a circuit otherwise the
light wont light at all.
The regulator does as it says and regulates the voltage,the rectifier has 6 diodes if one of those is leaky it will give your symptoms but I have to
admit the flashing light is strange but it could show one of the diodes is breaking down under load. I'm sure if you google your alternator its
a very common model, it'll tell you how to strip it down and how to do the checks.
If all else fails a visit to the scrappy wont be a big hardship if you succeed youve learnt something new.
Let us know how you get on.
Cheers,
Bob
I used to be a Werewolf but I'm alright nowwoooooooooooooo
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