This is the standard bulb used in the 300 at least here not the easiest to wire up though as it is a small wedge bulb and you really need the correct holder for it. Worst case get a 100 ohm resistor and use that in place of the bulb. That should work but obviously it wont act as a charge warning light
Confusing altenator problem
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This one actually (clear not green)
toms3
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would one of these resistors be ok?
http://www.ebay.co.uk/itm/200654817736?_trksid=p2057872.m2749.l2649&ssPageName=STRK:MEBIDX:IT
http://www.ebay.co.uk/itm/200654817736?_trksid=p2057872.m2749.l2649&ssPageName=STRK:MEBIDX:IT
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14.4 to 14.8V @2000rpm. all in the CFAQ section
Not on his car MAD more like 13.8 to 14.2.
Yes they would be fine
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dont tell me - tell AC Delco
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dont tell me - tell AC Delco
His car is a 1987 vehicle from his info, it is doubtful it would have been fitted with a full calcium battery. 14.4 to 14.8 is the modern voltage needed to service those. Would boil a lead acid battery dry in short order.
toms3
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thanks again kwakerman, ill get this temp fix sorted and at least my alternators charging for now. landyzone has been a great help thanks to everyone. ill update when i get to the bottom of the problem.
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depends how you test it - but we are arguing over semantics. the OP will know if the alternator charges or not.His car is a 1987 vehicle from his info, it is doubtful it would have been fitted with a full calcium battery. 14.4 to 14.8 is the modern voltage needed to service those. Would boil a lead acid battery dry in short order.
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Ok but if he has a lead acid battery fitted and it's charging at 14.8 volts he has a problem.
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if he measures it at the battery. but he hasnt said it is charging at 14.8V. Anyway, I was referring to the test procedure in the CFAQ section, which I believe uses a dummy load. Unfortunately the link no longer works, so we will never knowOk but if he has a lead acid battery fitted and it's charging at 14.8 volts he has a problem.
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if he measures it at the battery. but he hasnt said it is charging at 14.8V. Anyway, I was referring to the test procedure in the CFAQ section, which I believe uses a dummy load. Unfortunately the link no longer works, so we will never know
If he has a 1987 vehicle he will get nothing like 14.8 volts from the alternator or shouldn't do. 13.8 was the norm back then. You said what he was looking for was 14.4 to 14.8 and that is not correct for his vehicle.
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It was a qualified statement - if you read it properly .
Anyway - has the OP sorted it yet?
.14.4 to 14.8V @2000rpm. all in the CFAQ section
Anyway - has the OP sorted it yet?
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It was a qualified statement - if you read it properly
You have an 'ology ...
toms3
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The resistors haven't landed yet but I did make a start with some small resistors from maplins. I started with the exiter wire going to the fuel stop solenoid but when I turned the key off it kept running! so where the eiter wire connects must produce some power too? its now wired to the cig lighter which was an ignition live. I tested it with maplins resistors starting with smallest and went up in size just until the alternator kicks in (ill use this just until the 100 ohm resistors arrive). I plan to put an inline fuse on the wire too. testing it at the battery im getting 14v and I can hear the alternator working too. so its all working fine now although id like to get to the bottom of the problem and get it working through the dash and get oil pressure light working at the same time. is there a loom available that plugs into the plug socket at the bulkhead? just the under bonnet side as to be honest the wires look a bit old and are stiff from the engine heat.
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Autosparks or make it yourself. Easy to do if done properly.
toms3
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Thank you mad hat man
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yup the alternator creates 12v on that wire - that is why when you turn the ign on, volts flow from the 12v ign switch, through a lightbulb to the alternator which is at ground potential. that is why the bulb lights. As soon as the alternator is driven, then it also produces 12volts, so no voltage difference across the bulb and so it goes out.
toms3
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aaaa right cheers, iv been wondering how that worked.
Just out of interest, iv not done this iv used a resistor but - what would happen if you didn't use a resistor and just put 12v to it?
Potentially you could damage the alternator as the bulb/resistor limits the excitation current flow in to the alternator, also when it is running the 12v generated by the alternator excitation wire (that puts the light out) would then be fed straight back on to the switched 12v supply line and if excessive current is drawn from that supply it could damage the rectifier pack in the alternator that is used to generate the bulb 12v. There are normally nine diodes in the alternator, 6 are high current ones that convert the 3 phase 'main' power from AC to DC for battery charging and general running, the other 3 are low current ones for the warning lamp system and it is these three that could be damaged if there is no bulb/resistor to limit the current.
