first stranding, alternator failure
- Thread starter jvandyke
- Start date
Not the case
Because if that were true, your charge circuit would only see about 0.5 amps at best (even less!) of charge current.
The lamp only lights up on a "negative" current flow.
Also, FYI - you have to rev up the car to at least 2500 RPM to get the alternator "kick-started".
Enjoy!
Because if that were true, your charge circuit would only see about 0.5 amps at best (even less!) of charge current.
The lamp only lights up on a "negative" current flow.
Also, FYI - you have to rev up the car to at least 2500 RPM to get the alternator "kick-started".
Enjoy!
Yes...
If there is no charge warning bulb illumination with key "on", the alternator will not charge upon starting.
First thing I look at with these cars, and my Vanagon, and Dr. Wifey's 320i. All the same.
The light should illuminate when the key is turned to "on" and go out upon startup, sometimes you need to blip the throttle to get it to go out. Until it does there is no charging.
If there is no charge warning bulb illumination with key "on", the alternator will not charge upon starting.
First thing I look at with these cars, and my Vanagon, and Dr. Wifey's 320i. All the same.
The light should illuminate when the key is turned to "on" and go out upon startup, sometimes you need to blip the throttle to get it to go out. Until it does there is no charging.
jvandyke
True Classic
I don't quite get it either but I thought the idiot light gets current with key on, it lights, when engine running current comes at it from the alternator and the electrickity elves meet at the bulb and institute a stalemate whereby no one lights the bulb, if one elf army issues a retreat, the bulb lights and you're not charging anymore, unless the bulb is burned out; open circuit and all the elves escape together and start a commune in Idaho.
Black-Tooth
Tony Natoli
If I may jump into the frey...
or is it "frucus"...
This may be my FIRST disagreement with Greg and my FIRST agreement with Bob for 2012!
The red indicator light that tells you the alternator is charging or not charging... should be just that, an INDICATOR.
It should NOT be part of the circuit or necessary for the charging circuit to work.
This can be proven by Jeff with his trusty $2.99 Harbor Freight VOM by placing it across the battery terminals... insuring the alternator is charging, and then removing the indicator lamp and testing again.
I BELIEVE you will see that Bob and I are correct... and I'm afraid the original problem is/was something else.
or is it "frucus"...
This may be my FIRST disagreement with Greg and my FIRST agreement with Bob for 2012!
The red indicator light that tells you the alternator is charging or not charging... should be just that, an INDICATOR.
It should NOT be part of the circuit or necessary for the charging circuit to work.
This can be proven by Jeff with his trusty $2.99 Harbor Freight VOM by placing it across the battery terminals... insuring the alternator is charging, and then removing the indicator lamp and testing again.
I BELIEVE you will see that Bob and I are correct... and I'm afraid the original problem is/was something else.
Rupunzell
Bernice Loui
+1
The indicator light connection is to indicate the alternator is not producing power... nothing more. In the stock exxe, the alternator indicator lamp is in series with the D+ connection. This the alternator field connection which tells the alternator to produce power.
In some modern alternators, the D+ or field connection is a separate connection from the alternator not producing power connection. These are two distinctly different connections with two distinctly different functions.
The sense connection for sensing the point (node) where the correct voltage must be. As a viable option, this connection can be wired direct to the alternator main output stud.
The field connection tells the alternator to produce power. It is usually connected to the ignition switch.. running on position.
The main power connection (externally threaded stud) is connected directly to the battery positive.
With all these connections in place, run the engine and measure the voltage at the battery, the voltage reading should not be less than 13 Volts DC. If it is, there is a problem with the connections or a problem with the alternator.
There are "one wire" or single wire alternators on the market.. stay away from these as they have a different set of problems.
Bernice
The indicator light connection is to indicate the alternator is not producing power... nothing more. In the stock exxe, the alternator indicator lamp is in series with the D+ connection. This the alternator field connection which tells the alternator to produce power.
In some modern alternators, the D+ or field connection is a separate connection from the alternator not producing power connection. These are two distinctly different connections with two distinctly different functions.
The sense connection for sensing the point (node) where the correct voltage must be. As a viable option, this connection can be wired direct to the alternator main output stud.
The field connection tells the alternator to produce power. It is usually connected to the ignition switch.. running on position.
The main power connection (externally threaded stud) is connected directly to the battery positive.
With all these connections in place, run the engine and measure the voltage at the battery, the voltage reading should not be less than 13 Volts DC. If it is, there is a problem with the connections or a problem with the alternator.
There are "one wire" or single wire alternators on the market.. stay away from these as they have a different set of problems.
Bernice
Tony, Tony, Tony...
The Bosch system uses the "charge indicator" bulb in series with the charging "exciter" circuit. Look at the wiring diagrams for the late cars with "internal" regulator:
One side of the "charge indicator" is from the D+ post on the alternator (black/violet wire), the other goes to key-on power through the ignition switch. In this way it works as jvandyke explains, clever really. It illuminates when there is a differential between the power it sees at the battery (via ignition switch) and the power it sees from the charging system (via D+ terminal). This is why it glows sometimes, the amount of illumination is determined by the amount of the battery/alternator output differential. When/if the bulb is burnt out, there is no exciter circuit for the alternator.
The Bosch system uses the "charge indicator" bulb in series with the charging "exciter" circuit. Look at the wiring diagrams for the late cars with "internal" regulator:
One side of the "charge indicator" is from the D+ post on the alternator (black/violet wire), the other goes to key-on power through the ignition switch. In this way it works as jvandyke explains, clever really. It illuminates when there is a differential between the power it sees at the battery (via ignition switch) and the power it sees from the charging system (via D+ terminal). This is why it glows sometimes, the amount of illumination is determined by the amount of the battery/alternator output differential. When/if the bulb is burnt out, there is no exciter circuit for the alternator.
Dayton Tom
Tom Marcellino
Exciter wire
Searched online and the exciter wire (searched specific to GM alternator) is "usually wired through the charging indicator light".
Going through the Haynes wiring diagram, the black/purple wire from the alternator goes to large connector #22 on the gauge cluster. Comparing the manual to Bob's picture below, it is the negative side of the "alternator lamp". So if the lamp does not complete the circuit, then the exciter wire is dead. I know when I initially set mine up, I tested that wire to be sure it was hot with key on.
Searched online and the exciter wire (searched specific to GM alternator) is "usually wired through the charging indicator light".
Going through the Haynes wiring diagram, the black/purple wire from the alternator goes to large connector #22 on the gauge cluster. Comparing the manual to Bob's picture below, it is the negative side of the "alternator lamp". So if the lamp does not complete the circuit, then the exciter wire is dead. I know when I initially set mine up, I tested that wire to be sure it was hot with key on.
jvandyke
True Classic
no bulb=no charge, burnt bulb=no charge, GM CS130, YMMV
I didn't try a straight 12v to the exciter line on the alt since all the info said it must be resisted down, my hack job worked, and the restored bulb worked, that's all I know, the alternator would produce nothing without voltage on the exciter line.
I didn't try a straight 12v to the exciter line on the alt since all the info said it must be resisted down, my hack job worked, and the restored bulb worked, that's all I know, the alternator would produce nothing without voltage on the exciter line.
Black-Tooth
Tony Natoli
I stand corrected...
Clever as you all say... but unbelievable as well.
I can't believe that a cheap bulb could stop a car from operating in this manner. I wonder if this is the way it has always been (with GM alternators and the like) and I just never noticed... having been raised with Generators and relay operated Voltage Regulators.
Clever as you all say... but unbelievable as well.
I can't believe that a cheap bulb could stop a car from operating in this manner. I wonder if this is the way it has always been (with GM alternators and the like) and I just never noticed... having been raised with Generators and relay operated Voltage Regulators.
ng_randolph
Bjorn H
A number of cars of X1/9 vintage have a resistor in the cluster connected in parallel with the alternator bulb. Thus should the bulb burn out, the resistor will still provide current to the exciter. See the wiring diagrams for an '87 VW GTi 16V (found at www.gti16v.com). Note the resistor immediately to the right of the "ALT WARN LITE":
jvandyke
True Classic
Very good question. I'd imagine no go with LED. Might be a good idea to hook up another way to excite the alt (GM) or at least have an alternate method at hand (a 40 year old emergency light, with crumbling insulation I just happen to have stashed in the glove box worked for me but a simple 10w or so bulb on a wire could be handy if the charge light burns out your done.
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lookforjoe
True Classic
That explains why mine (with one of Bob's modified clusters) does not charge until I rev the motor around 2K - not something I'd want to do stone cold in low ambient temps, but I don't drive the car in the winter as a rule.
I believe most LED's are polarized, though.
EDIT: I think I'll add a 35ohm resistor to the circuit board, like the VW setup...
I've never had a charging issue
by using LED's. YES, you have to rev up the engine to above 2000 rpm to kick-start the alternator, but the LED itself will not cause the charge circuit to work or fail.
Just another thought... If you think the lamp makes an over-all difference, remember that the lamp is pressed into a holder that is less than ideal (connection-wise) then it makes contact with a bare copper "twist" connection on the back of the cluster. From there, one side goes through a diode to the "hot" line side of the car (yet through another connector) while the other side goes to the + Battery. If our charging systems truly relied on this "connection" to feed back the alternator field winding, we'd all be walking...
The LED indicates FAR IN ADVANCE of an incandescent bulb due to it's low current requirement, and that's why it stays on longer. It does not feed your charge system in the X.
With an incandescent lamp, you'd see a weak glow, and it goes out (literally) while an LED in it's place would still shine bright.
Prove it to yourself by replacing the bulb, start your car at low RPM and drop a meter across the battery. You will not see a "start charging" difference based on RPM regardless of the lamp.
:sun:
by using LED's. YES, you have to rev up the engine to above 2000 rpm to kick-start the alternator, but the LED itself will not cause the charge circuit to work or fail.
Just another thought... If you think the lamp makes an over-all difference, remember that the lamp is pressed into a holder that is less than ideal (connection-wise) then it makes contact with a bare copper "twist" connection on the back of the cluster. From there, one side goes through a diode to the "hot" line side of the car (yet through another connector) while the other side goes to the + Battery. If our charging systems truly relied on this "connection" to feed back the alternator field winding, we'd all be walking...
The LED indicates FAR IN ADVANCE of an incandescent bulb due to it's low current requirement, and that's why it stays on longer. It does not feed your charge system in the X.
With an incandescent lamp, you'd see a weak glow, and it goes out (literally) while an LED in it's place would still shine bright.
Prove it to yourself by replacing the bulb, start your car at low RPM and drop a meter across the battery. You will not see a "start charging" difference based on RPM regardless of the lamp.
:sun:
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ng_randolph
Bjorn H
bbrown said:
The alternator relies on current through the alternator light only to get started. Once it is generating voltage (as indicated by the light turning off) you could remove the bulb (or break the circuit in some other way) and the alternator would keep charging. The diagram below (lifted from bmwmotorcycletech.info) shows why:
Current to the field winding (through the voltage regulator) normally comes from the diode trio labeled "small diodes" towards the top of the diagram. When you first start spinning the alternator, there will be no field current and thus the alternator will not generate any voltage. And when the alternator is not generating voltage it can not drive current through the field winding. The voltage regulator will not see battery voltage since it is isolated from the battery by the now reverse biased diodes (right pointing in the diagram)
This is where current through the alternator light boot-straps the process. The current through the lamp energizes the field winding and the alternator starts delivering power. Once going, current for the field winding comes from the top diode trio.
The photo you show
certainly makes it look this way. But my stock X1/9 isn't like that.
My (stock) alternator has only 1 wire. This wire goes directly to the battery to charge it. The regulator is built-into the alternator.
Your alternator should work fine and charge your battery without plugging in a gauge cluster. Mine does, but I still have to rev the engine to get the alternator to start producing current.
Try it, you might be surprised.
certainly makes it look this way. But my stock X1/9 isn't like that.
My (stock) alternator has only 1 wire. This wire goes directly to the battery to charge it. The regulator is built-into the alternator.
Your alternator should work fine and charge your battery without plugging in a gauge cluster. Mine does, but I still have to rev the engine to get the alternator to start producing current.
Try it, you might be surprised.
jvandyke
True Classic
I did read somewhere that residual current in the windings can be enough to get the alternator charging if it hasn't sat too long, something like that. I don't really know, I'd experiment but I'd hate to jinx my now charging and 13.5ish running volt alternator, 105amp for $25, though I'm tempted to run straight 12v to it through the exciter line (idiot light), then try resisted voltage again, just to experiment.