alternator charges only for a few minutes
#1
04-27-2013, 04:38 PM
alternator charges only for a few minutes
My car charges for a few minutes anytime I start up the car, even if its all warmed up. The battery light on the dash is very dim, but is on. I've tried everything this forum has talked about. Changed the positive, and the problem persisted. Changed the negative wires grounded to the transmission and car body and problem persists. I checked fuse 82 on my multimeter and shows its fine. Maybe my car is getting too hot? The temperature guage is exactly in the middle. I really don't know what to do anymore.
#3
04-28-2013, 09:43 AM
Veteran Member
The battery light comes on at a low voltage level (I don't remember the exact low voltage point)..But I had the same problem and I ended up REPLACING ALL the battery wires from the battery to the fuse box, to the Starter motor and Alternator and all the Black Ground wires..
A JAG expert told me that this was a common problem with some of the X's and the wires develop a HIGH resistance and impedes current flow and lowers the voltage to the battery or from the battery..More than likely it is the Charging wire from the alternator..but rather than piece mill it and second guess, I changed out ALL the wires..Problem went away..and I had like 14+ volts at the battery while it was running at idle.
A JAG expert told me that this was a common problem with some of the X's and the wires develop a HIGH resistance and impedes current flow and lowers the voltage to the battery or from the battery..More than likely it is the Charging wire from the alternator..but rather than piece mill it and second guess, I changed out ALL the wires..Problem went away..and I had like 14+ volts at the battery while it was running at idle.
#4
04-28-2013, 04:21 PM
#6
04-28-2013, 08:24 PM
Veteran Member
Clean the Ground connection to the BODY real good at the drivers side just behind the headlight area.
Look at the BATTERY terminal voltage as the car is running at idle..When you first start it, it will be high for a few minutes of around 14+volts to bring the battery voltage back up to full charge from the losses from cranking, and then drops off to something around 13.5V..If this doesn't happen and remains low at around 12V or less, then you may have a bad alternator.
Look at the BATTERY terminal voltage as the car is running at idle..When you first start it, it will be high for a few minutes of around 14+volts to bring the battery voltage back up to full charge from the losses from cranking, and then drops off to something around 13.5V..If this doesn't happen and remains low at around 12V or less, then you may have a bad alternator.
Last edited by DPK; 04-29-2013 at 05:18 PM.
#7
04-29-2013, 03:01 PM
An alternator/rectifier/regulator unit will show a dim error light if a rectifier diode is weak or failed.
This experience comes from an '88 VW with a Bosch alternator.
An alternator with a defective diode will produce charging voltage at low current levels, but cannot maintain charging voltage at the high current levels the alternator is designed to deliver.
It is hard for me to believe that our Jaguars do the basic battery charging task differently.
This experience comes from an '88 VW with a Bosch alternator.
An alternator with a defective diode will produce charging voltage at low current levels, but cannot maintain charging voltage at the high current levels the alternator is designed to deliver.
It is hard for me to believe that our Jaguars do the basic battery charging task differently.
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#8
04-29-2013, 05:14 PM
Veteran Member
Get use to it bigdiver..Jaguar does a lot of things differently than other cars makers..
Here is a discription of how the charging system works in an X type..as I briefly explained earlier.
Here is a discription of how the charging system works in an X type..as I briefly explained earlier.
The engine control module (ECM) can switch the voltage between two voltages to optimize the charging of the battery.
The low voltage regulator setting is 13.6 volts and the high voltage regulator setting is 15.3 volts , measured with the generator at 25 degrees C (77 degrees F) and charging at a rate of 5 amps . These values decrease with a rise in temperature or current flow.
The ECM determines the voltage setting of the voltage regulator. The high voltage setting is always selected by the ECM once the vehicle has started. The ECM determines the period of time that the high voltage setting is selected for.
There are three different time periods selected by the ECM which is dependent upon the vehicle conditions when the vehicle is started:
1. The longest time period is selected if the ECM determines that the vehicle has been 'soaking' for sufficient time to allow the engine coolant temperature (ECT) and the intake air temperature (IAT) to fall within 3 degrees C (37 degrees F) of each other.
2. The intermediate time period is selected when the ECT and the IAT is below 5 degrees C (41 degrees F) .
3. The shortest time period is the default time and is used to provide a short period of boost charge.
At the end of these time periods the voltage is always set to the low voltage setting to prevent the battery from being overcharged.
The time periods are variable depending upon the temperature and the battery voltage. The target voltage of the battery varies between 14 volts and 15 volts depending upon the ambient temperature and the vehicle operating conditions. Once this target voltage has been achieved, providing the vehicle has been operating for at least the shortest time period, the ECM will reduce the voltage regulator to the minimum setting of 13.6 volts .
The low voltage regulator setting is 13.6 volts and the high voltage regulator setting is 15.3 volts , measured with the generator at 25 degrees C (77 degrees F) and charging at a rate of 5 amps . These values decrease with a rise in temperature or current flow.
The ECM determines the voltage setting of the voltage regulator. The high voltage setting is always selected by the ECM once the vehicle has started. The ECM determines the period of time that the high voltage setting is selected for.
There are three different time periods selected by the ECM which is dependent upon the vehicle conditions when the vehicle is started:
1. The longest time period is selected if the ECM determines that the vehicle has been 'soaking' for sufficient time to allow the engine coolant temperature (ECT) and the intake air temperature (IAT) to fall within 3 degrees C (37 degrees F) of each other.
2. The intermediate time period is selected when the ECT and the IAT is below 5 degrees C (41 degrees F) .
3. The shortest time period is the default time and is used to provide a short period of boost charge.
At the end of these time periods the voltage is always set to the low voltage setting to prevent the battery from being overcharged.
The time periods are variable depending upon the temperature and the battery voltage. The target voltage of the battery varies between 14 volts and 15 volts depending upon the ambient temperature and the vehicle operating conditions. Once this target voltage has been achieved, providing the vehicle has been operating for at least the shortest time period, the ECM will reduce the voltage regulator to the minimum setting of 13.6 volts .
#9
04-30-2013, 02:17 PM
#10
04-30-2013, 02:42 PM
Veteran Member
Diodes do not become weak..They fail usually by first shorting then they open...In other words, they are either GOOD or BAD, I've never seen a a weak diode ...Whatever it is you are try to say about the Dim light, but it could mean that One or more of the Alternator's Diodes have opened and it is outputting Half-Wave rectification..Conclusion could be as I said..BAD Alternator.
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