Alternator outputs?
09-10-2005, 03:09 PM
#16
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Thread Starter
Originally Posted by docmirror
I recommend the 7X series for auto appliction. These are pricey items, so you may want to shop around for something similar. I have Fluke equipment and would never use anything else. Anyway, as you may have read in the sticky posts at the top of the 928 forum, our cars suffer from many and varied electrical issues. Your's is not all that different from some of the others.
Set the meter aside and find a Pep Boys Hydrometer to check you're battery electolyte. It's simple and fast. If the red ball floats and the green doesn't you're battery is weak. Put the charger on it for a while, and then recheck. Start with a fully charged battery! 928s are tough on batteries.
Once the battery is up to snuff, turn off all your interior courtesy lights and lets use the meter.
Check the voltage at the + battery post and the bolt for the ground lug behind the tool tray. It should be around 12V. Leave the meter in place for the next tests.
Turn on the key, but do not start all the engine. Watch the meter, it will show a gradual discharge, but should not drop more than half volt in half a minute. Ignore the dash voltmeter.
Now start the engine, the voltmeter will drop a lot while cranking, but should begin to recover voltage once the engine is on an the alternator light is off. The ALT light is off, right?
At this point, if the voltmeter is showing a rise and gets to about 13.5V or so, your charging system is working in principal. The job of the alternator is to supply current to the car systems and recharge the battery to maintain a voltage sufficient to restart the car. Let the car run for a few minutes, or drive to the store or something. Don't shut it off.
Now the car is warmed up and running. Recheck the voltage at the battery terminals. Remember that number. Move around to the hood, and locate the jump start terminal on the pass fender. Check the voltage at the jump start point, and ground on the engine. Is the reading very close to the one from the battery? Within .2 Volts? If so, the charge line from the jump point back to the battery is good.
So, at this point, what does the voltmeter on the dash say? If the Fluke meter says things are alright, and the dash meter says 11-12V, I think you know where the problem is. Taking the dash out and testing the lines to the voltmeter is a fairly big job. Now you can check the output of the alternator.
Use the clamp meter around the cable to the + battery terminal. Try to keep it away from the battery case, and hold it perpendicular to the cable direction so you get a good reading. This is the recharge current. If the battery is in good shape, this should be fairly low after a modest drive. If it shows more than about 7-10A, the battery might be just worn out.
Now, take the Fluke meter and clamp around to the front. Locate the big charge line, coming from the cable harness that passes in front of the engine, and attaches to the jump lug. Clamp around the cable from that harness, before it reaches the jump lug. This is the current output of the alternator. At idle, with no acc on, it should probably read about 15A. Now rev the engine so it's stays at about 2700-3000RPM. Watch the meter, and start turning on acc. Start with the lights, then the wipers, then the AC, then the window motors up and down.
At this point the current should read about 45-55 Amps, maybe more. Leave all this on, disconnect the clamp ammeter from the Fluke, and check the voltage at the jump lug(2700-300RPM). It should still read around 13 volts. If it is much lower voltage than the resting voltage, the alternator may be weak. Leave all the stuff on, and go around to the batt. Connect the voltmeter to the batt + terminal and the ground bolt behind the tool tray. Again, around 13V, and close to the reading on the front of the pass jump lug.
I think we've gone far enough for now. Report back with your numbers and we'll take it up again depending on what you find. We may be looking at an uncalibrated dash voltmeter, but it's early to speculate too much. Remeber, during your tests, you are looking for trends, not absolute numbers. If the voltage at the jump lug is much different than the battery, that charge line to the back is a problem. If the current at the jump point really is over 100 amps with all the acc on, then something is wrong, and you will have to turn off curcuits one at a time to figure out where all the current is going.
Doc
Set the meter aside and find a Pep Boys Hydrometer to check you're battery electolyte. It's simple and fast. If the red ball floats and the green doesn't you're battery is weak. Put the charger on it for a while, and then recheck. Start with a fully charged battery! 928s are tough on batteries.
Once the battery is up to snuff, turn off all your interior courtesy lights and lets use the meter.
Check the voltage at the + battery post and the bolt for the ground lug behind the tool tray. It should be around 12V. Leave the meter in place for the next tests.
Turn on the key, but do not start all the engine. Watch the meter, it will show a gradual discharge, but should not drop more than half volt in half a minute. Ignore the dash voltmeter.
Now start the engine, the voltmeter will drop a lot while cranking, but should begin to recover voltage once the engine is on an the alternator light is off. The ALT light is off, right?
At this point, if the voltmeter is showing a rise and gets to about 13.5V or so, your charging system is working in principal. The job of the alternator is to supply current to the car systems and recharge the battery to maintain a voltage sufficient to restart the car. Let the car run for a few minutes, or drive to the store or something. Don't shut it off.
Now the car is warmed up and running. Recheck the voltage at the battery terminals. Remember that number. Move around to the hood, and locate the jump start terminal on the pass fender. Check the voltage at the jump start point, and ground on the engine. Is the reading very close to the one from the battery? Within .2 Volts? If so, the charge line from the jump point back to the battery is good.
So, at this point, what does the voltmeter on the dash say? If the Fluke meter says things are alright, and the dash meter says 11-12V, I think you know where the problem is. Taking the dash out and testing the lines to the voltmeter is a fairly big job. Now you can check the output of the alternator.
Use the clamp meter around the cable to the + battery terminal. Try to keep it away from the battery case, and hold it perpendicular to the cable direction so you get a good reading. This is the recharge current. If the battery is in good shape, this should be fairly low after a modest drive. If it shows more than about 7-10A, the battery might be just worn out.
Now, take the Fluke meter and clamp around to the front. Locate the big charge line, coming from the cable harness that passes in front of the engine, and attaches to the jump lug. Clamp around the cable from that harness, before it reaches the jump lug. This is the current output of the alternator. At idle, with no acc on, it should probably read about 15A. Now rev the engine so it's stays at about 2700-3000RPM. Watch the meter, and start turning on acc. Start with the lights, then the wipers, then the AC, then the window motors up and down.
At this point the current should read about 45-55 Amps, maybe more. Leave all this on, disconnect the clamp ammeter from the Fluke, and check the voltage at the jump lug(2700-300RPM). It should still read around 13 volts. If it is much lower voltage than the resting voltage, the alternator may be weak. Leave all the stuff on, and go around to the batt. Connect the voltmeter to the batt + terminal and the ground bolt behind the tool tray. Again, around 13V, and close to the reading on the front of the pass jump lug.
I think we've gone far enough for now. Report back with your numbers and we'll take it up again depending on what you find. We may be looking at an uncalibrated dash voltmeter, but it's early to speculate too much. Remeber, during your tests, you are looking for trends, not absolute numbers. If the voltage at the jump lug is much different than the battery, that charge line to the back is a problem. If the current at the jump point really is over 100 amps with all the acc on, then something is wrong, and you will have to turn off curcuits one at a time to figure out where all the current is going.
Doc
Okay, I can't yet test the amperage at the indicated locations, but..
The pre start voltage at the battery is 12.4 volts, if the key is turned on, it drops verrrrry slowly to about 12.3 volts.
When the engine is started, it drops momentarily, starte , to about 11 volts and then immediately goes up to 13.6 - 13.7 volts after it starts, all measured at the battery.
I checked the voltage at the jump lug and it was 13.7 volts, I returned immediately to the battery and it was 13.7 volts.
The dash still reads about 12 volts..
I'll get the amperage draws as soon as I can and get back.
Thanks
09-10-2005, 03:24 PM
#17
Rennlist Member
Thread Starter
Originally Posted by sublimate
Before you pull your pod you should check your voltages at the fuse/relay panel. My dash voltmeter was reading way low (off scale) so I checked with my multimeter and found good voltage at the battery and jump start terminal. But at the fuses I'm getting only 11.3 volts for the constant power circuit (30) and only 10.5 volts 
for the switched power circuit (15) - which is what the dash voltmeter is reading.
Time for more troubleshooting.
for the switched power circuit (15) - which is what the dash voltmeter is reading.Time for more troubleshooting.
Is it necessary to pull the fuse/relay panel?
Rod
09-10-2005, 09:55 PM
#18
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Probably don't have a good ground. Find a ground, probably aroudn the bolts that hold the LH/EZK to the chassis. It's on the far right side of the pass footwell, covered by a carpeted panel. Those bolts that hold the framework in should provide a good ground. With a file, shapen the point of the red terminal probe from your meter so that it's like a dull needle. You can then get down in the fuse lug without moving the fuses.
If your dash meter is showing 12V, and the DMM voltage is 13.6, it's typical of the voltmeters on these cars. My 90GT will only show 13 volts when it's recharging the battery. Once the battery voltage is nominal, the goes down to just above 12V line, and drops slightly with AC, fan, and lights on. Your's is reading pretty well considering. AFter all it's an uncalibrated meter, more for trend reference than anything else. Get used to where it runs with the car operating well, and then you will be able to sense a fault if the voltage goes below 11V, or way up.
I like that the voltage at the jump lug,a dn the batt is at 13.6. That just happens to be the correct voltage for the regulator on the alternator. This is a good indication that both the alt and the regulator are doing the job correctly. Since you don't have the ammeter yet, set the voltmeter on the jump lug, and ground on the engine, then rev to 12700RPM, and start turning on accesories. Watch the voltage as the accesories come on. The voltage will sag just a little, but should remain above 13.2 or so. If it does, then the load of the acc is being borne by the alternator and the regulator is doing it's job of keeping the voltage steady in the face of increasing load.
Now, leave the acc on, and let the car go down to idle. The voltage will sag quite a bit, because the alternator will not put out sufficient current at low RPM. Now rev it back up again, and the voltage should rebound back up around 13.2-13.6V.
After this we can start looking at the gauge delivery voltage from the fuse panel.
Doc
If your dash meter is showing 12V, and the DMM voltage is 13.6, it's typical of the voltmeters on these cars. My 90GT will only show 13 volts when it's recharging the battery. Once the battery voltage is nominal, the goes down to just above 12V line, and drops slightly with AC, fan, and lights on. Your's is reading pretty well considering. AFter all it's an uncalibrated meter, more for trend reference than anything else. Get used to where it runs with the car operating well, and then you will be able to sense a fault if the voltage goes below 11V, or way up.
I like that the voltage at the jump lug,a dn the batt is at 13.6. That just happens to be the correct voltage for the regulator on the alternator. This is a good indication that both the alt and the regulator are doing the job correctly. Since you don't have the ammeter yet, set the voltmeter on the jump lug, and ground on the engine, then rev to 12700RPM, and start turning on accesories. Watch the voltage as the accesories come on. The voltage will sag just a little, but should remain above 13.2 or so. If it does, then the load of the acc is being borne by the alternator and the regulator is doing it's job of keeping the voltage steady in the face of increasing load.
Now, leave the acc on, and let the car go down to idle. The voltage will sag quite a bit, because the alternator will not put out sufficient current at low RPM. Now rev it back up again, and the voltage should rebound back up around 13.2-13.6V.
After this we can start looking at the gauge delivery voltage from the fuse panel.
Doc
09-10-2005, 09:58 PM
#19
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Misprint, please don't rev your engine to twelve thousand, seven hundred RPM. It should read 2700. 
Originally Posted by docmirror
then rev to 12700RPM, and ...
Doc
Doc
09-10-2005, 10:17 PM
#20
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Thread Starter
Okay, I couldn't get the 12,700, it started misfiring at about 11,000 so I had to have my wife let off a bit. She was starting to cry. ;-)
At 2700 rpm, it reads 13.8 or 13.7 volts consistently. When everything is turned on, at 2700 rpm, it reads about 13.4 volts. Dropping down to an idle, it reads 12.4-12.5 volts steadly.
Looks from my uneducated eye that the alternator and regulator are working fine.
Rod
I haven't tried pulling the carpet back out to get to the fuse panel to recheck that. I can attack that in the morning.
Thanks for your help, it's reassuring.
I just installed my performance chips this morning and a permanent connection for battery maintenance during it's passive time this winter.
The chips, from my wishful thinking mind, seem to make it more responsive and it seems to be idling more smoothly than before, but that may be a result of having the battery disconnected for a while.
At 2700 rpm, it reads 13.8 or 13.7 volts consistently. When everything is turned on, at 2700 rpm, it reads about 13.4 volts. Dropping down to an idle, it reads 12.4-12.5 volts steadly.
Looks from my uneducated eye that the alternator and regulator are working fine.
Rod
I haven't tried pulling the carpet back out to get to the fuse panel to recheck that. I can attack that in the morning.
Thanks for your help, it's reassuring.
I just installed my performance chips this morning and a permanent connection for battery maintenance during it's passive time this winter.
The chips, from my wishful thinking mind, seem to make it more responsive and it seems to be idling more smoothly than before, but that may be a result of having the battery disconnected for a while.
Last edited by Rod Underwood; 09-11-2005 at 05:22 PM.
09-11-2005, 04:03 AM
#21
Drifting
Originally Posted by Rod Underwood
The chips, from my wishful thinking mind, seem to make it more responsive and it seems to be idling more smoothly than before, but that may be a result of having the battery disconnected for a while.
09-11-2005, 11:30 AM
#22
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Thread Starter
Originally Posted by sublimate
Before you pull your pod you should check your voltages at the fuse/relay panel. My dash voltmeter was reading way low (off scale) so I checked with my multimeter and found good voltage at the battery and jump start terminal. But at the fuses I'm getting only 11.3 volts for the constant power circuit (30) and only 10.5 volts for the switched power circuit (15) - which is what the dash voltmeter is reading.
Time for more troubleshooting.
for the switched power circuit (15) - which is what the dash voltmeter is reading.Time for more troubleshooting.
The wiring diagram indicates that this is relay XIII and since it's in place, I assume it may be bad?
Last edited by Rod Underwood; 09-11-2005 at 05:23 PM.
09-11-2005, 06:31 PM
#23
Rennlist Member
Thread Starter
Originally Posted by docmirror
I recommend the 7X series for auto appliction. These are pricey items, so you may want to shop around for something similar. I have Fluke equipment and would never use anything else. Anyway, as you may have read in the sticky posts at the top of the 928 forum, our cars suffer from many and varied electrical issues. Your's is not all that different from some of the others.
Set the meter aside and find a Pep Boys Hydrometer to check you're battery electolyte. It's simple and fast. If the red ball floats and the green doesn't you're battery is weak. Put the charger on it for a while, and then recheck. Start with a fully charged battery! 928s are tough on batteries.
Once the battery is up to snuff, turn off all your interior courtesy lights and lets use the meter.
Check the voltage at the + battery post and the bolt for the ground lug behind the tool tray. It should be around 12V. Leave the meter in place for the next tests.
Turn on the key, but do not start all the engine. Watch the meter, it will show a gradual discharge, but should not drop more than half volt in half a minute. Ignore the dash voltmeter.
Now start the engine, the voltmeter will drop a lot while cranking, but should begin to recover voltage once the engine is on an the alternator light is off. The ALT light is off, right?
At this point, if the voltmeter is showing a rise and gets to about 13.5V or so, your charging system is working in principal. The job of the alternator is to supply current to the car systems and recharge the battery to maintain a voltage sufficient to restart the car. Let the car run for a few minutes, or drive to the store or something. Don't shut it off.
Now the car is warmed up and running. Recheck the voltage at the battery terminals. Remember that number. Move around to the hood, and locate the jump start terminal on the pass fender. Check the voltage at the jump start point, and ground on the engine. Is the reading very close to the one from the battery? Within .2 Volts? If so, the charge line from the jump point back to the battery is good.
So, at this point, what does the voltmeter on the dash say? If the Fluke meter says things are alright, and the dash meter says 11-12V, I think you know where the problem is. Taking the dash out and testing the lines to the voltmeter is a fairly big job. Now you can check the output of the alternator.
Use the clamp meter around the cable to the + battery terminal. Try to keep it away from the battery case, and hold it perpendicular to the cable direction so you get a good reading. This is the recharge current. If the battery is in good shape, this should be fairly low after a modest drive. If it shows more than about 7-10A, the battery might be just worn out.
Now, take the Fluke meter and clamp around to the front. Locate the big charge line, coming from the cable harness that passes in front of the engine, and attaches to the jump lug. Clamp around the cable from that harness, before it reaches the jump lug. This is the current output of the alternator. At idle, with no acc on, it should probably read about 15A. Now rev the engine so it's stays at about 2700-3000RPM. Watch the meter, and start turning on acc. Start with the lights, then the wipers, then the AC, then the window motors up and down.
At this point the current should read about 45-55 Amps, maybe more. Leave all this on, disconnect the clamp ammeter from the Fluke, and check the voltage at the jump lug(2700-300RPM). It should still read around 13 volts. If it is much lower voltage than the resting voltage, the alternator may be weak. Leave all the stuff on, and go around to the batt. Connect the voltmeter to the batt + terminal and the ground bolt behind the tool tray. Again, around 13V, and close to the reading on the front of the pass jump lug.
I think we've gone far enough for now. Report back with your numbers and we'll take it up again depending on what you find. We may be looking at an uncalibrated dash voltmeter, but it's early to speculate too much. Remeber, during your tests, you are looking for trends, not absolute numbers. If the voltage at the jump lug is much different than the battery, that charge line to the back is a problem. If the current at the jump point really is over 100 amps with all the acc on, then something is wrong, and you will have to turn off curcuits one at a time to figure out where all the current is going.
Doc
Set the meter aside and find a Pep Boys Hydrometer to check you're battery electolyte. It's simple and fast. If the red ball floats and the green doesn't you're battery is weak. Put the charger on it for a while, and then recheck. Start with a fully charged battery! 928s are tough on batteries.
Once the battery is up to snuff, turn off all your interior courtesy lights and lets use the meter.
Check the voltage at the + battery post and the bolt for the ground lug behind the tool tray. It should be around 12V. Leave the meter in place for the next tests.
Turn on the key, but do not start all the engine. Watch the meter, it will show a gradual discharge, but should not drop more than half volt in half a minute. Ignore the dash voltmeter.
Now start the engine, the voltmeter will drop a lot while cranking, but should begin to recover voltage once the engine is on an the alternator light is off. The ALT light is off, right?
At this point, if the voltmeter is showing a rise and gets to about 13.5V or so, your charging system is working in principal. The job of the alternator is to supply current to the car systems and recharge the battery to maintain a voltage sufficient to restart the car. Let the car run for a few minutes, or drive to the store or something. Don't shut it off.
Now the car is warmed up and running. Recheck the voltage at the battery terminals. Remember that number. Move around to the hood, and locate the jump start terminal on the pass fender. Check the voltage at the jump start point, and ground on the engine. Is the reading very close to the one from the battery? Within .2 Volts? If so, the charge line from the jump point back to the battery is good.
So, at this point, what does the voltmeter on the dash say? If the Fluke meter says things are alright, and the dash meter says 11-12V, I think you know where the problem is. Taking the dash out and testing the lines to the voltmeter is a fairly big job. Now you can check the output of the alternator.
Use the clamp meter around the cable to the + battery terminal. Try to keep it away from the battery case, and hold it perpendicular to the cable direction so you get a good reading. This is the recharge current. If the battery is in good shape, this should be fairly low after a modest drive. If it shows more than about 7-10A, the battery might be just worn out.
Now, take the Fluke meter and clamp around to the front. Locate the big charge line, coming from the cable harness that passes in front of the engine, and attaches to the jump lug. Clamp around the cable from that harness, before it reaches the jump lug. This is the current output of the alternator. At idle, with no acc on, it should probably read about 15A. Now rev the engine so it's stays at about 2700-3000RPM. Watch the meter, and start turning on acc. Start with the lights, then the wipers, then the AC, then the window motors up and down.
At this point the current should read about 45-55 Amps, maybe more. Leave all this on, disconnect the clamp ammeter from the Fluke, and check the voltage at the jump lug(2700-300RPM). It should still read around 13 volts. If it is much lower voltage than the resting voltage, the alternator may be weak. Leave all the stuff on, and go around to the batt. Connect the voltmeter to the batt + terminal and the ground bolt behind the tool tray. Again, around 13V, and close to the reading on the front of the pass jump lug.
I think we've gone far enough for now. Report back with your numbers and we'll take it up again depending on what you find. We may be looking at an uncalibrated dash voltmeter, but it's early to speculate too much. Remeber, during your tests, you are looking for trends, not absolute numbers. If the voltage at the jump lug is much different than the battery, that charge line to the back is a problem. If the current at the jump point really is over 100 amps with all the acc on, then something is wrong, and you will have to turn off curcuits one at a time to figure out where all the current is going.
Doc
Okay,
At idle, with one door open, it draws about 21.9 amps at the battery and 8.8 amps at the jump lug. At 3000 RPM, it draws 9.4 at the jump lug, progressively, as I turn on the lights, it draws 34.7 amps, +AC on- 37.5 amps, +interior fan - 52 amps, + windows going up and down - 61 amps. With everything still on, it shows 47 amps at idle. All of these readings are at the jump lug.
I revisited the tests at the battery terminal. Just for additional information, it draws 7.5 amps at key turn, and 66 amps on start crank. IT settles down to 33.5 amps after starting, and progressively draws 36 amps with lights, +AC - 36.5 amps, +AC Blower - 38 amps, + windows - 41 amps all at 3000 rpm. at idle it drops to 17.5 amps.
Some big discrepencies between jump lug and battery readings.
Based on your numbers, these seem high, especially at no load.
The voltages that I checked last night for these conditions seem in range.
Rod
Rod
Last edited by Rod Underwood; 09-11-2005 at 06:55 PM.
09-12-2005, 02:50 AM
#24
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Rod, I think everything reads pretty good. These are numbers I expect with the car just being started and not driven. The battery is a chemical current storage device. It will take a half hour driving to recover full charge after the car has been sitting for a while, then you start testing, then crank start it, then start testing amps.
If you put the car on your overnight charger, then start the car, take it for a drive, bring it back and check the current at the batt, it will be lower as long as you keep the RMP up around 3000. Here's the thing, you never know which way the current is flowing with a clamp on. When the car was started, all the current was flowing out of course. However, once the alt came online, all the current was then flowing back into the battery. When you sit at a red light, with the AC on, lights on brake lights on, radio, etc, your battery is supplying much of the current needed to run the car and the acc. As you drive off from the light, the alternator, aided by the voltage regulator will assume the load of the car, and also send current back to the battery to maintain it at the proper charge state.
Did you get the cheapo Hydrometer? No - you - di-unt! This will tell you the condition of the chemistry in your battery. It should be in EVERY 928 toolbox. 3 bucks, easy to read, small, what's not to like? Your dash meter is a POS. only use it as a trend indicator. Realize that when it says 12V, it really means 13.6V. If you look down some day and see it at 10.5-11V, then I would get concerned.
As for your fuse readings, the voltage at the fuses should be hear 13V too. If you have a lighting problem, we need your symptoms, if any.
Doc
If you put the car on your overnight charger, then start the car, take it for a drive, bring it back and check the current at the batt, it will be lower as long as you keep the RMP up around 3000. Here's the thing, you never know which way the current is flowing with a clamp on. When the car was started, all the current was flowing out of course. However, once the alt came online, all the current was then flowing back into the battery. When you sit at a red light, with the AC on, lights on brake lights on, radio, etc, your battery is supplying much of the current needed to run the car and the acc. As you drive off from the light, the alternator, aided by the voltage regulator will assume the load of the car, and also send current back to the battery to maintain it at the proper charge state.
Did you get the cheapo Hydrometer? No - you - di-unt! This will tell you the condition of the chemistry in your battery. It should be in EVERY 928 toolbox. 3 bucks, easy to read, small, what's not to like? Your dash meter is a POS. only use it as a trend indicator. Realize that when it says 12V, it really means 13.6V. If you look down some day and see it at 10.5-11V, then I would get concerned.
As for your fuse readings, the voltage at the fuses should be hear 13V too. If you have a lighting problem, we need your symptoms, if any.
Doc
09-12-2005, 05:11 AM
#25
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Thread Starter
Originally Posted by docmirror
Rod, I think everything reads pretty good. These are numbers I expect with the car just being started and not driven. The battery is a chemical current storage device. It will take a half hour driving to recover full charge after the car has been sitting for a while, then you start testing, then crank start it, then start testing amps.
If you put the car on your overnight charger, then start the car, take it for a drive, bring it back and check the current at the batt, it will be lower as long as you keep the RMP up around 3000. Here's the thing, you never know which way the current is flowing with a clamp on. When the car was started, all the current was flowing out of course. However, once the alt came online, all the current was then flowing back into the battery. When you sit at a red light, with the AC on, lights on brake lights on, radio, etc, your battery is supplying much of the current needed to run the car and the acc. As you drive off from the light, the alternator, aided by the voltage regulator will assume the load of the car, and also send current back to the battery to maintain it at the proper charge state.
Did you get the cheapo Hydrometer? No - you - di-unt! This will tell you the condition of the chemistry in your battery. It should be in EVERY 928 toolbox. 3 bucks, easy to read, small, what's not to like? Your dash meter is a POS. only use it as a trend indicator. Realize that when it says 12V, it really means 13.6V. If you look down some day and see it at 10.5-11V, then I would get concerned.
As for your fuse readings, the voltage at the fuses should be hear 13V too. If you have a lighting problem, we need your symptoms, if any.
Doc
If you put the car on your overnight charger, then start the car, take it for a drive, bring it back and check the current at the batt, it will be lower as long as you keep the RMP up around 3000. Here's the thing, you never know which way the current is flowing with a clamp on. When the car was started, all the current was flowing out of course. However, once the alt came online, all the current was then flowing back into the battery. When you sit at a red light, with the AC on, lights on brake lights on, radio, etc, your battery is supplying much of the current needed to run the car and the acc. As you drive off from the light, the alternator, aided by the voltage regulator will assume the load of the car, and also send current back to the battery to maintain it at the proper charge state.
Did you get the cheapo Hydrometer? No - you - di-unt! This will tell you the condition of the chemistry in your battery. It should be in EVERY 928 toolbox. 3 bucks, easy to read, small, what's not to like? Your dash meter is a POS. only use it as a trend indicator. Realize that when it says 12V, it really means 13.6V. If you look down some day and see it at 10.5-11V, then I would get concerned.
As for your fuse readings, the voltage at the fuses should be hear 13V too. If you have a lighting problem, we need your symptoms, if any.
Doc
Actually I do have a couple of hydrometers, but you're right, I didn't check the battery, it was new in may, according to the warranty punchouts. I will check it.
I'm relieved that the original test was wrong and it's not drawing 188 amps. I guess the Advance Auto employee didn't have access to your expertise, or maybe just wasn't using his equipment correctly.
When I get my new relays in, I'll go a more thorough check of all the fuse voltages and also start locating all of the grounds to clean. I'll check the manual, I understand there are several locations.
Do you have a recommended dielectric "tune-up" that you use? I have some Permatex/Loctite 22058, but not sure it's the correct material for this application. I assume it would be good for the grounds, but the more delicate connections around the fuses and relays probably need something more sophisticated.
Thanks for all your assistance.
Rod
I picked my car up in Dallas a couple of weeks ago, I wish I could have bought you a Margarita at Billy Bobs over there in Foat Wuth. ;-)
I owe you in any event.
09-12-2005, 01:41 PM
#26
Shameful Thread Killer
Rennlist Member
Rennlist Member
Well, pardner, there's your mistake. You were in that *****- uh, I mean city to the east. Why they named it after a TV show, I'll never understand. The hydrometer will show the state of charge of the battery right away. I'll bet dollars to donuts if you let the car sit for a few weeks, then check the battery it'll show quite discharged. 928s are tough on batteries.
I don't have a recommendation for contact cleaner. Usually they all have some form of MEK, or acetone in them. For the grounds, there is an excellent article that I can't find right now about all the ground points and proper cleaning. For these, mechanical cleaning is important. Then put it all back together and after that I would spray some dull paint over the connection to help keep out oxidation.
As Wally has mentioned in previous articles, when you work on the fuse area, take every fuse out, clean it, check it electrically, and reinstall it. When I did that my dash lights started working and my central lock too! A fuse can appear good in the envelope but still have a hairline split in it. I've seen them.
Good luck with the relays, they're a pain to get out. I use hotdog tongs, but I'm weird. Note that not all relays are NOT the same, don't put them back in *****-nilly, or the car won't run.
Doc
(From that cool cowtown to the west of the big stinkhole)
I don't have a recommendation for contact cleaner. Usually they all have some form of MEK, or acetone in them. For the grounds, there is an excellent article that I can't find right now about all the ground points and proper cleaning. For these, mechanical cleaning is important. Then put it all back together and after that I would spray some dull paint over the connection to help keep out oxidation.
As Wally has mentioned in previous articles, when you work on the fuse area, take every fuse out, clean it, check it electrically, and reinstall it. When I did that my dash lights started working and my central lock too! A fuse can appear good in the envelope but still have a hairline split in it. I've seen them.
Good luck with the relays, they're a pain to get out. I use hotdog tongs, but I'm weird. Note that not all relays are NOT the same, don't put them back in *****-nilly, or the car won't run.
Doc
(From that cool cowtown to the west of the big stinkhole)
09-12-2005, 02:43 PM
#27
Rennlist Member
Thread Starter
Originally Posted by docmirror
Well, pardner, there's your mistake. You were in that *****- uh, I mean city to the east. Why they named it after a TV show, I'll never understand. The hydrometer will show the state of charge of the battery right away. I'll bet dollars to donuts if you let the car sit for a few weeks, then check the battery it'll show quite discharged. 928s are tough on batteries.
I don't have a recommendation for contact cleaner. Usually they all have some form of MEK, or acetone in them. For the grounds, there is an excellent article that I can't find right now about all the ground points and proper cleaning. For these, mechanical cleaning is important. Then put it all back together and after that I would spray some dull paint over the connection to help keep out oxidation.
As Wally has mentioned in previous articles, when you work on the fuse area, take every fuse out, clean it, check it electrically, and reinstall it. When I did that my dash lights started working and my central lock too! A fuse can appear good in the envelope but still have a hairline split in it. I've seen them.
Good luck with the relays, they're a pain to get out. I use hotdog tongs, but I'm weird. Note that not all relays are NOT the same, don't put them back in *****-nilly, or the car won't run.
Doc
(From that cool cowtown to the west of the big stinkhole)
I don't have a recommendation for contact cleaner. Usually they all have some form of MEK, or acetone in them. For the grounds, there is an excellent article that I can't find right now about all the ground points and proper cleaning. For these, mechanical cleaning is important. Then put it all back together and after that I would spray some dull paint over the connection to help keep out oxidation.
As Wally has mentioned in previous articles, when you work on the fuse area, take every fuse out, clean it, check it electrically, and reinstall it. When I did that my dash lights started working and my central lock too! A fuse can appear good in the envelope but still have a hairline split in it. I've seen them.
Good luck with the relays, they're a pain to get out. I use hotdog tongs, but I'm weird. Note that not all relays are NOT the same, don't put them back in *****-nilly, or the car won't run.
Doc
(From that cool cowtown to the west of the big stinkhole)
Hey, you know you have to stop in the town where your car catches on fire!!! Not much choice.
My fuse panel actually has a tester built into it but I'm replacing all of the fuses just to make sure. I found some at Advance Auto that have a light built in that comes on when the fuse fails. It seems like a nice idea in a dark place..
Always wanting more "speciality" tools, I bought one of the relay removal tools on sale from 928 Specialists, but they've all come out easily by hand so far. I may have to break it out just so I can say I used it.
I'll look for the ground article.
Thanks
Rod
