Alternator heat soak...... how can i tell?
08-11-2011, 07:18 PM
#16
Thread Starter
so here is what i have so far.
voltage check at jump post and ground near by. car off.. 12.8
idle 12.8 ish
1500 13.32
idle radio on, ac full 12.74
1500 12.88
voltage check at jump post and ground near by. car off.. 12.8
idle 12.8 ish
1500 13.32
idle radio on, ac full 12.74
1500 12.88
08-11-2011, 07:30 PM
#17
Rennlist Member
Just a thought - So how about disconnecting the battery, putting it on a charger ( 12v/10A) for about 12 hours, and redoing the tests - if you don't go off base much it isn't getting enough of a run time to bring the battery up to optimum - maybe.
08-11-2011, 07:35 PM
#18
Thread Starter
i have an autometer battery tender i hook up when its parked. so its should be ok. im thinking of taking the batt in and the alternator anyway to get tested. battery first, its the easy one to get too.
08-11-2011, 07:37 PM
#19
Electron Wrangler
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Assume these are fully warmed up hot cases??
If this is hot idle its not too bad - but I'd say it sounds weak with 12.88v @ 1.5K - it should be well over 13v - do a few hunderd more rpms make any difference...?
What about at 2K with everything on... (and hot)
Since its an 'alternate' alternator - there is big question on the pulley ratios - if more rpms solves the problem better then maybe you need a bigger crank pulley or a smaller alt pully (or both). Is the belt really tight enough - it needs to be very tight...
Alan
If this is hot idle its not too bad - but I'd say it sounds weak with 12.88v @ 1.5K - it should be well over 13v - do a few hunderd more rpms make any difference...?
What about at 2K with everything on... (and hot)
Since its an 'alternate' alternator - there is big question on the pulley ratios - if more rpms solves the problem better then maybe you need a bigger crank pulley or a smaller alt pully (or both). Is the belt really tight enough - it needs to be very tight...
Alan
08-11-2011, 08:19 PM
#20
Thread Starter
belt check out tight. negative, the tests were done cold. im about to go drive her to warm her up then run tests again before i yank the alt out tonight. stand by for updates.
08-11-2011, 11:23 PM
#22
Chronic Tool Dropper
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Or a battery that's soaking up everything the alternator can dish out and more.
Battery discvonnected from car and charger overnight should give you about 12.4. Cranking should not drop below 10.5. Charging should be 13.8 cold, can drop to 13.2 or so hot. Worse than that is cause for concern.
The -only- reason to have higher voltage is to make sure there's enough to push charging current to the battery enough to recover from starting the car in the time that it's driven. Short trips and lots of idling mean that there's a need to take max advantage of the charging when it's available, so higher voltage may be needed.
I rumble around at low RPM's for the most part, and it takes its toll on the battery I think.
Battery discvonnected from car and charger overnight should give you about 12.4. Cranking should not drop below 10.5. Charging should be 13.8 cold, can drop to 13.2 or so hot. Worse than that is cause for concern.
The -only- reason to have higher voltage is to make sure there's enough to push charging current to the battery enough to recover from starting the car in the time that it's driven. Short trips and lots of idling mean that there's a need to take max advantage of the charging when it's available, so higher voltage may be needed.
I rumble around at low RPM's for the most part, and it takes its toll on the battery I think.
08-12-2011, 12:26 AM
#23
Thread Starter
i think thats what im going to do first. replace the battery. i took a look at it again, and its an el cheapo. tomorrow i will swap that baby out, take some readings, then go from there.
08-12-2011, 03:43 PM
#25
Thread Starter
iv decided to drive it more and see what happens. batt checks out ok, and voltage seems low, but its over 12 volts, so thats good atleast. i plan to see what i can come up with for a heat shield for the alt. im also thinking of building some kind of cold air shroud like the stock on.
08-12-2011, 04:34 PM
#26
Team Owner
This is what you need to see
If you disconnect the battery from the circuit with the engine running again you will be asked to turn in your 928 keys.
With a good volt meter you can check the engine running voltage output at the hot post and the battery,
this will let you know how good your connections are. The numbers should be very close
Keeping the engine running at 1500 RPM while testing will give accurate numbers.
This is most likely your issue
Disconnecting the battery from the charging system with the engine running will usually fry one or more of the 6 diodes in the alternator,
and or damage the voltage regulator
then this will require replacement of the alternator,
also the voltage spike can damage the ignition computer and may make the car shut off as the extra voltage will disrupt the ignition computer.
It may also damage the AC relay in HVAC head
What voltages your looking for are with the accessories turned on the charging system should be at 13.2 or more.
If with the acc. turned off , and 1500 RPM and you dont get over 13.5 then you have a blown diode in the alt. or the brushes in the regulator are worn
If with the voltage running over 14.6 then you have a failed voltage regulator
If you disconnect the battery from the circuit with the engine running again you will be asked to turn in your 928 keys.
With a good volt meter you can check the engine running voltage output at the hot post and the battery,
this will let you know how good your connections are. The numbers should be very close
Keeping the engine running at 1500 RPM while testing will give accurate numbers.
This is most likely your issue
Disconnecting the battery from the charging system with the engine running will usually fry one or more of the 6 diodes in the alternator,
and or damage the voltage regulator
then this will require replacement of the alternator,
also the voltage spike can damage the ignition computer and may make the car shut off as the extra voltage will disrupt the ignition computer.
It may also damage the AC relay in HVAC head
What voltages your looking for are with the accessories turned on the charging system should be at 13.2 or more.
If with the acc. turned off , and 1500 RPM and you dont get over 13.5 then you have a blown diode in the alt. or the brushes in the regulator are worn
If with the voltage running over 14.6 then you have a failed voltage regulator
08-12-2011, 07:12 PM
#30
Team Owner
can you post pictures of the alternator and its connections and its pulley
something doesnt sound right.
If the alternator wont put out more than 13.5 volts,
the battery will go dead as there isnt enough over 12v to charge the battery.
What were the test results of the alternator how much voltage was it producing on the test rig?
What kind of alternator do you have?
something doesnt sound right.
If the alternator wont put out more than 13.5 volts,
the battery will go dead as there isnt enough over 12v to charge the battery.
What were the test results of the alternator how much voltage was it producing on the test rig?
What kind of alternator do you have?