Battery draining
10-07-2006, 12:08 AM
#91
I know I posted already about what my prob was, but here were the steps that I took.
Bad drain on battery. Sometimes on the charger it would work, sometimes it would only start off the jumper up front. Slow crank and would catch 50% of the time, the rest................yea........
Checked all interior lighting, kept battery on charger so I unplugged my hatch accessory light. (plug under the tool kit)
Checked all ground wires, ground from battery, grounds under passenger side in the fuse/relay area, grounds under drivers side (ignition key ones), ground in engine compartment, (front of car, by headlight mech) Body to engine ground, that big silver one that is on the passenger side.
Then cleaned my starter connections. They were fine.
Stereo, pulled and made sure that the head unit and amps were not connected to anything but ignition off or remote positives, and grounds were good. Had heard about the nightmares with idiots doing upgrades.
Had battery tested for 2nd time and found out that 1st test was done by old equipment, replaced battery and everything was fine.
This doesn't sound like it will fix your problem, but I felt the need to post in case others search the forums with a similar problem and this might help.
Bad drain on battery. Sometimes on the charger it would work, sometimes it would only start off the jumper up front. Slow crank and would catch 50% of the time, the rest................yea........
Checked all interior lighting, kept battery on charger so I unplugged my hatch accessory light. (plug under the tool kit)
Checked all ground wires, ground from battery, grounds under passenger side in the fuse/relay area, grounds under drivers side (ignition key ones), ground in engine compartment, (front of car, by headlight mech) Body to engine ground, that big silver one that is on the passenger side.
Then cleaned my starter connections. They were fine.
Stereo, pulled and made sure that the head unit and amps were not connected to anything but ignition off or remote positives, and grounds were good. Had heard about the nightmares with idiots doing upgrades.
Had battery tested for 2nd time and found out that 1st test was done by old equipment, replaced battery and everything was fine.
This doesn't sound like it will fix your problem, but I felt the need to post in case others search the forums with a similar problem and this might help.
10-07-2006, 03:10 AM
#92
Drifting
Thread Starter
The clouds are starting to part 
Here's the latest.
* The car was on the trickle charger for about 12 hours today.
* Removed the charger, and tested the voltage at both the battery post and the jumper. Voltage was about 12.55.
* Cleaned both battery posts, the pos cable connector, both ends of the ground strap, and the grounding point on the frame. Cleaned each in turn, testing voltage after each re-connection at the jumper to make sure I was getting a good connection before moving on to the next cleaning. Voltage maintained at around 12.5v.
* Cleaned jumper in the engine compartment. Voltage still at 12.5.
* Rolled down power windows to prepare for a buddy to help me test the car while running. This involved interior lights coming on, turning key on, lowering both windows. Tested voltage afterwards, at 12.45, but crept back up to 12.47 after a minute or so.
When buddy finally gets here I put him in the driver seat with instructions about what we're doing.
* At battery, I take an initial baseline reading, still at about 12.5v
* Key on, voltage starts to drop, but after a minute it's only at about 12.3v.
* Start car, voltage dips to the 10.0 range briefly. (The car starts easily, so this was a *very* fast measurement).
* Once running, voltage stabilizes at about 12v. Buddy notes that the generator light is on, idling at about 600rpm.
* I ask him to slowly increase the RPMs until the light goes off. At the same moment he says the light goes off, I see the voltage go to about 13.6v. He says it's about 1500 RPM.
* Turn off car.
* Repeated at the jumper post, we get exactly the same results.
* After turning on the wipers, lights and fan, at 1500 rpm, voltage stays at about 13.5v.
* Run up the RPMs to 2200, voltage stays about 13.5v.
* Relay position XV: it's a manual transmission, so there's a bridge here. I have no other bridge to swap, but if starting trouble comes back I'll pull it and clean the contacts.
So, here's my conclusion: The generator light is accurately reporting the state of the charging system. The generator works, but not optimally. It either needs new brushes, or is just worn out. My starting problem/battery drain that appeared while diagnosing the slow battery drain was mostly the result of normal power draw combined with high rpm's required for charging, a requirement that wasn't being met. Probably won't be an issue under normal operation. The car probably had the idle set high to compensate for this.
Since it's nighttime, I'll have to do the daylight driving test tomorrow morning. If the battery really does hold it's charge tonight, and it passes the 20 mile driving test tomorrow morning, I'll go on the Ojai run with the Elise guys tomorrow.
Here's the latest.* The car was on the trickle charger for about 12 hours today.
* Removed the charger, and tested the voltage at both the battery post and the jumper. Voltage was about 12.55.
* Cleaned both battery posts, the pos cable connector, both ends of the ground strap, and the grounding point on the frame. Cleaned each in turn, testing voltage after each re-connection at the jumper to make sure I was getting a good connection before moving on to the next cleaning. Voltage maintained at around 12.5v.
* Cleaned jumper in the engine compartment. Voltage still at 12.5.
* Rolled down power windows to prepare for a buddy to help me test the car while running. This involved interior lights coming on, turning key on, lowering both windows. Tested voltage afterwards, at 12.45, but crept back up to 12.47 after a minute or so.
When buddy finally gets here
I put him in the driver seat with instructions about what we're doing.* At battery, I take an initial baseline reading, still at about 12.5v
* Key on, voltage starts to drop, but after a minute it's only at about 12.3v.
* Start car, voltage dips to the 10.0 range briefly. (The car starts easily, so this was a *very* fast measurement).
* Once running, voltage stabilizes at about 12v. Buddy notes that the generator light is on, idling at about 600rpm.
* I ask him to slowly increase the RPMs until the light goes off. At the same moment he says the light goes off, I see the voltage go to about 13.6v. He says it's about 1500 RPM.
* Turn off car.
* Repeated at the jumper post, we get exactly the same results.
* After turning on the wipers, lights and fan, at 1500 rpm, voltage stays at about 13.5v.
* Run up the RPMs to 2200, voltage stays about 13.5v.
* Relay position XV: it's a manual transmission, so there's a bridge here. I have no other bridge to swap, but if starting trouble comes back I'll pull it and clean the contacts.
So, here's my conclusion: The generator light is accurately reporting the state of the charging system. The generator works, but not optimally. It either needs new brushes, or is just worn out. My starting problem/battery drain that appeared while diagnosing the slow battery drain was mostly the result of normal power draw combined with high rpm's required for charging, a requirement that wasn't being met. Probably won't be an issue under normal operation. The car probably had the idle set high to compensate for this.
Since it's nighttime, I'll have to do the daylight driving test tomorrow morning. If the battery really does hold it's charge tonight, and it passes the 20 mile driving test tomorrow morning, I'll go on the Ojai run with the Elise guys tomorrow.
10-07-2006, 04:35 AM
#93
Rennlist Member
I'm assuming that somewhere along the way, you verified that the alternator belt is tight enough.
It sounds like you've got a burnt diode in the alternator -- might want to have that bench-tested. That would likely weaken the battery over time until it finally gave up. You'll want a place that has a tester with a scope(or some other reliable means of testing for bad diodes without disassembling), not just an ampmeter like the ones they have at Kragen's. Call around and see who in your area has the right equipment for this.
BTW, do you have the cooling shroud & duct for the alternator? If not, that will cause dides & regulator to overheat and fail prematurely. Might want to look into that.
Anyway, it sounds like you're good to go on a drive, just go with caution. Pay attention to the voltage especially when sitting in traffic, when the aux. fan comes on.
It sounds like you've got a burnt diode in the alternator -- might want to have that bench-tested. That would likely weaken the battery over time until it finally gave up. You'll want a place that has a tester with a scope(or some other reliable means of testing for bad diodes without disassembling), not just an ampmeter like the ones they have at Kragen's. Call around and see who in your area has the right equipment for this.
BTW, do you have the cooling shroud & duct for the alternator? If not, that will cause dides & regulator to overheat and fail prematurely. Might want to look into that.
Anyway, it sounds like you're good to go on a drive, just go with caution. Pay attention to the voltage especially when sitting in traffic, when the aux. fan comes on.
10-07-2006, 12:32 PM
#94
"So, here's my conclusion: The generator light is accurately reporting the state of the charging system. The generator works, but not optimally."
How can you make the conclusion that the alternator (not generator) is not optimal?
1. You didn't measure its charging current (should be ~ 60 - 80 amp not fully loaded) .
2. The 13.6 volts measured is normal for the early & late 928 alternators.
The Paris-Rhone ones ('82/'83) are a little higher 13.9 - 14.2.
3. The alt light goes out and doesn't glow (bad diode) as the RPMs increase.
Furthermore, unless I missed it, it appears the current drain of 150 ma has NOT been resolved.
The current drain should be less than 60ma for reasonable car non-use time period.
Ideally 30-40ma would be better and is generally the case for older cars with less electronics.
How can you make the conclusion that the alternator (not generator) is not optimal?
1. You didn't measure its charging current (should be ~ 60 - 80 amp not fully loaded) .
2. The 13.6 volts measured is normal for the early & late 928 alternators.
The Paris-Rhone ones ('82/'83) are a little higher 13.9 - 14.2.
3. The alt light goes out and doesn't glow (bad diode) as the RPMs increase.
Furthermore, unless I missed it, it appears the current drain of 150 ma has NOT been resolved.
The current drain should be less than 60ma for reasonable car non-use time period.
Ideally 30-40ma would be better and is generally the case for older cars with less electronics.
10-07-2006, 01:11 PM
#95
Drifting
Thread Starter
Originally Posted by Lorenfb
How can you make the conclusion that the alternator (not generator) is not optimal?
But I stated it here so that I could be corrected.
Originally Posted by Lorenfb
Furthermore, unless I missed it, it appears the current drain of 150 ma has NOT been resolved.
The current drain should be less than 60ma for reasonable car non-use time period.
Ideally 30-40ma would be better and is generally the case for older cars with less electronics.
The current drain should be less than 60ma for reasonable car non-use time period.
Ideally 30-40ma would be better and is generally the case for older cars with less electronics.
Originally Posted by SharkSkin
BTW, do you have the cooling shroud & duct for the alternator? If not, that will cause dides & regulator to overheat and fail prematurely. Might want to look into that.
10-07-2006, 01:19 PM
#96
Rennlist Member
Originally Posted by bronto
OK, a relatively uninformed conclusion
But I stated it here so that I could be corrected.
Yes, you missed it. It was a 3rd party stereo amp wired into one of the main power feeds into the fuse panel. Pulling the fuse in the amp power wire killed the 150 amp power draw.
Doc points out that this model has a generator, not an alternator. Does that change your ideas about shroud, diodes, etc.? I don't know what the shroud looks like, so I'mnot sure how to answer your question.
But I stated it here so that I could be corrected.
Yes, you missed it. It was a 3rd party stereo amp wired into one of the main power feeds into the fuse panel. Pulling the fuse in the amp power wire killed the 150 amp power draw.
Doc points out that this model has a generator, not an alternator. Does that change your ideas about shroud, diodes, etc.? I don't know what the shroud looks like, so I'mnot sure how to answer your question.
Generators are '50s design; you should have an altenator which has 3 diodes in it coverting the AC current to DC as part of the rectification circuitry...........if one of the diodes is dead your not getting full output. If in doubt remove it and have it tested as described.
10-07-2006, 01:30 PM
#97
Rennlist Member
Malcom's right. I passed over that because it didn't seem important... but it's an alternator. The correct unit should have 6 diodes, like in the pic:
More info here.
One thing I discovered, is that the 928 alternator spins unusually slow due to the unusually small crank pulley. If you had the wrong alternator installed at some point(Mark Anderson, 928I, tells me an 80's Audi 5000 alt. is a common swap) that would explain the no-charge-at-idle symptoms; most alternators are not designed to charge at such a low speed.
So, your alternator could be fine, just the wrong one for the application. But if it's the correct one, your symptoms sound like a blown diode.
More info here.
One thing I discovered, is that the 928 alternator spins unusually slow due to the unusually small crank pulley. If you had the wrong alternator installed at some point(Mark Anderson, 928I, tells me an 80's Audi 5000 alt. is a common swap) that would explain the no-charge-at-idle symptoms; most alternators are not designed to charge at such a low speed.
So, your alternator could be fine, just the wrong one for the application. But if it's the correct one, your symptoms sound like a blown diode.
Last edited by SharkSkin; 10-07-2006 at 01:55 PM. Reason: Typo
10-07-2006, 01:51 PM
#98
Rennlist Member
Correct Dave; my diode 'wheatstone bridge' circuitry is a little rusty.
Perhaps, given the small size of pulley, is why the belt is so tight..........irregardless good to check model of alternator installed and then have its o/p checked; both voltage and current.
Perhaps, given the small size of pulley, is why the belt is so tight..........irregardless good to check model of alternator installed and then have its o/p checked; both voltage and current.
10-07-2006, 02:01 PM
#99
Rennlist Member
Malcom, it's an easy mistake to make -- most alternators these days have 3 diodes. I think the small crank pulley was intended to reduce parasitic HP loss. If anything, it should require less belt tension than one with a higher ratio.
BTW, go to the link that I provided below the pic in my previous post. There are pics of the shroud and duct there.
BTW, go to the link that I provided below the pic in my previous post. There are pics of the shroud and duct there.
10-07-2006, 02:14 PM
#100
Drifting
Thread Starter
20 mile test = passed.
I kept a sharp eye on the voltage meter during the drive, and it stayed a bit above 12v the whole time. When I got back, the idle was low - about 600 - and the voltage light did not come on. In fact, after I left the parking lot it did not come on again. After getting back I tested voltage again and while running it was 13.5 and while not running it was 12.77. I'll test it again when I get to Ojai in about 2 hours.
I kept a sharp eye on the voltage meter during the drive, and it stayed a bit above 12v the whole time. When I got back, the idle was low - about 600 - and the voltage light did not come on. In fact, after I left the parking lot it did not come on again. After getting back I tested voltage again and while running it was 13.5 and while not running it was 12.77. I'll test it again when I get to Ojai in about 2 hours.
10-07-2006, 06:12 PM
#101
"So, your alternator could be fine, just the wrong one for the application. But if it's the correct one, your symptoms sound like a blown diode."
The alt in picture is the '82/'83 Paris-Rhone, a TOTAL piece a JUNK. This one and its "brother"
used on the 911SC (same years) are both junk. The diode plates are TOTALLY inadequate to
handle (dissipate) the heat and the diodes need to be 2/phase to handle the current.
The alt in picture is the '82/'83 Paris-Rhone, a TOTAL piece a JUNK. This one and its "brother"
used on the 911SC (same years) are both junk. The diode plates are TOTALLY inadequate to
handle (dissipate) the heat and the diodes need to be 2/phase to handle the current.
10-07-2006, 06:46 PM
#102
Since this started when you were in the fuse panel, I would check the alternator exciter circuit for low voltage. Start with the fuses for the instrument panel lights. Also check the exciter wire connection on the alternator.
Dennis
Dennis
10-07-2006, 08:10 PM
#103
Drifting
Thread Starter
Originally Posted by Lorenfb
The alt in picture is the '82/'83 Paris-Rhone, a TOTAL piece a JUNK. This one and its "brother"
used on the 911SC (same years) are both junk. The diode plates are TOTALLY inadequate to
handle (dissipate) the heat and the diodes need to be 2/phase to handle the current.
used on the 911SC (same years) are both junk. The diode plates are TOTALLY inadequate to
handle (dissipate) the heat and the diodes need to be 2/phase to handle the current.
10-07-2006, 08:16 PM
#104
Drifting
Thread Starter
Back from Ojai. About 120 miles round trip .. a fantastic drive, BTW. If you ever have a chance to drive HWY 150 from Santa Barbara and continue up HWY 33 past Ojai, it's well worth the trip. This was the general area of the Day fire that was contained just last week. No visual evidence of it was seen, but there were places where you could smell burnt charcoal.
I kept a carefull eye on my voltage meter. At no time - including the first start out of my place - did the light come on. The entire time, the needle read a fraction above or below 12v. The trip involved 4 engine starts, all with no trouble. When I got mack home, I drove the last couple of miles with the lights on just to put a load on it. With the engine still running, I measured the voltage at the jumper. With the lights still on, it was 12.55v. With the lights off, it was 13.25v. This was at the low idle I mentioned before, maybe 600 rpm.
I kept a carefull eye on my voltage meter. At no time - including the first start out of my place - did the light come on. The entire time, the needle read a fraction above or below 12v. The trip involved 4 engine starts, all with no trouble. When I got mack home, I drove the last couple of miles with the lights on just to put a load on it. With the engine still running, I measured the voltage at the jumper. With the lights still on, it was 12.55v. With the lights off, it was 13.25v. This was at the low idle I mentioned before, maybe 600 rpm.
10-07-2006, 08:43 PM
#105
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bronto... sounds better & better.
Did you take rte.33 over the summit (Pine Mtn.) into Cuyama
valley and make a circuit back to S" Barb'a ??
Yes, the Day fire aroma travels... it was NE of Wheeler Springs/Ojai/
Pine Mtn. Glad it didn't turn that nice country (& people/places) to ash.
G'luck.
Did you take rte.33 over the summit (Pine Mtn.) into Cuyama
valley and make a circuit back to S" Barb'a ??
Yes, the Day fire aroma travels... it was NE of Wheeler Springs/Ojai/
Pine Mtn. Glad it didn't turn that nice country (& people/places) to ash.
G'luck.