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> The alternator replacement thread, Fixed!
VaccaRabite
post Aug 12 2018, 07:07 PM
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Waiting on the side of the road for a flatbed to take me home.

Engine ran great. Charging system not so much. Driving along. Lights started going dim. Car started bucking. Only 5 miles to home but it wasn’t going to make it, and no shoulders to pull over safe on the little farm roads. So I pulled into a spot I knew of and shut it down and parked it and now I wait.

McMark had said earlier he wasn’t sure about the charging system. But the alt light was not on and no issues before now.

So. What’s the alternator I need to buy?
Maybe a new VR as well?
I guess I should test the battery and make sure it’s okay too.

Zach
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VaccaRabite
post Aug 27 2018, 05:04 PM
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I got Epstien's package in the mail today. So that was a good excuse to fiddle with the car after work.

I tested continuity from the alternator to the engine block and to the body. Very strong continuity, about one ohm resistance from the alternator case to the body. From the transmission to the body was basically zero resistance (there was a very small number on the screen of my meter). So, gounding was not an issue.

I replaced the board with a new one from Mark and put everything back. I am using the new solid state VR.

Started the car, and was measuring 12.6 volts at the battery on the meter at warm idle. Unplugged the VR and it dropped to 12 volts on the battery, and the engine idle speed increased slightly. So the car IS charging at idle.

Bring the throttle up to 4K rpm, and voltage dropped to 12.05 volts. So back to its old tricks. With all my lights on (driving lights, head lights, flashers) and the engine at 4K rpm I was only making 11.3 volts at the battery.

Unplugged the VR again and shorted DF to D+ and was making 14 volts at idle and the engine idle lowered noticeably.

I had my laptop plugged in and talking to the ECU, and the ECU is seeing about .6 volts less then my meter is seeing across the battery terminals. The tuning software was occationaly flashing the red "charging" flag.

At this place, I have replaced:
Alternator
VR (several times)
relay board
Alternator harness

I have confirmed that all the engine compartment grounds are in good shape.

About the only thing I can think to do at this time is add a ground wire from the alt to the engine case, but I really doubt that's my issue at this point. :-/

The other option is a bigger alternator (70 amp maybe?).

Is it at all possible that my battery is the issue? I'm using a Odessey race battery.

Thinking out loud. Is it at all possible that the alternator I put in (that I got from @bdstone914 ) was internally regulated? Would double regulation do what I am seeing? How would I tell?

@spoke
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Zach
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Spoke
post Aug 28 2018, 04:53 AM
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QUOTE(Vacca Rabite @ Aug 27 2018, 07:04 PM) *
one ohm resistance from the alternator case to the body. From the transmission to the body was basically zero resistance (there was a very small number on the screen of my meter). So, gounding was not an issue.


If you're measuring one ohm between the alt case and engine block, this should be considered a very large resistance. If indeed you have 1 ohm resistance between alt case and engine block, this would account for strange behavior and not as much voltage applied to the battery.

Ohms law is V = I x R. With 1 ohm if there is 1 amp of charging current, there will be 1V drop in a system where the difference between 1-2V is huge.

You can test to see if you have a voltage drop from alt case to chassis by measuring at the VR from D- to chassis. See the schematic below where D- at the VR is connected to the alt case. Short D+ to DF; start the car and measure voltage from D- to chassis. There's a chassis stud right by the relay board. You should read zero volts or near there.


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Posts in this topic
Vacca Rabite   The alternator replacement thread   Aug 12 2018, 07:07 PM
FL 000   That sucks, I know the feeling. Same thing happene...   Aug 12 2018, 07:26 PM
ClayPerrine   Did you check the generator light bulb? The wrong...   Aug 12 2018, 07:32 PM
Vacca Rabite   Bruce Stone is the man and has an alternator for m...   Aug 12 2018, 07:57 PM
bdstone914   Bruce Stone is the man and has an alternator for ...   Aug 12 2018, 10:50 PM
bobboinski   Did you check the generator light bulb? The wron...   Aug 12 2018, 07:58 PM
ClayPerrine   Did you check the generator light bulb? The wro...   Aug 12 2018, 08:06 PM
Mark Henry   :agree: The alternator idiot light was on when you...   Aug 12 2018, 08:25 PM
Vacca Rabite   Yup. Red light was on when I turned the key and we...   Aug 12 2018, 08:30 PM
Mark Henry   Yup. Red light was on when I turned the key and w...   Aug 12 2018, 08:43 PM
Unobtanium-inc   I hate the site of a pretty Porsche being dragged,...   Aug 12 2018, 08:31 PM
Vacca Rabite   I probably would have made it home if I had not...   Aug 12 2018, 08:39 PM
bobboinski   Yup. Red light was on when I turned the key and ...   Aug 12 2018, 08:50 PM
r_towle   get an amp gauge. Bummer, but you are so close ma...   Aug 12 2018, 09:03 PM
Spoke   I wouldn't put in a new alternator until you k...   Aug 12 2018, 09:04 PM
Amphicar770   I wouldn't put in a new alternator until you ...   Aug 13 2018, 06:09 AM
Unobtanium-inc   Ouch! If you drive older cars, AAA Platinum...   Aug 13 2018, 06:47 AM
bdstone914   I wouldn't put in a new alternator until you ...   Aug 13 2018, 08:10 AM
Dave_Darling   I had a VR that came unplugged while I was driving...   Aug 12 2018, 10:46 PM
dr914@autoatlanta.com   yup you ran out of juice, would check the belt tig...   Aug 13 2018, 06:58 AM
Vacca Rabite   I have AAA gold so my tow was covered. As I gain c...   Aug 13 2018, 08:19 AM
1adam12   I have AAA gold so my tow was covered. As I gain ...   Aug 13 2018, 11:26 AM
mepstein   I hope the house is ok. We had flooding in SE PA. ...   Aug 13 2018, 08:34 AM
Vacca Rabite   I hope the house is ok. We had flooding in SE PA....   Aug 13 2018, 09:12 AM
Vacca Rabite   Just did Spokes test of shorting DF and D+. Batte...   Aug 13 2018, 09:09 AM
ClayPerrine   Just did Spokes test of shorting DF and D+. Batt...   Aug 13 2018, 12:16 PM
Vacca Rabite   A Bosch alternator is a B circuit alternator. ...   Aug 13 2018, 12:37 PM
ClayPerrine   A Bosch alternator is a B circuit alternator. ...   Aug 13 2018, 12:45 PM
Vacca Rabite   Electrician for the house will be here in a few mi...   Aug 13 2018, 11:39 AM
914_teener   So was a battery charger plugged in and hooked up ...   Aug 13 2018, 12:27 PM
Vacca Rabite   So was a battery charger plugged in and hooked up...   Aug 13 2018, 12:31 PM
Vacca Rabite   So, new alt, VR and harness are all on order. Hop...   Aug 14 2018, 07:32 AM
90quattrocoupe   Nothing to do with the car, but if your GFI plug g...   Aug 14 2018, 11:21 AM
914_teener   Check the ignition switch.   Aug 14 2018, 12:34 PM
Vacca Rabite   Tonight I put the new alternator, harness and VR i...   Aug 18 2018, 07:59 PM
Spoke   12.89V at idle after the engine is warmed up or ri...   Aug 18 2018, 08:08 PM
Vacca Rabite   12.89V at idle after the engine is warmed up or r...   Aug 18 2018, 08:10 PM
Spoke   It sounds ok so far. How many times did you rev th...   Aug 18 2018, 08:48 PM
Vacca Rabite   System still isn’t charging right. I drove the ...   Aug 20 2018, 04:07 PM
MarkV   A fully charged car battery should be 12.6 volts s...   Aug 20 2018, 05:04 PM
904svo   Made sure you have the correct bulb (not a led ) i...   Aug 20 2018, 05:05 PM
Vacca Rabite   Made sure you have the correct bulb (not a led ) ...   Aug 20 2018, 06:16 PM
Robnxious   I just got done running this issue down as well my...   Aug 20 2018, 08:01 PM
MarkV   Years ago when I thought my mechanical VR was goin...   Aug 20 2018, 10:33 PM
MarkV   Adjustable: https://www.ebay.com/itm/NEW-ALTERNAT...   Aug 20 2018, 10:36 PM
Vacca Rabite   I bought one of the solid state pig-tailed voltage...   Aug 21 2018, 07:10 AM
plas76targa   Zach, This issue was the first ‘problem’ i exp...   Aug 21 2018, 08:29 AM
Vacca Rabite   Well, the new solid state VR did nothing. I am for...   Aug 22 2018, 04:44 PM
mepstein   Well, the new solid state VR did nothing. I am fo...   Aug 22 2018, 08:33 PM
Vacca Rabite   If you need another board, just pm me your addres...   Aug 22 2018, 09:36 PM
904svo   With the engine running measure for voltage betwee...   Aug 22 2018, 06:52 PM
Spoke   While you have the relay board out, measure the re...   Aug 22 2018, 07:54 PM
Vacca Rabite   While you have the relay board out, measure the r...   Aug 22 2018, 09:34 PM
Spoke   I did in fact powder coat the shroud and tins. Th...   Aug 23 2018, 04:42 AM
Vacca Rabite   I got Epstien's package in the mail today. So...   Aug 27 2018, 05:04 PM
Spoke   one ohm resistance from the alternator case to the...   Aug 28 2018, 04:53 AM
Vacca Rabite   EVERYTHING seems to be pointing to the voltage reg...   Aug 27 2018, 05:09 PM
MarkV   Well I am stumped. :confused: Idle at 12.6 vol...   Aug 27 2018, 07:57 PM
904svo   just a WAG try cleaning fuse #9 (both sides) this ...   Aug 27 2018, 09:40 PM
McMark   I can't remember... Is your alternator harnes...   Aug 28 2018, 05:16 AM
Vacca Rabite   I can't remember... Is your alternator harne...   Aug 28 2018, 07:35 AM
jarodswordmaster   I can't remember... Is your alternator harn...   Sep 5 2018, 05:56 AM
VaccaRabite   [quote name='Vacca Rabite' post='2643317' date='A...   Sep 5 2018, 06:37 AM
VaccaRabite   I got a new battery. Not really any change over t...   Sep 7 2018, 02:14 PM
rjames   Watching this thread rabidly as my charging system...   Sep 7 2018, 02:48 PM
worn   I got a new battery. Not really any change over ...   Sep 7 2018, 04:26 PM
Spoke   I got a new battery. Not really any change over ...   Sep 7 2018, 09:50 PM
FourBlades   Does the charging problem only happen when the lig...   Sep 7 2018, 07:36 PM
jarodswordmaster   I can't get any charge out of my alternator wi...   Sep 7 2018, 09:26 PM
Spoke   I can't get any charge out of my alternator w...   Sep 7 2018, 09:58 PM
jarodswordmaster   I can't get any charge out of my alternator ...   Sep 8 2018, 08:41 AM
Spoke   [quote name='Spoke' post='2646638' date='Sep 7 20...   Sep 8 2018, 08:48 AM
jarodswordmaster   [quote name='Spoke' post='2646638' date='Sep 7 2...   Sep 8 2018, 08:59 AM
VaccaRabite   I’m back to grounds. And I’m going to put a n...   Sep 8 2018, 03:06 PM
Spoke   I’m back to grounds. And I’m going to put a ...   Sep 8 2018, 04:13 PM
VaccaRabite   Goddamn happy dance. 14 volts at idle. 14 volts ...   Sep 8 2018, 05:17 PM
Spoke   Goddamn happy dance. 14 volts at idle. 14 volts...   Sep 8 2018, 10:06 PM
ClayPerrine   Goddamn happy dance. 14 volts at idle. 14 volts...   Sep 9 2018, 05:34 AM
bdstone914   Zach, Are your alternator mounting brackets pain...   Sep 9 2018, 08:53 AM
VaccaRabite   Zach, Are your alternator mounting brackets pai...   Sep 9 2018, 02:50 PM
Spoke   Damn, that was a tough one. Still don’t know wh...   Sep 9 2018, 11:26 AM
VaccaRabite   I took apart an engine once and the alternator h...   Sep 9 2018, 03:41 PM
worn   Goddamn happy dance. 14 volts at idle. 14 volts...   Sep 9 2018, 06:56 PM
VaccaRabite   I’m going to put the race battery back in and ch...   Sep 8 2018, 05:20 PM


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