Alternator Wiring Question
Race Director
Joined: Apr 2007
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From: South Western Ontario
Ohh., "German Engineered". Like it's special some how lol. If you haven't run into "German Engineered" which makes no sense and works worse than other similar products then you haven't been around it much. I've seen things at work that make no logical sense. Others have too. Enough that "German Engineered" means nothing to me other that it's probably overly convoluted and stupidly priced.
Last edited by lionelhutz; Jul 15, 2017 at 11:52 PM.
Race Director
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From: Tampa, Florida
My BMW drives me crazy with its 'over engineered' features.
Instructor
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From: jim thorpe pa
where to put this? And aother that is on with the key, the fuse box by our feet is insane
Safety Car
Joined: May 2001
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From: Fairfax Virginia
Bigger Alternators are great on older Corvettes
The biggest issue that nobody here mentioned is that on most cars the battery is in the engine bay and on our older Corvettes it is far away from the engine bay. When the battery is close I would run it there as well, but if the battery is farther away I choose to go to the starter.
On my 1968 C3 I have a 120 amp alternator that is wired to the starter directly from the alternator output terminal with a 4 gauge welding cable wire. It was easy to run and connect it this way. I have a 1/0 welding cable made into a battery cable connecting the battery to the starter.
If I had 11.9 volts dc with everything on at night I would assume that the alternator pulley is the wrong size. You need to spin it a bit faster. If that doesn't work, it is probably the regulator. Most modern alternators can put out a significant amount of amperage at idle.
Good luck with your electrical system and may it keep you "Charged"!
On my 1968 C3 I have a 120 amp alternator that is wired to the starter directly from the alternator output terminal with a 4 gauge welding cable wire. It was easy to run and connect it this way. I have a 1/0 welding cable made into a battery cable connecting the battery to the starter.
If I had 11.9 volts dc with everything on at night I would assume that the alternator pulley is the wrong size. You need to spin it a bit faster. If that doesn't work, it is probably the regulator. Most modern alternators can put out a significant amount of amperage at idle.
Good luck with your electrical system and may it keep you "Charged"!
Le Mans Master
Joined: May 2003
Posts: 8,877
Likes: 3,556
From: Fernandina Beach FL
2023 Restomod of the Year finalist
2020 C3 of the Year Winner - Modified
The biggest issue that nobody here mentioned is that on most cars the battery is in the engine bay and on our older Corvettes it is far away from the engine bay. When the battery is close I would run it there as well, but if the battery is farther away I choose to go to the starter.
On my 1968 C3 I have a 120 amp alternator that is wired to the starter directly from the alternator output terminal with a 4 gauge welding cable wire. It was easy to run and connect it this way. I have a 1/0 welding cable made into a battery cable connecting the battery to the starter.
On my 1968 C3 I have a 120 amp alternator that is wired to the starter directly from the alternator output terminal with a 4 gauge welding cable wire. It was easy to run and connect it this way. I have a 1/0 welding cable made into a battery cable connecting the battery to the starter.
The battery is not under the hood on a lot of German cars....and the C7...
The "German engineering" behind this- as it stabilizes the temperature better.
I really did stupid wiring- I ran 1/0 as well- from the starter to the battery and 1/0 to the alternator(custom built Nippon Denso- do realize it's not German- but using the smallest German pulley I could find) Then 4 gauge right off the battery (power AND ground- I know, makes no sense-just wanted to be sure the wipers AND the gauge lights work...) for the rest of the car.
And another stupid German idea- since the battery is inside the cabin- why not put a jumper cable terminal near the starter- where most of the power is needed AND easy to get to...dang Germans...
Got this off a BMW 750iL-
Has a cover- that's not on in this picture
Le Mans Master
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From: Fernandina Beach FL
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Le Mans Master
Joined: Dec 2006
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So,
Just for fun, I measured from the alternator to the starter.
Approx. 6'.
I measured from the alternator to the battery. '
Approx. 6'.
Alternator ground, which the 81 has, runs back to the battery ground cable on the rear cross member.
Approx. 6'.
I "assume" the VD would be identical.
Given the battery cable can power the car while starting, with the starter off, it should power the car with very little VD.
I need to break out my power probe, and measure some stuff.
BTW, I had a few beers.
Just for fun, I measured from the alternator to the starter.
Approx. 6'.
I measured from the alternator to the battery. '
Approx. 6'.
Alternator ground, which the 81 has, runs back to the battery ground cable on the rear cross member.
Approx. 6'.
I "assume" the VD would be identical.
Given the battery cable can power the car while starting, with the starter off, it should power the car with very little VD.
I need to break out my power probe, and measure some stuff.
BTW, I had a few beers.
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Race Director
Joined: Apr 2007
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From: South Western Ontario
At least you explained why you can't use a tape measure...
Battery to starter cable is about 9' so alternator to starter IS NOT 6'. If it takes 6' to get from the alternator to starter which is ahead of the driver how the hell can it also take 6' to get to the battery behind the driver?
Try drinking less?
Battery to starter cable is about 9' so alternator to starter IS NOT 6'. If it takes 6' to get from the alternator to starter which is ahead of the driver how the hell can it also take 6' to get to the battery behind the driver?
Try drinking less?
Le Mans Master
Joined: Dec 2006
Posts: 8,837
Likes: 1,028
At least you explained why you can't use a tape measure...
Battery to starter cable is about 9' so alternator to starter IS NOT 6'. If it takes 6' to get from the alternator to starter which is ahead of the driver how the hell can it also take 6' to get to the battery behind the driver?
Try drinking less?
Battery to starter cable is about 9' so alternator to starter IS NOT 6'. If it takes 6' to get from the alternator to starter which is ahead of the driver how the hell can it also take 6' to get to the battery behind the driver?
Try drinking less?
Fender to fender is about 4'
Firewall to battery box is about 4'
It still works out about the same.
Le Mans Master
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From: Fernandina Beach FL
2023 Restomod of the Year finalist
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Le Mans Master
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Okay. 1.2 meters either way.
I am pissed because I saved the original old #10 alternator to battery wire.
It had a fusable link not shown in any book, at the battery end. Crimped, soldered, 1 wrap of friction tape, and hidden inside the plastic looming.
If it blew, you would never known it was there.
I am pissed because I saved the original old #10 alternator to battery wire.
It had a fusable link not shown in any book, at the battery end. Crimped, soldered, 1 wrap of friction tape, and hidden inside the plastic looming.
If it blew, you would never known it was there.
Race Director
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From: South Western Ontario
I've read anything from 8' to 9', and people buying a 10' piece to upgrade and cutting about 1' off. So, something like 95" as the minimum length is realistic.
SO,
The original battery to starter cable is not even close to only 55".
There is no way a cable from the alternator to starter solenoid will be 6'.
There is no way a cable from the alternator to the battery will be the same length as a cable from the alternator to the starter solenoid.
Wait, maybe you're measuring some other car with the battery up front????
Also, if you MUST run every wire right to the positive battery post, then don't forget about the new wire coming from the battery back to the front of the car....
Le Mans Master
Joined: Dec 2006
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I've read anything from 8' to 9', and people buying a 10' piece to upgrade and cutting about 1' off. So, something like 95" as the minimum length is realistic.
SO,
The original battery to starter cable is not even close to only 55".
There is no way a cable from the alternator to starter solenoid will be 6'.
There is no way a cable from the alternator to the battery will be the same length as a cable from the alternator to the starter solenoid.
Wait, maybe you're measuring some other car with the battery up front????
Also, if you MUST run every wire right to the positive battery post, then don't forget about the new wire coming from the battery back to the front of the car....
The starter cable is 55", fact, not fiction.
It departs the battery compartment via a grommet, goes right up the drive shaft tunnel, and kicks over to the starter.
The alternator output wire leaves the alt. lug, goes down the fender at 45* angle, enters the frame rail, and exits the frame rail right inboard of the T/A pocket, and enters the battery box via a grommet.
All power departs via the starter lug, just as stock.
I do not understand why you would argue with facts.
Measure your car and see.
GM designed it this way, not me.
Race Director
Joined: Apr 2007
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From: South Western Ontario
GM routed the wires but not using the lengths you posted. Still, since you want to make it personal about owning a C3 and how you have one then why don't you prove it? Spitballing guesses while you're drinking doesn't prove anything.
I was going to measure the main cable on Dad's car, but I didn't see him today. I found posts with the stock main cable length as measured posted by 2 different reliable members here so I don't really need to. 92" center to center of the holes in each terminal end. The floor grommet is 23" from the battery end too.
55" - 23" = 32". Didn't you say the firewall to battery was 48"??? Heck, even if there was only 1' of cable in the battery compartment 55" - 12" = 43" which doesn't compute with your numbers....
I was going to measure the main cable on Dad's car, but I didn't see him today. I found posts with the stock main cable length as measured posted by 2 different reliable members here so I don't really need to. 92" center to center of the holes in each terminal end. The floor grommet is 23" from the battery end too.
55" - 23" = 32". Didn't you say the firewall to battery was 48"??? Heck, even if there was only 1' of cable in the battery compartment 55" - 12" = 43" which doesn't compute with your numbers....
Last edited by lionelhutz; Jul 17, 2017 at 07:50 PM.
Le Mans Master
Joined: May 2003
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From: Fernandina Beach FL
2023 Restomod of the Year finalist
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I was going to measure the main cable on Dad's car, but I didn't see him today. I found posts with the stock main cable length as measured posted by 2 different reliable members here so I don't really need to. 92" center to center of the holes in each terminal end. The floor grommet is 23" from the battery end too.
Like the length of a battery cable?
Le Mans Master
Joined: Dec 2006
Posts: 8,837
Likes: 1,028
GM routed the wires but not using the lengths you posted. Still, since you want to make it personal about owning a C3 and how you have one then why don't you prove it? Spitballing guesses while you're drinking doesn't prove anything.
I was going to measure the main cable on Dad's car, but I didn't see him today. I found posts with the stock main cable length as measured posted by 2 different reliable members here so I don't really need to. 92" center to center of the holes in each terminal end. The floor grommet is 23" from the battery end too.
55" - 23" = 32". Didn't you say the firewall to battery was 48"??? Heck, even if there was only 1' of cable in the battery compartment 55" - 12" = 43" which doesn't compute with your numbers....
I was going to measure the main cable on Dad's car, but I didn't see him today. I found posts with the stock main cable length as measured posted by 2 different reliable members here so I don't really need to. 92" center to center of the holes in each terminal end. The floor grommet is 23" from the battery end too.
55" - 23" = 32". Didn't you say the firewall to battery was 48"??? Heck, even if there was only 1' of cable in the battery compartment 55" - 12" = 43" which doesn't compute with your numbers....
My question boils down to this:
Why did GM, in 1981, when they utilized an ECM, did they use this:
And run the alternator output to the battery directly?
Your quite insistent that its dumb engineering, too costly, and has no useful purpose.
Maybe they did it before BMW.
For the fusable link fans, there is one inside that tubing with a ground wire, just before the wires emerge. Kinda blows the "free air" rule out the window.
Race Director
Joined: Apr 2007
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From: South Western Ontario
The battery sits right beside the REAR u-joint. Rear u-joint to bellhousing face on the engine is about 57" on the C3. How can a cable make that run in 55" after the required extra to get from the battery compartment to the tunnel, route around the tunnel, then from the bellhousing face to the starter?
My question boils down to this:
Why did GM, in 1981, when they utilized an ECM, did they use this:
Attachment 48114688
And run the alternator output to the battery directly?
Why did GM, in 1981, when they utilized an ECM, did they use this:
Attachment 48114688
And run the alternator output to the battery directly?
The main cable at the starter end will have <0.2V fluctuation during normal operation considering EFI and electric fans are added to the car. If your electronics can't withstand 0.2V of fluctuation then they are a crappy design.
Why don't you explain why they ran an alternator ground when there are 100's of millions of other GM's that just use the alternator brackets and engine block to ground the alternator. The main engine grounding cables on the C3 make that extra ground wire pointless. You can't force the current to go down that wire just because it's there...
Last edited by lionelhutz; Jul 17, 2017 at 09:38 PM.
Le Mans Master
Joined: Dec 2006
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The math is just under 8'.
The battery sits right beside the REAR u-joint. Rear u-joint to bellhousing face on the engine is about 57" on the C3. How can a cable make that run in 55" after the required extra to get from the battery compartment to the tunnel, route around the tunnel, then from the bellhousing face to the starter?
I didn't design it so how would I know why they did it? You want me to make up something like you did for the wire lengths to get from the starter to battery and alternator to battery?
The main cable at the starter end will have <0.2V fluctuation during normal operation considering EFI and electric fans are added to the car. If your electronics can't withstand 0.2V of fluctuation then they are a crappy design.
The battery sits right beside the REAR u-joint. Rear u-joint to bellhousing face on the engine is about 57" on the C3. How can a cable make that run in 55" after the required extra to get from the battery compartment to the tunnel, route around the tunnel, then from the bellhousing face to the starter?
I didn't design it so how would I know why they did it? You want me to make up something like you did for the wire lengths to get from the starter to battery and alternator to battery?
The main cable at the starter end will have <0.2V fluctuation during normal operation considering EFI and electric fans are added to the car. If your electronics can't withstand 0.2V of fluctuation then they are a crappy design.
BTW, I pulled the 55" off of NAPA web site. Don't buy their cable. Lol
Last edited by Big2Bird; Jul 17, 2017 at 09:48 PM.
Le Mans Master
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From: Fernandina Beach FL
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Richard
Last edited by Richard454; Jul 17, 2017 at 10:14 PM.