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-   -   Alternator / Voltage Regulator (http://www.clubcobra.com/forums/era-speak-bob-putnam/134408-alternator-voltage-regulator.html)

davids2toys 09-06-2015 01:01 PM
I want to put more grounds on the car. I particularly like the flat braided type. The places I found that have the sizes I like ,sell by bulk, no terminal ends.
Anybody know of a place to make custom pieces. Example: Little black wire from head to firewall. I would like to replace this wire with a a 12' piece, at least 1' wide x 1/4" thick, 3/8 terminal on one end(head) and 1/4 inch terminal on the other end (firewall). Or maybe make the hole bigger on the firewall and have 3/8 on both ends?
Anybody grounding the drivers side head? If yes, how are you running it and what are you using?
thanks...Dave

patrickt 09-06-2015 01:58 PM
Quote:
Originally Posted by davids2toys (Post 1361921)
Would the car running or not be in your calculations? Wouldn't that be part of you stuff that would be using juice?
That's with the engine off. Of course, if the engine is running, then your alternator is feeding the loads and it's not running through the circuit breaker. And I checked the fan load with the engine cold. When the engine is HOT, the fans draw more current.

davids2toys 09-06-2015 05:58 PM
Quote:
Originally Posted by patrickt (Post 1361929)
That's with the engine off. Of course, if the engine is running, then your alternator is feeding the loads and it's not running through the circuit breaker. And I checked the fan load with the engine cold. When the engine is HOT, the fans draw more current.
Never occurred to me? So that CB is only handling juice when the car is not running.
I should have paid more attention in auto shop!
OK, going out on a limb here. So your MSD box wire in not protected it if the car is running because you have it hook up to the protected side of the CB.
Why is the CB there then? What is protecting this when the car is running, the glass fuses?

DanEC 09-06-2015 06:36 PM
I bought a braided ground strap to install from my transmission to the frame from McMasters. Their selection was not real extensive but I found something to work. It had ends made up on it.

http://i125.photobucket.com/albums/p...ps90c16607.jpg

patrickt 09-06-2015 07:27 PM
Quote:
Originally Posted by davids2toys (Post 1361956)
So your MSD box wire is not protected if the car is running because you have it hook up to the protected side of the CB.
Why is the CB there then? What is protecting this when the car is running, the glass fuses?
The car will not be running if: 1) the MSD box shorts out (which will blow the internal 15 amp fuse on the MSD circuit board) or 2) the feed wire to the MSD box shorts out (because the box itself will no longer be fed. If the MSD feed wire shorts out, or if the line that leads to the ammeter shorts out, the circuit breaker will blow because the battery will try and pump lots of amps through that line even if the alternator is still turning. The glass fuses protect shorts on the load side, for the most part. Remember, almost all of the wires in your car, even the skinny little wires, will handle 50 amps for a short while . and the CB will blow if the battery dumps more than that. One of the most common wiring fires is the result of a short in the line between the alternator and the battery (the one with the ammeter in between). If this line shorts out, the CB will blow, but the alternator will still pump out its maximum for a while, and that's where the fire comes from. Now, my alternator only puts out 60 amps, so the location of the fault will spark and smoke, and maybe some plastic nearby might catch, but the wire itself can carry 60 amps with no trouble. Some of the bigger alternators are a different story.

davids2toys 09-07-2015 01:18 AM
Dan, that car is way to clean!!!
I have a similar strap at the tranny but mine is running from the frame to the tranny mount bolt. I will have to give them a look for additional straps.
thanks

davids2toys 09-07-2015 01:26 AM
Quote:
Originally Posted by patrickt (Post 1361969)
The car will not be running if: 1) the MSD box shorts out (which will blow the internal 15 amp fuse on the MSD circuit board) or 2) the feed wire to the MSD box shorts out (because the box itself will no longer be fed. If the MSD feed wire shorts out, or if the line that leads to the ammeter shorts out, the circuit breaker will blow because the battery will try and pump lots of amps through that line even if the alternator is still turning. The glass fuses protect shorts on the load side, for the most part. Remember, almost all of the wires in your car, even the skinny little wires, will handle 50 amps for a short while . and the CB will blow if the battery dumps more than that. One of the most common wiring fires is the result of a short in the line between the alternator and the battery (the one with the ammeter in between). If this line shorts out, the CB will blow, but the alternator will still pump out its maximum for a while, and that's where the fire comes from. Now, my alternator only puts out 60 amps, so the location of the fault will spark and smoke, and maybe some plastic nearby might catch, but the wire itself can carry 60 amps with no trouble. Some of the bigger alternators are a different story.
Thanks Pat. I think I actually understand what you are saying here!!
Is there a way to tell how big of an Alt you have? I know I have an external regulator and that is about it.
Dave

patrickt 09-07-2015 06:44 AM
Quote:
Originally Posted by davids2toys (Post 1361996)
Thanks Pat. I think I actually understand what you are saying here!!
Is there a way to tell how big of an Alt you have? I know I have an external regulator and that is about it.
Dave
There are two ways to tell. The hard way is to remove it and test it for maximum output current. The easy way is to look for the plate that is attached to the outside of the housing. Manufacturers of alternators conspire to always place the plate in such a way so as to make it as difficult as possible to see while just peering in to the engine bay. Stick your phone down under the alternator and snap a few pics from beneath. Then Google the model number of the alternator and it will give you the specs.

davids2toys 09-07-2015 09:57 PM
I will give it a whirl

davids2toys 09-07-2015 10:01 PM
Quote:
Originally Posted by patrickt (Post 1361811)
I added up my amperage loads on my car. With every single switch I have turned on I'm still only in the 40's. The only way I can test that circuit breaker would be to bench test it or short it out... so I'll just leave it be.;)
Maybe I'm way off here, but couldn't you use that clamp meter to measure your Real/actual amperage going thru the CB?

patrickt 09-08-2015 06:34 AM
Quote:
Originally Posted by davids2toys (Post 1362121)
Maybe I'm way off here, but couldn't you use that clamp meter to measure your Real/actual amperage going thru the CB?
Yes, with the engine off and everything turned on that would give an exact reading on the total amperage. It was just easier to add it all up in my head than to walk downstairs to the garage and actually measure it.:cool: Since all my lights are LEDs, which account for very little current, my fans and head lights are pretty much it. Of more interest is the amp draw by the fans. If you look at your SPAL data sheet, it has a nice little table that shows the different current draws based on the temperature and whether you have it as a pusher or puller. When I shut down my engine, and it is nice and hot, the current draw, as measured, is five amps or so more than when the engine is cool. Of course, the voltage is a little lower too since the alternator is not running.

davids2toys 09-08-2015 10:44 PM
Quote:
Originally Posted by patrickt (Post 1362148)
Yes, with the engine off and everything turned on that would give an exact reading on the total amperage. It was just easier to add it all up in my head than to walk downstairs to the garage and actually measure it.:cool: Since all my lights are LEDs, which account for very little current, my fans and head lights are pretty much it. Of more interest is the amp draw by the fans. If you look at your SPAL data sheet, it has a nice little table that shows the different current draws based on the temperature and whether you have it as a pusher or puller. When I shut down my engine, and it is nice and hot, the current draw, as measured, is five amps or so more than when the engine is cool. Of course, the voltage is a little lower too since the alternator is not running.
I borrowed a friend's amp tool See post #45 http://www.clubcobra.com/forums/era-...ml#post1362244
Car OFF and cold, with the fan, high beams, and wipers on I got about 15 amps going thru the CB. Seems pretty good to me?
No brake lights, horn or blinkers.
I might have to do this again. It is after midnight and I'm beat. Maybe I screwed this up...LOL

patrickt 09-09-2015 08:56 AM
Quote:
Originally Posted by davids2toys (Post 1362246)
Maybe I screwed this up...LOL
You did. There's no way that's only pulling 15 amps. If you take your headlights alone, two 60 watt bulbs is 120 watts, divide that by 12.6 volts, and you get 9.5 amps for the lights alone. I'll look at your other post on "Bad Starter" to see if I can see what you're doing wrong.

davids2toys 09-09-2015 10:12 PM
Quote:
Originally Posted by patrickt (Post 1362265)
You did. There's no way that's only pulling 15 amps. If you take your headlights alone, two 60 watt bulbs is 120 watts, divide that by 12.6 volts, and you get 9.5 amps for the lights alone. I'll look at your other post on "Bad Starter" to see if I can see what you're doing wrong.
You're right, it was either the gauge or me. I went out and re-did it this morning and it was not 15, it was 5 amps. when I saw that, I tried it on the 10 amp scale and it gave me about 2 amps. I canned the whole idea with this gauge. I went to Sears today and bought the clamp gauge you suggested. I will try again Friday or Sat. I am just putting the probe on both sides of the CB. Speaking of the CB, I got the new one today(type 3). What a cheap looking piece of crap compared to the metal auto resetting Type 1 that is in the car now. Last week I tested the resistance in the old CB and it read zero or .01ohms, I forgot. I will do the same to this new one and see what I get.
Just went out and checked it. It flashes a number for a split second and goes to 0.000 immediately. The number looks to be .750 most of the time before it flashes to zero. When I say split second I mean it. does this sound right?
In testing the CB I just went from stud to stud and disconnected no wires. . I guess my thinking was I just wanted to see what was running thru the breaker. Maybe that is why the very low reading. Please enlighten me on the Patrick procedure correct way to do this test...LOL
Dave

patrickt 09-10-2015 01:22 PM
Quote:
Originally Posted by davids2toys (Post 1362346)
In testing the CB I just went from stud to stud and disconnected no wires. I guess my thinking was I just wanted to see what was running thru the breaker. Maybe that is why the very low reading. Please enlighten me on the Patrick procedure correct way to do this test...LOL
Dave
Naaah, you're wasting your time doing it that way -- and you're only going to fool yourself with the results. Measuring resistance will only get you so far. For example, let's say you have two wires, one is a nice new fat 0 gauge battery cable and the other is a ratty old piece of copper strand the thickness of a dog hair. You get out your trusty multimeter and you check the resistance on both wires and they both show just about no resistance. Maybe the dog hair is actually a little less in ohms, who knows. What does the test tell you? Nothing. The moment you put a load on the dog hair the wire will go *poof* and you'll have an open circuit. In order to really measure a "thing" that is on an automotive circuit, be it a span of wire, a circuit breaker, a fuse, a connection, etc., you must perform a "voltage drop test." That's your next lesson after you master clamping your inductive amp meter around a wire.;)

davids2toys 09-11-2015 09:54 AM
Quote:
Originally Posted by patrickt (Post 1362397)
Naaah, you're wasting your time doing it that way -- and you're only going to fool yourself with the results. Measuring resistance will only get you so far. For example, let's say you have two wires, one is a nice new fat 0 gauge battery cable and the other is a ratty old piece of copper strand the thickness of a dog hair. You get out your trusty multimeter and you check the resistance on both wires and they both show just about no resistance. Maybe the dog hair is actually a little less in ohms, who knows. What does the test tell you? Nothing. The moment you put a load on the dog hair the wire will go *poof* and you'll have an open circuit. In order to really measure a "thing" that is on an automotive circuit, be it a span of wire, a circuit breaker, a fuse, a connection, etc., you must perform a "voltage drop test." That's your next lesson after you master clamping your inductive amp meter around a wire.;)
I wasn't measuring resistance, I was trying to measure amps going thru it:confused:

patrickt 09-11-2015 10:01 AM
Quote:
Originally Posted by davids2toys (Post 1362483)
I wasn't measuring resistance, I was trying to measure amps going thru it:confused:
You can't measure amps that way. In fact, you can't measure resistance that way either. So, put that completely out of your mind. With the circuit breaker connected, and some electrical loads running (like lights and fans) your inductive ammeter will tell you the current that is running through that circuit, but a voltage drop test will tell you if that circuit breaker, or a connection, or a wire, is creating a bottleneck -- and that's what you really want to know.

davids2toys 09-12-2015 11:43 AM
Quote:
Originally Posted by patrickt (Post 1362485)
You can't measure amps that way. In fact, you can't measure resistance that way either. So, put that completely out of your mind. With the circuit breaker connected, and some electrical loads running (like lights and fans) your inductive ammeter will tell you the current that is running through that circuit, but a voltage drop test will tell you if that circuit breaker, or a connection, or a wire, is creating a bottleneck -- and that's what you really want to know.
AYIYIYI:eek:
So what is the purpose for the ohms function on the multi-meter if it is useless. I did a quick Google search on voltage drop test and in what I do understand, it makes sense!

Grubby 09-12-2015 12:12 PM
Ohm function is great for finding opens in the circuits. A bad relay, faulty heating elements like in your stove are all easy with the OHM function.

It is very good for finding a poor connection in electrical connectors.

If you measure resistance across many electrical items and compare a known good one with a questionable part, you can usually find the problem.

I frequently use the feature when chasing electrical problems in the house or garage.

A typical quality DVM can handle 20A in series. That is enough to check most automotive circuits. Look at your fuses; most are 10A and 20A. The starter is more than 20A draw.

A good quality Fluke or other DVM is a must have if you work on cars.


John

Large Arbor 09-12-2015 02:10 PM
Hey Patrick and others,

New battery, new VR, and New Alternator and the battery is not staying charged. It was tested last week and had 800 plus cranking amps. I ran the car for 20 minutes and the battery is now reading about 9 volts with a charger on it. I took a voltage reading from the alternator when running and it read 18 V.

The only thing known drawing current is the fan. How do I diagnose this problem? Could I still have a bad VR?

Phil


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