Alternator / Voltage Regulator

[davids2toys]

Originally Posted by patrickt

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.

Would the car running or not be in your calculations? Wouldn't that be part of you stuff that would be using juice?

[patrickt]

Originally Posted by davids2toys

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]

Originally Posted by patrickt

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]

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.

[patrickt]

Originally Posted by davids2toys

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 <pun>. 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]

Originally Posted by patrickt

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 <pun>. 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]

Originally Posted by davids2toys

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.