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Sorry Jeff, too damn cold here the last few daze, and other issues running wild....and having just put the 3rd alt in there, I let it fail first.....be a while, I hope.....I did use a CS144 on a camper I did some dozen years ago...feeding a marine deep cycle for the inverter, as well as the 24 series for starting....
but these daze my spine and other arthritic areas just slo my enthusiasm to nothing anymore...damnit....
Hey buddy. No hurry in this quest.
We just need volunteer #2.
Mike>? Do you have access to a scope?
I have this scope that plugs into my laptop. Ive only used it a few times but it seems to work. Measure the voltage ripple at alternator output and bat neg ?
I have this scope that plugs into my laptop. Ive only used it a few times but it seems to work. Measure the voltage ripple at alternator output and bat neg ?
Sure. See post #5. The more results we can have, the more conclusive.
Here's my weapon of choice lately from EBAY for about $45. It's a DSO168 portable digital storage scope. 20Mhz bandwidth, no laptop required.
I looked at small hand held scopes too. I probably should have grabbed one of those instead of the laptop version.
I just got a dc clamp on amp meter. It was cool to see how many amps my c3 starter and headlights draw.
I have done quite a bit of automotive wiring repair over the years but I still dont use a scope much. Maybe making it easier to conmect would help.
Ok, you made me curios so I checked my '71. When I converted to electric fans and EFI I swapped out the stock 10SI alt for a 12SI. It's an el cheapo Autozone rebuild, but it's been fine for years. With fans running half speed + stereo on (big Rockford Fosgate amp from the 90's) I got this:
Alternator stud: 0.18V
Battery: 0.016V (notice the extra zero in there)
Btw, no need for a scope to measure ripple. A good 'True RMS' volt meter is all you need. I use a Brymen BM829s.
Ok, you made me curios so I checked my '71. When I converted to electric fans and EFI I swapped out the stock 10SI alt for a 12SI. It's an el cheapo Autozone rebuild, but it's been fine for years. With fans running half speed + stereo on (big Rockford Fosgate amp from the 90's) I got this:
Alternator stud: 0.18V
Battery: 0.016V (notice the extra zero in there)
Btw, no need for a scope to measure ripple. A good 'True RMS' volt meter is all you need. I use a Brymen BM829s.
Can you measure one more item? The starter post to battery negative.
Totally stock wiring inmy car.
Here is my reading seems like 100hz ripple but I could be wrong.
Pic shows about 10 waves per 100ms division. Last pic shows how ripple stops but baseline voltage remains as soon as I turn off engine.
The thing that seems to potentially invalidate my test os that the scope shows 1.6v not 13-15v as I wouls expect. This could be because my probe has a 10x switch on the side.
Hey buddy. No hurry in this quest.
We just need volunteer #2. Mike>? Do you have access to a scope?
Been watching this thread, but have been tied up with unexpected family stuff the past few weeks. Finally getting caught up. I've got a couple scopes that have been gathering dust lately, but I oughta be able to play around a little on this topic. The '69 is apart right now to take some more weight out of the car, but my "84 is running. I moved the battery in it to the rear compartment for better weight distribution, so it ends up electrically configured somewhat similar to a C3. I run small batteries in both cars for reduced weight, but I can probably scrounge/install a regular size battery too for a bit of comparison purposes.
01-10-2019, 07:21 PM
