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I have a Craftsman 82369 iirc DC clamp meter, which may have peak hold, but I'm not sure, it does work fine for normal steady state stuff and cost me around $30 shipped on ebay, $20 or so more at Sears. A lot of people don't really know how to work a meter, so many that have no real issues get returned and end up on ebay. Iirc high range is 400 amps, works well down to a bit below 10ma, shows I think 1 ma, but I would not trust it, too sensitive to position and movement during DC clamp readings with the car running.
I was able to run the 'S' line from the alternator to the battery this weekend. As suggested, I used a 16G wire since it carries no load to/from the battery. It appears the 'S' wire coming from the alternator was 12G, but I don't think running a 16G will be an issue. I covered the entire wire with a protective sheathing I purchased and in the engine compartment I covered the wire in heat resistance wire covering. You can see the silver foil covered wire loom in the picture below.
In the picture below and circled in red is the 'S' line from the alternator to the battery. I used a smal rubber grommet to protect the wire after I drilled the hole.
I then installed the smaller 52mm pulley on the alternator. Although it may be hard to see, the red marks I previously made showed the alternator was not hitting the power steering pump and I was able to use the same new alternator belt.
So what I have found is the alternator works well when you first start the car, but once the car reaches operating temperature the idle drops below 700rpm and the voltage begins to drop on the alternator. To be fair I have only used the in car gauge to make this assessment and will use a voltmeter on the battery tomorrow to provide actual data.
I was able to adjust the screw shown in the picture below to raise the idle to ~800rpm, which seems to resolve the idle issue. However, after adjusting yesterday and coming back today the car again idles below 700rpm.
I think the next task will be to determine the actual alternator rpm based on the diameter of the crank pulley. If anyone knows the diameter for a 1983 alternator crank pulley let me know so I can do the rpm calculations at the alternator based on the 52mm pulley.
As a note, I tried to measure the pulley diameter by wrapping a piece of material around the pulley to get an estimate on circumference. Based on that crude measurement I calculated the 52mm pulley gave me a 2.5 pulley ratio, which is not that high. Based on what I have read the standard for some OEM CS144 applications is a 2.8 pulley ratio so going to a 48mm pulley may put it in the normal operating range. If anyone can get an accurate pulley measurement we can put this small pulley debate to rest.
Is the S line the exciter wire? Why did you run it to the battery?
You still have the B+ (charging wire) run to the starter, right?
My Delco CS130 charges great when cold (just under 14V on the gauge), but goes down to 12V (per gauge) when hot. Under 12V on the gauge when really loaded.
For your CS144, if you rev the engine up to 1,000 rpm or so, do the volts come up? If not, a smaller pulley will not help.
As a note, I tried to measure the pulley diameter by wrapping a piece of material around the pulley to get an estimate on circumference. Based on that crude measurement I calculated the 52mm pulley gave me a 2.5 pulley ratio, which is not that high. Based on what I have read the standard for some OEM CS144 applications is a 2.8 pulley ratio so going to a 48mm pulley may put it in the normal operating range. If anyone can get an accurate pulley measurement we can put this small pulley debate to rest.
As you work through the pulley ratios, consider that the choice is always a compromise between idle charge current available, vs. high-RPM survivability of the alternator. I have no idea what the max allowable RPM's might be on the alternator, but that would be something I'd want to know as ratios are changed and alternator speed is increased.
Smaller pulleys also reduce the total belt contact area at the same time you are asking the belt to do more work. Watch your belt to see symptoms of slippage especially as the belt ages. The faces of the ribs will look polished at first, and will burn, harden and crack if left slipping too long.
Is the S line the exciter wire? Why did you run it to the battery?
You still have the B+ (charging wire) run to the starter, right?
My Delco CS130 charges great when cold (just under 14V on the gauge), but goes down to 12V (per gauge) when hot. Under 12V on the gauge when really loaded.
For your CS144, if you rev the engine up to 1,000 rpm or so, do the volts come up? If not, a smaller pulley will not help.
'S' is called the Battery Sense Wire and is supposed to run to the B+ terminal of the battery. The B+ on the alternator is hooked to the original factory connector, which I believe one of the wires runs to the starter.
Regarding the rpm, if I rev it up to 1000rpm it is great and from what I can tell it seems to only need about ~800-825rpm to keep full voltage at idle with everything running.
I am going to try and clean all the grounding points. I also see that some accessories create a bigger drain than others with the blinkers and fan motor being the worst offenders. I am going to clean the fuse and relay contacts and repeat the tests.
Whats important with a "sense" wire is that no current is running through it creating a voltage drop that alters the sensed battery voltage. 928 already has such a circuit doesn't it via the charge light in the pod?
Whats important with a "sense" wire is that no current is running through it creating a voltage drop that alters the sensed battery voltage. 928 already has such a circuit doesn't it via the charge light in the pod?
No this is nothing like what we have with the exciter circuit - that has a dual purpose of field initiation (as a current source) and as indicator of alternator charging status.
It really has nothing to do with voltage sensing - which is hardwired to the direct main B+ output inside the alternator for our simple alternators.
GM alternators have more regulator connections with up to 4 control lines Vs our single D+.
P - Phase - A phase output (normally not used)
L - Lamp - dedicated charge lamp driver (can be used for excitation - with limitations)
F - Field - (usually connected to ignition source) provides additional field power for startup excitation
S - Sense - monitor battery voltage remotely
Sense is designed to ensure the battery voltage is correct for charging even when highly resistive main connections are used. GM seems to do this deliberately in some cases and compensates with remote sensing. Compared with most GM cars our battery is quite remote but is connected with a far beefier conductor.
01-23-2015, 05:23 AM
