Alternator performance questions.
Thread Starter
Le Mans Master
Joined: Aug 2017
Posts: 6,941
Likes: 1,490
From: New Jersey
Being the case was marked and I did disassemble it they may give me a hard time about it... especially since looking back through my print outs I went through 3 before one had a reasonable A/C ripple and I had to fight for it... they may not like me sending back another one. I however have still reached out and maybe they'll pull through. So I will update. Otherwise it's getting a rebuild with good parts and I'm calling it a day. I've never had issues with parts like this when I'm the one fixing them so we'll see. Probably what will happen.
Team Owner
Joined: Sep 2003
Posts: 25,393
Likes: 2,741
Being the case was marked and I did disassemble it they may give me a hard time about it... especially since looking back through my print outs I went through 3 before one had a reasonable A/C ripple and I had to fight for it... they may not like me sending back another one. I however have still reached out and maybe they'll pull through. So I will update. Otherwise it's getting a rebuild with good parts and I'm calling it a day. I've never had issues with parts like this when I'm the one fixing them so we'll see. Probably what will happen.
My CS144 broke a wire on the dyno at 7000RPM. Seems the armature is made of two halves and the fan belt sprocket side can move before the back half does when I punch it, just a little, and under quick acceleration it broke a wire that connects it to windings inside. So there's another downside to it.
Had to repair mine, guess I am going to have to go with some kind of racing alternator or something if I plan any trips to the track next year, or chassis dyno time when I put the new headers on
Last edited by WVZR-1; May 5, 2021 at 12:12 PM.
Thread Starter
Le Mans Master
Joined: Aug 2017
Posts: 6,941
Likes: 1,490
From: New Jersey
When you're shopping for a new rotor/armature you might ask about it's fabrication/construction. Some/a majority of CS144 rotors are 2-piece fabrications and a failure similar to yours at higher RPM is a 'to be expected'. I've only seen it mentioned 1 time here and a very long time ago. Here's that post.
It seems there is only one manufacturer left for the rotors anyway... J&N. The one I found was reasonably priced and they had a full setup with stator laying around too for a HO unit... I'll pull the trigger on it depending on what they get back to me with. Seems like a quality piece so who knows. The wire when it came apart impacted the stator in mine. It ohms out fine but its enough damage that I would rather not deal with it... If it is a full rebuild I can rest easy rather than dealing with another three "maybe they're good" delco units. The time and hassle vs price is worth it to me. I simply don't have the time to keep screwing around with the car with my current work schedule. I just want to get in and not worry about it. Still going to see what ACD gets back with though. If they exchange it then I am golden imo.
Thread Starter
Le Mans Master
Joined: Aug 2017
Posts: 6,941
Likes: 1,490
From: New Jersey
I'd classify that failure as a "crappy part". The wire broke at the brush connection, got flung outwards into the stator, and broke-up / ground off. That wire doesn't have much mass and is close to the center line of rotation. There isn't much stress placed on it by centrifugal force. My guess is that the wire was nicked during the enamel-removal prior to soldering, and this stress riser resulted in the wire parting during the high RPM event.
I feel you're doing the right thing by slowing down the alternator using a lower drive ratio. I'd try to find a 3" alternator pulley and call it done. This will give you a 2.4 ratio which is 1,700 alternator RPM at idle and 14,400 at 6,000 engine. That might be a little slow at idle depending on your electrical loads. Consult an alternator performance graph and compare output at the lower speeds to your load. Coolant fans, fuel pump, and blower motor are the biggies. Incandescent headlights also add considerable load when on, and need to be included if you do much low-speed driving with headlights.
Final suggestion: The CS144 uses a PLI/FS regulator. Utilize the "S" terminal. Connect this terminal directly to your battery (+) post or the junction block that the other loads are connected to. This connection will cause the regulator to "Sense" and regulate the output to overcome any voltage-drop in the output wiring so that the desired voltage is present at the sense point. Ie, If the voltage-drop is 1.0 Volt and the set-point is 14.2 Volt, the voltage at the alternator output terminal will be 15.2V, but the voltage at the "Sense point" will be the desired 14.2V. Utilizing the S terminal can greatly increase charging performance which results in more rapid battery recovery when the engine RPM comes up from low-speed alternator output that may be marginal to cover the loads.
I'll leave this one up.
I feel you're doing the right thing by slowing down the alternator using a lower drive ratio. I'd try to find a 3" alternator pulley and call it done. This will give you a 2.4 ratio which is 1,700 alternator RPM at idle and 14,400 at 6,000 engine. That might be a little slow at idle depending on your electrical loads. Consult an alternator performance graph and compare output at the lower speeds to your load. Coolant fans, fuel pump, and blower motor are the biggies. Incandescent headlights also add considerable load when on, and need to be included if you do much low-speed driving with headlights.
Final suggestion: The CS144 uses a PLI/FS regulator. Utilize the "S" terminal. Connect this terminal directly to your battery (+) post or the junction block that the other loads are connected to. This connection will cause the regulator to "Sense" and regulate the output to overcome any voltage-drop in the output wiring so that the desired voltage is present at the sense point. Ie, If the voltage-drop is 1.0 Volt and the set-point is 14.2 Volt, the voltage at the alternator output terminal will be 15.2V, but the voltage at the "Sense point" will be the desired 14.2V. Utilizing the S terminal can greatly increase charging performance which results in more rapid battery recovery when the engine RPM comes up from low-speed alternator output that may be marginal to cover the loads.
I'll leave this one up.
The underdrive set I ordered takes the crank to alternator pulley ratio to approximately 2.1. (5-5/8 crank and 2-3/4 alt. Pulley) If I were to retain the stock diameter pulley on the cs144 it is about 2.38. (5-5/8 crank and 2.4 inch pulley). The underdrive is the way to go in my opinion...
As far as output, I've simply found one of the "stock" generic curves and so long as that's reasonably accurate, I should still have give or take 80 amps on tap at the ~1700 rpm shaft speed you've described. That should be adequate. Worst case it still runs the battery down a little sitting in traffic in the rain in the summer with the AC cranked. It's a tradeoff that's going to have to be made for longevity of the parts.
The 3 inch alternator pulley I had located comes to about 1/3 the price of the whole underdrive setup... my crank pulley had a small dent in it anyway, so it seems like I'm better of just doing the whole thing. I am unsure how that occurred as it was fine when I reassembled everything last year. I wonder if I damaged it wrestling with the rack and pinion.
I'll have to double check how the "adapter" is wired. It utilizes the factory 2 wire plug and just jumps out to the CS plug on the alternator side. So I believe it uses the S terminal. I'm just unsure where it is attached. I'll refer to the wiring supplement for 84 to confirm where exactly it is located and simply disconnect and reroute it to the distribution block where I have the load for the fans.
Thank you again.
