Crumpler

Just installed the 928 Motorsports 150 AMP alternator.
I won't say it was a seamless, bolt on installation for the 32V engine (had to tap a larger hole on the housing of the new alternator to place bolt for tensioner), but results seem to live up to the billing.







Unfortunately, my good digital multimeter is down, so I had to use the old analog mutimeter tonight.
I get 12V off the jump post when not running and close to 14V when running at idle.

On the voltage gauge in the cockpit I also got 14V, and steady at idle.
All electronics working well (windows indeed, seem less sluggish, maybe wishful thinking). Electric fans kick on without dimming lights, etc.)

My problem started as I pulled out (night drive, so light are on). As I hit brakes the volt gauge dumps down and sets off low voltage warning light. Needle picks back up but warning stays on the whole drive.

The car performs well (normal), but volt needle will consistently sweep up and down when headlights and stop lamps engaged (when I'm on the clutch and brake pedal).

I got home and had my wife in the car while I got readings off the post again.
As she pumped the brakes and got the volt needle to bottom on the cluster, I did not have those fluctuations at the post.

I have always had a gremlin in the cluster, in that the oil pressure stays pegged until car is driven long periods and car idles with clutch in -- then spot on.

So I guess I was hoping you guys could give me a sanity check... this is a short somewhere between the gauge and the 14 pin connector right? And with a better alternator, it's more pronounced?
Or do I need to worry about new alternator's function???

I also can't seem to get the low voltage light off on the gauge, even un-hooked the battery.

Thoughts appreciated.

GregBBRD

It's tough to find an oil pan without the ribs scraped from hitting the ground.

From your picture, it appears that the positive post sits an inch below the oil pan.

Hopefully this is an optical prespective issue caused by how the picture was taken and the alternator really isn't the lowest thing on the car?

'Cause that would be really........not well engineered.

Crumpler

So that's not as bad as it looks there, thankfully.
That post is for an extra ground wire and it sits proud of the alternator, but not further then the pan. I have chin protectors on, and a dust pan (rare for sure).

What became cumbersome was that the alternator pulley size is bigger then stock by 15 mm. I checked and this is by design apparently. But that required loading the belt on the crank and alternator pulley first and then hanging the alternator.

I was going to go get a new multimeter today and get better readings.
My bigger concern is not the low voltage readings, it's the possibility of high...and what's too much?

I guess I'm in a small demographic, in that I am willing to take on these projects without the skill in circuits to save myself.

Alan

The extra case ground seems to be in an unfortunate location - seems an upper location into the case ought to be possible. However, if the readings at the jump post are OK then the alternator is working OK.

>~14V is OK at initial - but it should not be sustained throughout running - it will overcharge the battery - if it drops off over time to to ~13.8V (as the alternator warms up) then that is OK.

Seems you have pod connections issues - not likely a short, probably more like poor (degraded/loose) connections. I'd suggest:

1) Clean the grounds - especially behind the CE panel and behind the pod.

2) Check all voltages at the CE panel - esp. with ignition on & and modulating headlights/brakes: test Battery (30) ignition (15) and accessory (X). This will help you figure out if the issue is at the CE panel or at the pod.

3) If indicated by 2) - Remove the pod and evaluate & clean all the pod connectors.

Alan

ltoolio

Since when does "Plug and Play" include tapping a larger hole?

Speedtoys

That's the play part.

Remember to select a safeword first..

skpyle

"Bosch"


Seth K. Pyle
No ball gag needed.

Crumpler

I hear what you guys are saying, loud and clear.
Alan, thanks for following, very glad you are here.

Ok so with a multimeter:

Pre-start volts on post (a little low) 12.02

Start up: 14.48V on post ----- 14V on gauge

1min running: 14.39 post ----14 gauge
2min 14.39v-----------14
3min 14.37v-----------14
5min 14.35v-----------14
cooling fan kicks on and volts drop to 14.21v, gauge shows 13.9 and red light appears on voltage warning. Cooling fan kicks on when coolant 180 degrees.

hitting brake lamps shows 1-2V decrease blip on gauge, but only .07 decrease on multimeter.

At 9 min: 13.96V on the post and 13.6 (ish) on gauge.
but, when fan cycles off, mutimeter goes up to 14.10 volts.

Fan, headlights, and radio shows 13.81 volts on multimeter.

Engine off and resting voltage on post is 12.39V.

I guess I'm more at ease calling the erratic voltage needle movements a problem limited to the pod...but less at ease if the majority of these readings are over 14 volts as Alan said. So I'm getting close to bailing out and putting old unit on....
Also, these are off post -- assume a little higher at battery right?
I don't think my fan runs much on the highway, and that seems to be the only thing getting volts down below 14.0.

All readings are at idle, different at higher RPM's?
Feedback? and thanks ahead of time.
Regards.

Alan

No it will likely be a little lower at the battery - the battery is being charged - so it is a load - the alternator is the source - but it won't be much lower because has a very beefy connection between the alternator and the battery.

5 mins (certainly not idling) is insufficient to fully warm-up. Go drive it for a good 15 minutes then see what you get. Ignore the gauge and use the DMM.

Tell us what you have at hot idle and at hot 2K RPM.

Alan

dr bob

Dave--

Telltale (to me anyway) is the alternator light coming on when volts are fine. Indicates (to me anyway) that the connections between the alternator and the pod is poor. This is backed up by the low dash voltage gauge reading. Were it mine, I'd grab my extended test leads with the allicator clips, and measure the voltage drop between the jump post and the 30 bus (battery voltage) rail on the CE panel where the wires from the jump post connect. Your DMM in 2 volt or 2000 millivolt range will directly indicate voltage drop through those little conductors.

We add high-current-capable alternators like the one you have, then take our time upgrading the wiring between the alternator and the CE panel, and the alternator and the battery cable connection at the starter. I'm in the group that says do the wiring upgrade first. None of that wiring has fuse or fusible-link protection, and virtually all of it is tired and corroded inside to some extent. Stuff to think about.

Crumpler

Ok, thanks Alan, I will do that. That's a little better news then I had anticipated.
I will also run down values at CE as described above (with ignition on and working headlights and tail lamps). Along with 30, 15, and X.

Brief history on the car, I had pulled pod and done R/R several years ago -- I was pleased at the time because I got actual fuel level readings afterward, that I had never had before. Oil pressure has always been off (except when run hot) and I believe the volt indicator has always had a small amount of flutter to it. So the pre-existing issues make sense in hindsight.
CE was also cleaned and got Deoxit several years ago, along with grounds -- but maybe I need to re-visit.
I will get some data and report back in, appreciate it.

Bob, thanks for the insight, I appreciate the help.
I will measure that voltage drop.
Ironic, I was fabricating long wires with alligator clips when you posted -- I'm learning...just, really slowly it seems.

And, yes, good points. I don't know why I just assumed I could drop this in a 30 year old system -- care free and hit the road. Sounds a little naive in hindsight.
I'm not opposed to replacing wiring at this point, I'd like to keep her around for a long time.



I will put some time in and post the findings
Thanks you guys, I'm grateful for the help.
Regards

Alan

You'd want this to be more like 12.6-12.7 seems your battery is a little weak.

Might be worth having it load tested at a good auto store - on a big load tester - not on handheld unit. It could be you have a battery issue that contributes partially - e.g. for the voltage issues - certainly not for the pod behaviour here.

Another thing to check.

Alan

Crumpler

Got it, ironically I was telling a newer member a few days ago how important it was to ensure you had a healthy battery...crazy week, I will check it out!

Crumpler

I had a limited amount of time to get out and tinker today, but I pulled my battery and took it down to the big machine at the parts store for load testing. It did pass all diagnostics.

Hooked back up in the car, I got readings 12.16V at battery and 12.13 at he post, with doors shut (and interior lights off) 12.23 at the post.

I fabbed some test leads from the battery terminals to my mutimeter in the cabin so I could see solid readings on the move in the car.

Start up was 14.46V.
The readings worked down gradually.
At 20 min. I had readings between 13.53V and 13.83V at idle.
At 20 min. I had readings between 13.87V and 13.91V at 2000 rpm.


Granted the voltage gauge on the cluster has not proved accurate, but I would say that the needle is hanging around a comparable spot (when hot) where it did with the old alternator.

I'm feeling a little better overall, but I will continue to get the other readings mentioned prior.
Remaining optimistic and Regards.

Carl Fausett

I also would like you to have your battery checked. In fact, some alternator warranties are void unless you install a new battery with the new alternator - this is so important. A sulfated wet-cell battery can put up so much resistance to the alternator that it thinks the battery is fully charged when it is not. If in doubt, replace the battery.

Did I read correctly that when you put the wife in the car while you checked voltage at the battery post that when she turned on headlights and hit the brakes the voltage did not drop at the post, but the dash "low-voltage" light came on?