 
     |
| I can NOT figure out why my battery wont read over 12v when on (3800 swap) (Page 3/4) |
|
Threedog
|
AUG 09, 09:26 PM
|
|
| quote | Originally posted by theogre:
⚠️ The battery is "Dead" and why see 11 or less when alt is off etc. Charge the battery. Low/Dead Battery alone can make any CS to stay off. ECM controlled or not. Is done so the Alt won't fry trying to charging a dead battery.
|
|
Between these three batteries. I have tried when they are new, when they have been on a trickle charger for days, from when they came off another car (charging), and jumping it with a power pack. In all of these cases, the results are the same. 10.5-11 volts when running without alt plugged in and 11.9-12.1 volts with it plugged in.
I have a new belt and new alt coming this weekend and I am going to try those. If they don't work ill rewire it, if that doesnt work ill send my 96 PCM off to get programmed to 1997 (same number of pins and connectors, but there are differences).
The only alternative I can think of is..how would I wire this to bipass the ECM?[This message has been edited by Threedog (edited 08-09-2022).]
|
|
|
|
Threedog
|
AUG 16, 12:01 PM
|
|
Bump
Anyone know how to completely bypass the ECM in terms of alternator voltage?
|
|
|
theogre
|
AUG 16, 12:59 PM
|
|
You can't w/ that alt. In very short... The "Digital" regulator can use different types of "signal" from the ECM to run or never turns On or defaults to X volts if turns On. Later seems to be what is happening.
Example: ECM sends Pulse Width Modulation "signal" on 1 line to set the alt's Volts Out from main alt out. No signal = default output volt. Would need carefully setup an Arduino etc to emulate this and done wrong can wreck ECM Radio etc for High Volts from the alt very easy.
Likely Need a "dumb" CS130 or CS130D and wired as F type in cave unless you know for sure can wire as I type.
D has no external fan and bit smaller then CS130.[This message has been edited by theogre (edited 08-16-2022).]
|
|
|
|
sanderson231
|
AUG 16, 11:04 PM
|
|
|
Everything points to the PCM. You have a spare. ------------------
formerly known as sanderson
1984 Quad 4
1886 SE 2.8L
1988 4.9L Cadillac
1988 3800 Supercharged
|
|
|
|
Threedog
|
AUG 17, 04:46 PM
|
|
| quote | Originally posted by theogre:
You can't w/ that alt. In very short... The "Digital" regulator can use different types of "signal" from the ECM to run or never turns On or defaults to X volts if turns On. Later seems to be what is happening.
Example: ECM sends Pulse Width Modulation "signal" on 1 line to set the alt's Volts Out from main alt out. No signal = default output volt. Would need carefully setup an Arduino etc to emulate this and done wrong can wreck ECM Radio etc for High Volts from the alt very easy.
Likely Need a "dumb" CS130 or CS130D and wired as F type in cave unless you know for sure can wire as I type.
D has no external fan and bit smaller then CS130.
|
|
Ogre, I should have known better than to question your knowledge, it was the battery.
Turns out that Optima Batteries are "AGM" batteries, of which I was not aware. When I got a new alternator, before I started it I switched my trickle charger to "AGM" mode and let it charge overnight.
Turns out my trickle charger was never properly charging the battery because it was in the wrong mode (probably what led to my alternators dying repeatedly). Now that it is charged up, when running the car I have a perfect 13.8-14v. Thanks all!
|
|
|
Patrick
|
AUG 17, 05:03 PM
|
|
| quote | Originally posted by Threedog:
...it was the battery.
Now that it is charged up, when running the car I have a perfect 13.8-14v.
|
|
I'm missing something here.  Was the Jetta battery not charged up either?
| quote | Originally posted by Threedog:
Swapped the battery with my jetta as well and it continues to read at 12.1 on, 11.9 off.
|
|
|
|
|
|
Threedog
|
AUG 17, 05:50 PM
|
|
| quote | Originally posted by Patrick:
I'm missing something here. Was the Jetta battery not charged up either?
[QUOTE]Originally posted by Threedog:
Swapped the battery with my jetta as well and it continues to read at 12.1 on, 11.9 off.
|
|
[/QUOTE]
That was with the old alternator, which wouldnt go above 12.1 volts no matter what. I think I ruined that one.
It only worked with a new alternator and a charged up battery. All that being said it could have just been the alternator, but considering I had already swapped that multiple times I think it was a combination of both. Maybe it was just that O Reilly alternators are **** ? The three I used were all "warranty returns" for new rebuilt units. The newest one (that worked) I got off of rockauto[This message has been edited by Threedog (edited 08-17-2022).]
|
|
|
|
theogre
|
AUG 17, 06:10 PM
|
|
Guess the Jetta was low too then put in Fiero made it lower still....
Starting w/ CS types.... GM setup the regulator to Not to Turn On w/ a "dead" battery. CS I've read is battery "dead" when ~ 11.5 volts.
Why? The SI and others didn't and battery too low draws a lot of Amps and kills the alt.
Many ADxxx series alts etc may look likes whatever CSxxx but wired w/ ECM/PCM control.
Even if battery is say 12.2 to 11.9 volts... so "should be" above cut off volts right? Sadly Don't count on that. If you scan ECM/PCM battery volts you find that value is not same and little to a lot lower vs Meter on the battery because of iffy wiring. But even best wiring have fractional volt drop to ECM.
Even the OBM 1 ECM for Fiero you see same thing but the ECM doesn't control the SI12 or CS130. Car has a lot of switches, joints and connectors in power and ground for the ECM and even point you get another V-drop. IOW is same thing covered electric motor page when just 1 iffy wire or joint can fry the motor and/or anything controlling them like keep frying relays.
Again CS130 can self protect but have less wiring and often bigger wires too so even if both systems have same cut off volts, less likely to have a low battery shutting down charging.
|
|
|
|
Threedog
|
AUG 17, 06:49 PM
|
|
| quote | Originally posted by theogre:
Guess the Jetta was low too then put in Fiero made it lower still....
Starting w/ CS types.... GM setup the regulator to Not to Turn On w/ a "dead" battery. CS I've read is battery "dead" when ~ 11.5 volts.
Why? The SI and others didn't and battery too low draws a lot of Amps and kills the alt.
Many ADxxx series alts etc may look likes whatever CSxxx but wired w/ ECM/PCM control.
Even if battery is say 12.2 to 11.9 volts... so "should be" above cut off volts right? Sadly Don't count on that. If you scan ECM/PCM battery volts you find that value is not same and little to a lot lower vs Meter on the battery because of iffy wiring. But even best wiring have fractional volt drop to ECM.
Even the OBM 1 ECM for Fiero you see same thing but the ECM doesn't control the SI12 or CS130. Car has a lot of switches, joints and connectors in power and ground for the ECM and even point you get another V-drop. IOW is same thing covered electric motor page when just 1 iffy wire or joint can fry the motor and/or anything controlling them like keep frying relays.
Again CS130 can self protect but have less wiring and often bigger wires too so even if both systems have same cut off volts, less likely to have a low battery shutting down charging. |
|
\
Is it possible I ruined the internals of the other alternator(s)? With the new one, when it was unplugged it read at 11.9-12v, and when I shut it down and plugged it in it went to the correct high 13/14. With any of the other alternators, it was 12v plugged in and either 10v or sometimes still 12v when uplugged.
Edit: Just tried the older alternator to see if it works, won't hit above 12.1 under the exact same circumstances as the new one. I must have screwed up something on the inside.[This message has been edited by Threedog (edited 08-17-2022).]
|
|
|
|
theogre
|
AUG 18, 12:15 PM
|
|
| quote | Originally posted by Threedog:
Is it possible I ruined the internals of the other alternator(s)? With the new one, when it was unplugged it read at 11.9-12v, and when I shut it down and plugged it in it went to the correct high 13/14. With any of the other alternators, it was 12v plugged in and either 10v or sometimes still 12v when uplugged.
Edit: Just tried the older alternator to see if it works, won't hit above 12.1 under the exact same circumstances as the new one. I must have screwed up something on the inside. |
|
Maybe.
Try taking to local auto parts store...
But...
If really is ECM controlled... Would need a "Bench Test" machine that can test this type that can emulate ECM/PCM controlled for the reg's. Most shops know what type by looking at it or even can tell by yr, make, model of car came w/ the machine maybe can't test this. Many parts stores have very old alternator test machines.
|
|
|
|