lt1 alt/charging help!!

[lt1chevelle]

ok so some reason my batts not charging it could be the way i have it wired but im not sure, so if u guys could let me kno how u have your charging system wired that would help a lot im tired of going out tp start the car and it being dead all the time!!!!(there is a draw in the system to but ill look for that after i fix my charging prob)

[TnBlkC230WZ]

ok so some reason my batts not charging it could be the way i have it wired but im not sure, so if u guys could let me kno how u have your charging system wired that would help a lot im tired of going out tp start the car and it being dead all the time!!!!(there is a draw in the system to but ill look for that after i fix my charging prob)

What is the voltage at the back of the altenator and battery with the engine running at about 2000 RPM? Need to check it with a light electrical load and a heavy electrical load. If the Altenator and battery maintain 14+ volts, the charging system is working.

[lt1chevelle]

i dont think it is working because my volt meter in the car only reads 12 and stays there when the car starts it never goes to 13 or 14. thats why i think its not working and it drops a little when i turn on the water pump or head lights



What is the voltage at the back of the altenator and battery with the engine running at about 2000 RPM? Need to check it with a light electrical load and a heavy electrical load. If the Altenator and battery maintain 14+ volts, the charging system is working.

[TnBlkC230WZ]

i dont think it is working because my volt meter in the car only reads 12 and stays there when the car starts it never goes to 13 or 14. thats why i think its not working and it drops a little when i turn on the water pump or head lights

You will not know until you measure voltage at the altenator. The voltmeter only tells you what voltage at the gauge is. There are lots of things that cause voltage drop. If you wired your sense wire to the back of the altenator, I would expect the voltmeter to read less than 13 volts. If your wiring is undersized for the length of the runs, then the gauge will only see 12 volts.

[Samckitt]

While the car is running, remove the positive from the battery post. If it dies, alt not charging, if it continues to run, alt is charging.

[MonzaRacer]

While the car is running, remove the positive from the battery post. If it dies, alt not charging, if it continues to run, alt is charging.

While a lot of people like to do this is till cause damage electrically and it does not allow the system to function properly and it can blow many a very expensive things electronic.
as in NEVER NEVER NEVER NEVER NEVER NEVER DO THIS,,,DID i SAY NEVER, I MEAN NEVER.
If you have a volt meter you need a full 12 volts at back of alt engine off. depending on which alternator you run you really need one wire looped to battery terminal and the other ran from 12 v key on run to either the F or L terminal on CSI alternators and on 10si alts to the R terminal and the S terminal ran to battery terminal on back of alt.
Another good thing to check is simply make a 10 gauge wire and connect from alternator battery terminal to battery positive or closest connection to battery. If the harness has a fuse link or too small of wiring and even crimp terminals not soldered after you may get charging issues.I need to know which alternator you have to be sure on how to wire it up.
Let me know if any of this helps.
Oh and did I say NEVER pull positive battery terminal off while running or even if its off.
Remember this wise old rule. NEgative first off and last back on,,, oh and for the "old hands at jump starting, remember negative to dead battery/car is last on and first off.
if electronics lose ground they act wonky, if they lose poser side they can get damaged.
Ask me how I know this problem?
LONG expensive story, and learned it from my instructors many moons ago.
Lee Abel
AFTERMARKET PERFORMANCE

[John Wright]

While the car is running, remove the positive from the battery post. If it dies, alt not charging, if it continues to run, alt is charging.
I agree with Monza on this....older cars without electronics...you can get away with it....the voltage spike or surges twisting off the cables makes electronics very unhappy.

[lt1chevelle]

its a powermaster alt

[TnBlkC230WZ]

depending on which alternator you run you really need one wire looped to battery terminal and the other ran from 12 v key on run to either the F or L terminal on CSI alternators and on 10si alts to the R terminal and the S terminal ran to battery terminal on back of alt.


If you run the S (sense) wire to the battery terminal on the altenator, you probably will only have 12 volts at your dash mounted gauge.

The exciter wire needs some type resistor or idiot light in line to lower the voltage.

Powermaster makes lots of different altenators. Do you know which one it is?

[lt1chevelle]

ill dig around an see if i can find out what one it is.


If you run the S (sense) wire to the battery terminal on the altenator, you probably will only have 12 volts at your dash mounted gauge.

The exciter wire needs some type resistor or idiot light in line to lower the voltage.

Powermaster makes lots of different altenators. Do you know which one it is?

[TnBlkC230WZ]

ill dig around an see if i can find out what one it is.

Post a pic of the alt and connector. It will be easy to figure out.

[MonzaRacer]

As for the CSI alternator its sensing voltage not turning on the regulator that is what the L wire does through the "idiot" light.
"Idiot" light wiring comes from gauges fuse usually a 20 amp fuse "unless your adding an idiot light then the regualtor only needs about 10 or 15 amps max" then through the "idiot light" then to the L terminal.
As for the sense wire its like on old 10SI/12SI conversions, the S terminal goes to battery positive(basically this is termed the stator wire) and the F terminal gets power from the "idiot" light wire which is still a key on run fused source.
Also some cars will require a 400PIV diode in line in idiot light wire to keep car from continuing to run with key off. I used to get mid to late 70s and early 80s cars that would have charging problems and then would find them also having blower motor issues, turns out GM was "saving wire " by picking this circuit for the fused 12 v key on power to the idiot light, also noted some cars would "blink" battery/alt light when fan was ran, most thought it was bad alt when it was bad wiring.
Oh and for the real truth pulling the positive cable was an old "quick" test for generator systems and on specific system polarized the generator/regulator. And even GM sent multiple bulletins to dealer when alternator came out to not do this as damage would result.

Lee Abel
AFTERMARKET PERFORMANCE

[69camarokid]

the original LT1 voltage gauge has a built in resistor in it. since you are running a non LT1 stock voltage gauge you dont have it. Without this the correct signal will not be sent tell the alternator how much to charge.

I had this issue with the LT1 in my 69 camaro. I used to only dram around 10 Volts til i installed mine. now it draws about 12.5 to 13. I dont remember how many ohms the resistor is though. i want to say like 57 ohms or so. im sure you can find it somewhere though

[lt1chevelle]

where do u have the resistor wired in at?
ill try and get some pics this week! i know on the alt it has the post coming off it thats copper, and i have a wire ran there to the POS side of the batt. and then it has a pug where the harness plugs into. what gauge wire do u recomd running off that post to the batt?

[73X]

I think if you have a direct LT1 replacement, it's a CS144. Unless I'm wrong, it should wire the same as a CS130. Here's a diagram that should help

[lt1chevelle]

thanks but thats hella small i cant read it lol

[camrat68]

CS144 is the correct one. If the accessory bracket has been painted or powdercoated, add a 12ga ground wire to the back side of the lower mounting bolt to the head or a chassis ground. Quite a few people in the LT1 Caprice/Impala world have run into the same problem. I haven't heard about the non-LT1 resistor fix before. I'll have to check into that since I have a friend who is dropping an LT1 into a third gen Camaro. Also don't disconnect the battery + while the car is running or you will fry the PCM.
Jim