Electrical system help

[Blue88Coupe]

I've got a 90 mustang with the stock 75amp altenator. The battery has been moved to the trunk and I have a 10 gauge wire running from the altenator to the battery side of the solenoid. How can I check that the altenator is charging the battery correctly?

I also have a CSR electric water pump and A1000 fuel pump and stock pcm. I am about to hook up an electric fan as well. Will the stock altenator cover all of this or do I need to upgrade and if I do need to upgrade what should I go with?

[greenbullitt]

upgrade to a 94-95 3g. You will need more than a 10ga then. Put a voltmeter on the batt when running, that will tell you what its charging

[dville_gt]

I use a 4 gauge wire from the battery to the alternator and a 2/0 from the battery to the starter. 10 gauge is TINY. (granted my alternator puts out 140amp but still) I'd definitely suggest a new higher output alternator.

[91CoupeMike]

Stock alt won't be able to carry all that load. It barely gets by on stock electronics. The blower motor and lights are too much already.

[Blue88Coupe]

upgrade to a 94-95 3g. You will need more than a 10ga then. Put a voltmeter on the batt when running, that will tell you what its charging

Battery is 12.06 car off and 11.80 car running.

[greenbullitt]

not charging

[Blue88Coupe]

not charging

Can I say the altenator is working its just not putting out enough juice to charge everything?

[Snatch Napkin]

Raise the rpms to 2500 and see what it does for the voltage.

[Blue88Coupe]

I put the 3g on there. I've got 11.70 across the terminals idling around 800-900 rpm. Im bouncing between 12.30 and 11.70 if I ground to the head and come off the lug on the back of the alternator.

I'll try and upgrade the cable going from the alternator to the solenoid post from 10 gauge to 4 gauge tomorrow and see if that helps

[dville_gt]

I put the 3g on there. I've got 11.70 across the terminals idling around 800-900 rpm. Im bouncing between 12.30 and 11.70 if I ground to the head and come off the lug on the back of the alternator.

I'll try and upgrade the cable going from the alternator to the solenoid post from 10 gauge to 4 gauge tomorrow and see if that helps

Are you running a kill switch? If so you'll want to run the 4 gauge straight back to the battery otherwise when you flip the kill switch you will very likely fry your alternator. Some people worry about having the alternator going straight to the battery and bypassing the kill switch thinking that this would allow the motor to continue to run after the switch has been turned off. This would not be the case on an efi car w/an electric pump since all the engine controls and fuel would be off.

[Blue88Coupe]

Are you running a kill switch? If so you'll want to run the 4 gauge straight back to the battery otherwise when you flip the kill switch you will very likely fry your alternator. Some people worry about having the alternator going straight to the battery and bypassing the kill switch thinking that this would allow the motor to continue to run after the switch has been turned off. This would not be the case on an efi car w/an electric pump since all the engine controls and fuel would be off.

I'm not running a kill switch. This thing is anti tech friendly.

[Blue88Coupe]

I put the 3g on there. I've got 11.70 across the terminals idling around 800-900 rpm. Im bouncing between 12.30 and 11.70 if I ground to the head and come off the lug on the back of the alternator.

I'll try and upgrade the cable going from the alternator to the solenoid post from 10 gauge to 4 gauge tomorrow and see if that helps

I've got a four gauge cable coming from the back of the altenator to the side of the solenoid that connects to the battery.

I just had the altenator checked and they said it was good.

I'm still only getting 11.45 across the battery terminals with the car running.

Whats next?

[91GriggsGT]

Raise the rpms to 2500 and see what it does for the voltage.

^^^^^ This. The 3G alternators will not kick in and start charging until you put some RPMs to it.

Also, are you sure you have the charging wire hooked up?

[Blue88Coupe]

^^^^^ This. The 3G alternators will not kick in and start charging until you put some RPMs to it.

Also, are you sure you have the charging wire hooked up?

the charging wire is the 4 gauge? if so im positive its hooked up.

[91GriggsGT]

I believe you should have that 4ga, and a smaller, maybe 12ga wire connected to the same stud on the back of the alternator.