Diagnosing charging system health '70 Barracuda EFI

[Mopsquad]

I'm not far from you over in Indio.

I build the 6 and 8ga charge wires with a fusible link.  Try to make them stealthy as well.   Simple to install.  I may have an ad up here somewhere.

Where are you tapping the system for your EFI?    Battery or starter relay on our mopars is a horrible spot with the factory charging system.

Let me know if I can help.

Thank you. I will certainly contact and inquire.

The EFI and MSD battery source are tapped at the junction pictured.

[Mopsquad]

The large stud on the Alt  with the 1/2" nut & the start relay , 1 wire from the positive battery terminal bolts to the relay

Is this the stud on the alternator that I tap into? Black plastic cover

See pic

[crackedback]

That's the starter relay. 

[Mopsquad]

That's the starter relay.

I used it as a junction block to limit the amount of wires direct to battery pole.

[YellowThumper]

The large stud on the Alt  with the 1/2" nut & the start relay , 1 wire from the positive battery terminal bolts to the relay

Is this the stud on the alternator that I tap into? Black plastic cover

See pic

Yes that is correct alt stud. Notice how small the factory wire is... now picture that and only a blade terminal thru bulkhead.

[Mopsquad]

The large stud on the Alt  with the 1/2" nut & the start relay , 1 wire from the positive battery terminal bolts to the relay

Is this the stud on the alternator that I tap into? Black plastic cover

See pic

Yes that is correct alt stud. Notice how small the factory wire is... now picture that and only a blade terminal thru bulkhead.

Thx. So I'll directly connect a 8ga wire from that pole to the battery.

[crackedback]

That wire MUST have circuit protection of some kind.

Yeah, people use the starter relay as a bus point and it's a horrible place to do it on our cars without the wire around set up.

[73440]

fusible link will work good for that.

[Mopsquad]

That wire MUST have circuit protection of some kind.

Yeah, people use the starter relay as a bus point and it's a horrible place to do it on our cars without the wire around set up.

I can use a separate junction pole outboard of the relay and use a 8 ga or so to connect to battery.

What amp fuseable link?

[RCman]

I'm also going with the stock alternator doesn't have enough gusto to keep up with the EFI / electronic ignition demands.
I ran into this exact same issue. I ended up grabbing some brackets from AR Engineering from Mancini Racing (Brad's post linked it) so I can run a Denso alternator for a 4cyl 2.4L 4Runner from 85-92 which has the same style v-belt pulley. 93-95 will also have a v-belt pulley but is a different plug end. Mancini has the plug and wiring for the 85-92 style. I now have no problem with 14.1+ V at idle. It is a slick setup and super easy to do, especially if you've already run the wire from the alt to the starter relay/battery (with protection of course).

[Mopsquad]

I'm also going with the stock alternator doesn't have enough gusto to keep up with the EFI / electronic ignition demands.
I ran into this exact same issue. I ended up grabbing some brackets from AR Engineering from Mancini Racing (Brad's post linked it) so I can run a Denso alternator for a 4cyl 2.4L 4Runner from 85-92 which has the same style v-belt pulley. 93-95 will also have a v-belt pulley but is a different plug end. Mancini has the plug and wiring for the 85-92 style. I now have no problem with 14.1+ V at idle. It is a slick setup and super easy to do, especially if you've already run the wire from the alt to the starter relay/battery (with protection of course).

.

Thx for the suggestion. I'm going to test the alt first.

[1 Wild R/T]

My stock frame round back style alternator with upgraded diodes will push 85 amps so I see no need to put a Japanese alternator on my car....  I know the Denso's work great & I'm not saying thee's anything wrong with doing the change, I just prefer to keep my car "looking" stock...

[73440]

Example,
10 Ga. wire, 14 Ga. fusible link.
8 Ga. wire, 12 Ga. fusible link.

[Chryco Psycho]

You have already proven there is more load than the alt can handle at idle so if you get caught in traffic you can run the battery dead & fairly quickly too as you have proven  , so My belief is you need to upgrade the alternator output to keep up with the load wether you modify the stock alt as Wild suggests or change to a high output one you will have to do it  , I have run into this a few times now with modern upgrades !
  You absolutely still need the bypass especially if the alt can produce more than 60 amps as the ammeter gauge cannot handle more than 60 amps & the connections through the bulkhead do not like 60 amps either .

[Mopsquad]

You have already proven there is more load than the alt can handle at idle so if you get caught in traffic you can run the battery dead & fairly quickly too as you have proven  , so My belief is you need to upgrade the alternator output to keep up with the load wether you modify the stock alt as Wild suggests or change to a high output one you will have to do it  , I have run into this a few times now with modern upgrades !
  You absolutely still need the bypass especially if the alt can produce more than 60 amps as the ammeter gauge cannot handle more than 60 amps & the connections through the bulkhead do not like 60 amps either .

I can see a new alternator in my future. I'm curious about this bypass test with 8ga wire. Can I just temporarily connect the 8ga wire from alt stud to battery to test voltage?  I had to read up on what a fuseable link was - didn't know. For this test, can I not use a link?