Hot Rod Forum banner
1 - 6 of 6 Posts

·
1969 Mustang Coupe Project Car
Joined
·
1,270 Posts
Discussion Starter · #1 ·
Hey all:
I'm upgrading the electrical system in the 69 Mustang with a PA Performance 1G to 3G conversion kit. But what about the stock Group 35 type battery? The new system at peak should produce about 120 amps, can that battery handle that much extra current. I mean I know it will only pull what it needs from the system but will it cause it to have issues with charging to fast and thus to much heat etc.

Thanks
Mark
 

·
Registered
Joined
·
2,804 Posts
I know very little about the 3G alternator, but the charging system is designed to be self regulating, and using the original battery with a high amp alternator should not be a problem. The battery acts as a buffer/storage between the alternator and the power requirements of the car. The alternator will only generate 120 amps if the car needs it to keep up with current load, so most of the time the battery never sees anywhere close to that amperage.

Where I have seen some issues is if the battery gets run down to a low voltage (lights left on, etc.) and then you start the car and the new high amp alternator kicks in to charge it quickly. It puts a real strain on a V-belt system and you might throw or break a belt.

Bruce
 

·
Registered
Joined
·
159 Posts
Not a problem. That battery don't care what the amp capabilities of the alternator are as long as it keeps up with the draw from the cars accessories. The regulator reacts to voltage. It don't matter what causes the low voltage, it will try to get the system up to 12.5V. You could use the G3 to run on a lawn tractor battery with no issues.
 

·
Hates: Liver. Loves: Diesel
Joined
·
6,311 Posts
Agreed. The battery sets its own current rate when charging. Ever notice when you hook up a 15A charger to a battery and it only reads 5A on the gauge? Or when you hook up jumper cables to a vehicle with a 120A alternator, the dead battery doesn't suck up 120A. Nor does it suck up the 900A available from the battery in the jumping vehicle. It takes what it can. Voltage is what determines charging "force."

Just make sure you wire the alternator with big enough copper to handle the new potential.
 

·
Registered
Joined
·
4,263 Posts
You should be looking at CCA. If you can fit a dual post 34/78 battery most of those are 800 with 1000 being available. Compare that to most 34's around 700. Those extra post come in handy for running relays and such.
If you have a high compression or just a big block the extra amps are worth every penny.
 

·
1969 Mustang Coupe Project Car
Joined
·
1,270 Posts
Discussion Starter · #6 ·
I want to thank everyone for the reply's I'm increasing the amperage because I'm adding dual fans and an EFI system. I'm staggering the fan startup due to the 24 amps they will both draw. No big Stereo here so I think this will be more than enough. The extra posts I need to a constant voltage for the EFI etc. I'll have to see what the size difference would be with the 34/78 battery. Again I can't thank you guys enough for the feedback. The Altenator kit arrives tomorrow so that will most likely go in this weekend after I finish with the LED headlight upgrades.
Thanks again
Mark
 
1 - 6 of 6 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top