How stable is the battery voltage? I'm trying to decide which alternator to use in my engine swap.


Anyone have technical information on what signals are what on the stock alternator? I know it's computer controlled but that's about it.

 

I run 2... one plugged into teh cig lighter, and a OBD2 Bluetooth scanner with the "Torque" ECU monitoring app on my phone.

ECU voltage will remain mostly at 13.1 on the OBD2 port, but may dip to 11.9 briefly when the car is very cold and you start multiple accessories.

I read between 11.9 to 14.2 on the cig lighter. again, slightly above the 12v standard for the most part, but most stable between 3-7Krpms (as long as the TCS is not triggered, having the car self activate the TCS cause you are slipping on snow draws a lot of current momentarily and causes the voltage to drop)

 

Seems it varies quite a bit. It becomes an issue for me using large injectors at very low duration. Hard to get a stable idle a/f if the voltage is all over the place.

Thanks for letting me know.

 

Can i ask what injectors your running in p1 and why would you have really big ones in there? Theres really no need and a lot of problems from anything bigger then stock yellows.

Also what year and engine/trans do you have?

 

Crap i just reread it. Your asking for a swap nevermind.

 

i'd reconsider your ECU choice if you're having difficulty with the injector DCs at varying voltages unless they're massively huge and your dead times set way off.