can low batteries = rough idle

[338edge]

So my question is can low batteries make a miss at idle?heres some info whats going on did my head gaskets and studs with egr delete put it back together and it seamed fine drove it 2hrs home stopped and left idling for 10 mins maybe check ficm the next morning every thing seemed to be good drove it yesterday all was good. Took it out this morning to do my picket duty and it is about -20c here so its was idling(for about a hour) and i notcie that my voltmeter was under 12v with headlights and stereo and 2 way radio on.when idled up it hesitated than had a rough idle after that.shut it off for 4.5 hrs wouldn't startjumped it and took it to do some runnig around it was idling fine went in to store and noticed the smoke again and was idling rough drove it home and was idling norm again. voltmeter said 14v well driving.
any ideas
thanks

[Fantom]

I don't know about the batteries causing a rough idle, but low batteries can kill a FICM and a bad FICM can definitely cause it.

[338edge]

So with low batteries would it give false readings when testing ficm. The batteries had 12.3 volts when I check them before testing the ficm.

[Fantom]

I'm pretty sure it should be pulling the same voltage even with a bad battery.

When you tested the batteries, you disconnected one of them first, right? One of your batteries may be shot and it's dragging down the voltage from the other one.

[338edge]

no never even thought of it i'm going to load test them.I had a battery light on for over 2 years but never had any problems till now I thought it might have been a ground but checked all the ones i could find

[Fantom]

The battery light is usually a sign of the alt going bad on you

[338edge]

How many volts should my batteries have just sitting there over 12 volts?

[Fantom]

I believe each cell is 2.1 volts. So with 6 cells it should be 12.6 volts.

***edit***

http://www.autobatteries.com/basics/voltage1.asp

HAHA, I was right 2.1 volts. The little chart on this page says if you're showing 12.0 volts your battery is at 25%

[338edge]

Thanks fantom that's what I looking for one reads 12.3 and the other 11.90

[338edge]

How many cca should they be