Starting battery question

free radical wrote:
I dont have electrical gauge in the dash, so have bought small Gauge that plugs into the 12V outlet and displays the electric current quite accurately,
along with Yellow,Green and Red lights and bar showing battery state of charge..
The truck runs and starts perfect in any weather,
however the Gauge reads -11.99 and Red light on some cold mornings siting overnight,seems kinda low imo..
turns to Green and reads 14-15+ as soon as it starts,
then fluctuates up and down stays mostly Green and Yellow with normal Voltage,
though sometimes even at high speed the light stays Red and reads low Volts again.

Does the Alternator stops charging at some speeds and why,or is all this normal?

I'm not trying to pedantic, but this gauge does not display electric current (measured in Amperes) but voltage (AKA Electro Motive Force) measured in Volts.

You must be clear on the difference between voltage and current if you are going to use a multimeter as Shadow Catcher recommended. Measuring Volts on the Current (Amps) setting and vice versa will destroy the meter, or at least that function.

And Shadow Catcher is correct. Get and use a multimeter It can clarify a lot of puzzling situations.