No battery light, but the car is dying

[Supersam]

I am driving a 06 chevy cobalt with nothing more than h.i.d. lights and a system i just did a tune up on it and the car since then has randomly died on my twice. Need help its a friends car

[YelloEye]

Is the amp turning off when the car is off?

[Supersam]

everything is shutting off but then coming right back on and the car starts right back up when i put it in nutrual

[YelloEye]

It's dying while running? Whats your battery voltage at normally?

[Jmesl8er]

Doesn't sound good

[Supersam]

yes while i'm driving down the road but i am not sure of the voltage i'm really hoping its just in need of a new battery

[cobalt123]

alternator going bad?

[YelloEye]

Sounds like an alternator to me.

[Tuner923]

what did the tune up consist of?

[Supersam]

it was a simple tune up, just spark plugs, wires, air filter and oil change