14.2 or 13.8

[toy2008 1]

Sometimes in my truck voltage reads 14.2 and other times it 13.8. Stock 130 amp alt and a xs d2400 under hood. And big 3

[ricksi30 923]

Do you have a question?

[toy2008 1]

Why is it one or the other? Why is it not always 14.2?

[ricksi30 923]

Why is it one or the other? Why is it not always 14.2?

Things as simple as the temperature can have an effect on your voltage. Ac, headlights, gps, rpm's, your volume knob on your stereo etc...voltage is constantly changing as demand changes.

[toy2008 1]

Is there a time where alt is charging battery then its not.

[smashedz28 110]

If the vehicle is on it should be a higher voltage. Like rick said...just about everything that lights up or moves in your car affects voltage. 13.8 isn't bad

[ricksi30 923]

Is there a time where alt is charging battery then its not.

I don't believe so in most regular gas vehicles but I could be wrong. An alternator does put out less amps at lower rpm's though.

[shizzzon 461]

Is there a time where alt is charging battery then its not.

 

An alternator is not designed to charge a battery.  It can only maintain them.

There is no regulator to properly charge batteries off of an alternator.

 

So it outputs a constant current that the battery will accept.  It will decrease the amount of current to the battery because of the battery's doing but will never stop.  It's like a trickle charger that never stops.

 

The only reason why it doesnt kill the battery under long durations is because of the lower voltage.

 

Now, if you do what some other people do and FIX their regulators to a set, for example, 14.8v, then put their battery under the hood where the ambient temp around the batt is warmer than in the car and you go driving for long distances, it will swell the battery from overcharging.

 

Temperature and charge voltage go hand in hand. Higher the temp, lower the voltage needs to be.

 

Alts have a Cold and Hot rating.

 

They are typically only cold the first 2 minutes when car is first started.