My daughter bought a 2009 Rogue last August ( 120,000 miles).
For preventive maintenance, I decided to change the water pump, Alternator ( Duralast), coolant hoses, etc.. ( I did this last August).

Now my daughter says when she starts her car for the last 3 days, the battery light is on for about 15 seconds and then goes away.
This only happens in the morning when the temperature is below 15 degrees.
When she goes to the store and comes back to the parking lot, it starts without the light coming on.

Can a battery that is starting to go bad cause this issue?
I am almost inclined to get a new battery and see what happens.

Or the fact that the light comes on at any time is always the alternator?

Could be the belt, but if not, it's the alternator. The battery can't cause a no-charge condition.

Doubt it is the belt. The belt is new, and I also put in a new tensioner.

Could it be that it is so cold, it affects the alternator and once it get up around 20 degrees or higher, then it is OK?

Rockhoundrob wrote: ↑

Sat Feb 13, 2021 11:12 am

Could it be that it is so cold, it affects the alternator and once it get up around 20 degrees or higher, then it is OK?

Sure, silicon parts can malfunction with temperature just like anything else. The battery light is basically driven straight off the internal regulator in the alternator, so no matter how you cut it, the alternator is saying there's something wrong. There's only one other possibility that occurs to me, which is the alternator clutch. That's hard to check but they usually make noise when they're failing. It can't be a wiring issue because any open circuit would turn the lamp off and not on.

OK, I'll wait til next week and see what happens when it warms up.

It only gets below 20 degrees about once every 5 years or so.
So if the problem goes away, I'll chalk it up as being unusually cold.

As long as it only comes on when she starts the car and only for less that 15 seconds, then maybe I won't worry about it.

Rockhoundrob wrote: ↑

Sat Feb 13, 2021 12:26 pm

As long as it only comes on when she starts the car and only for less that 15 seconds, then maybe I won't worry about it.

That's probably the best idea. If it's actually failing silicon and not just misbehaving, it'll get worse and you can do an actual diagnosis.