Sorry everyone, I can't change the title. Yesterday I thought it has something to do with the traction control but I found out it isn't.

Yesterday was very cold. When I drive on highway, I saw "services charging system soon" message several times. It went away when I speeded up. When I took off from highway I saw the message again.
It won't start this morning because the battery has no much power left.

I saw this message last winter but I didn't pay attention. I never saw it again until yesterday.

Is it a battery problem or a alternator problem?

Thank you!

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1998 Cadillac Sedan DeVill, 220,000Miles
replaced blower motor in 2004
refilled A/C in 2004
rebuilt door switch in 2005
rebuilt TP sensor in 2005

Weak battery? Corrosion on the cables?

Weak battery? Corrosion on the cables?
Thanks but I don't know.
Yesterday was very cold. I guess the weather broke something.