126 new battery?

[Snowman]

Hello all,

1985 500SEL with 130k miles died while on the road today. The interior lights dimmed every time I tried to start it. Gave it a jump and then it ran for about 2 minutes and stopped again. The battery seems to have drained itself.

Should I try a new battery? The current could be old, the old owner put it in, so it's at least 5 years old (most likely a lot more).