10K and 1K resistors gives you (5 * 1 / (10 + 1)) = .45V. That's kinda an odd combination; you'd want something closer to 3.3V so you have more precision over the full range. 10K and 10K would give you 2.5V which leaves good headroom for slightly greater than 5V batteries. And that takes you down to .25ma for the divider.
But when you have a slowly-changing voltage you're trying to read it's OK to use larger resistances. Use two 47K resistors and take the current down to .05ma. Then you're at 4.5 years.