MBP 2017 battery charge count is 165 and Service Recommended

Cycle count is not the defining metric for replacement; capacity is. Once the capacity drops to 80%, Apple recommends replacement. There is no acceptance criteria for cycle count. The 1000 cycles is just an educated estimate; a best guess based on many factors.

New batteries that fail have a cycle count that's very low. But new-battery failures are not an impossible situation.

Why? I can think of, at least, four reasons:

1. It is a replacement battery ... and it is defective.
2. It is the original battery ... and it is defective.
3. There was a liquid spill that made it inside.
4. The method used to extract the battery count was inaccurate.

Tesserax wrote:

1. Why? I can think of, at least, four reasons:

It is a replacement battery ... and it is defective.

2. It is the original battery ... and it is defective.

3. There was a liquid spill that made it inside.

4. The method used to extract the battery count was inaccurate.

5. The Mac was stored at a high temperature with a full/nearly full battery, and the battery was damaged as a result.

There's always the possibility of random behavior or premature loss of capacity. It happens. But certainly there are things that can prematurely kill a battery early such as prolonged excessive heat or physical damage such as shocks that damage the battery. The battery is probably the weak link in most portable electronics because it's relatively delicate.

A battery can also be damaged if it is left completely discharged for any length of time.

Keep in mind your laptop is five years old. Batteries age no matter how well they are managed and cared for.

Unfortunately it is not always easy to determine if "Service Recommended" is a battery with diminished capacity, or a battery with a hardware failure, or both. Unless you are having issues with the battery, then just ignore the message until you have problems with the battery.

Excellent addition! Thanks.