Pièce inconnue de la batterie

There are two primary reasons you may see this:

1. The battery in your iPhone was replaced by someone other than Apple or an Apple Authorized Service Provider, who would NOT have access to authentic Apple Parts, so the battery is not an Apple Battery OR....
2. The battery in the phone is failing, which would be unlikely on an iPhone released 5 years ago.

We don't know anything about the history or your phone. Did you purchase a used iPhone? If yes, it likely had the battery replaced with one not from Apple. Or you may have paid someone to replace the battery, who was not Apple or an Apple Authorized Service Provider. Typically, Apple won't touch an iPhone which has been tampered with by unauthorized service shops.

Or, if you are the original buyer of the phone, open Settings > Battery > Battery Health - if its health is 80% or lower, the battery is failing and it's time to pay Apple to replace the battery in your iPhone.

Did you mean The battery in the phone is failing, which would be likely on an iPhone released 5 years ago?

LD150 wrote:

Did you mean The battery in the phone is failing, which would be likely on an iPhone released 5 years ago?

Uh......um......er.........YES. And it's what I get for not having had my first cup of coffee at the time I responded. Note to self: Be caffeinated before posting!