A full battery charge may last up to 8 days.
The PPG sensor in Kairos utilizes more energy when used on skin with higher melanin content or tattoos; hence the battery may last closer to 6 days as opposed to 8 days.
The Vital Science App will send push notifications as well as in-app notifications when the Kairos' battery goes below 20% and 10%.
To be safe and ensure the device battery lasts throughout the night, please make sure the battery is more than 20% charged before going to sleep.
To ensure optimal battery performance, AVOID letting your Kairos device to drain completely to 0% and leaving it uncharged for more than a month. Doing so will eventually cause the device to reach a point where it cannot be charged anymore.