Understanding Battery

Battery is a real-time measure of your body’s readiness, updating throughout the day as new Heart Rate Variability (HRV) samples are recorded in Apple Health. Unlike Recovery, which provides a static score based on your overnight HRV, Battery fluctuates throughout the day, much like an iPhone battery that charges and drains based on activity.

How Battery Updates

Activities like yoga or naps can increase HRV, leading to a Battery charge.
Intense workouts or alcohol consumption can decrease HRV, causing Battery to drain.
Battery updates only when a new HRV sample is recorded in Apple Health—if no new HRV sample is taken for a while, your Battery will not change.
Turning on AFib History in Apple Health increases HRV sampling frequency, making Battery more accurate.
You can do a Breathe session in the Mindfulness App to trigger a new HRV reading and update your Battery. But first, read more about How to Use the Mindfulness App for HRV Without Inflating Your Readings.

Battery vs. Recovery: What’s the Difference?

Battery much like your iPhone battery will charge or drain throughout the day based on your daily activities. For example, you may see an increase in your HRV after activities like yoga or a nap and therefore your Battery may have a charge whereas a hard workout or alcohol may cause a decrease in your HRV and in turn your Battery may drain slightly. Battery works when you have a new HRV sample in Apple Health. So for example if you have not had a new HRV sample for a while, it will not update. This is a feature where having Afib History turned on for increased HRV sampling would make Battery more accurate. Pro tip: If its been awhile and you want to check in on your current Battery level, you can do a Breathe session in the Mindfulness App to trigger a new HRV reading and update your Battery.

Recovery is how recovered you are upon waking up and ready to take on the day based on your most recent average HRV during sleep whereas Battery is your body's 24/7 state of training readiness. Battery is based solely on your HRV - a super metric! - and is not only measured during sleep but also throughout the day each time your watch records a new HRV sample.

Here is an example where you might use Recovery and Battery in tandem: Imagine you've recently been ill and, as a result, wake up with a low Recovery score (in the red). Throughout the day, you rest in preparation for an evening workout. By the time you're ready to exercise, your Recovery score from the morning may still be low, but checking your Battery can give you a different picture. Since your body has had time to rest and recover, your Battery may now show it's almost fully charged—signaling that you're ready to push yourself during your workout!

Why Does Battery Use Only HRV?

Heart Rate Variability (HRV) is one of the most reliable indicators of how well your autonomic nervous system is functioning. By focusing exclusively on HRV, Battery gives you real-time insight into how your body is managing stress, recovery, and overall readiness for activity. Unlike metrics such as heart rate or calories burned, which can fluctuate based on temporary factors, HRV captures deeper changes in your body's balance between stress and recovery. This is why we rely on HRV to provide a consistent, accurate measure of your readiness throughout the day, whether you're resting, working out, or recovering from illness, HRV provides the most direct insight into how well your body is recovering.

Recovery is how recovered you are upon waking up and ready to take on the day. The ‘Battery’ much like your iPhone battery will change throughout the day based on your daily activities. For example, you may see an increase in your HRV after activities like yoga or a nap and therefore your Battery will have a charge whereas a hard workout or alcohol may cause a decrease in your HRV and in turn your Battery may drain slightly.

If none of these troubleshooting steps resolve the issue, consider reaching out to Athlytic support for further assistance.