To get the app to make a health estimate, you must add a minimum 20% to its capacity, but AccuBattery isn't all that accurate unless you do full charge cycles. Doing that puts more stress on the battery and not recommended for long term battery health.
Ah, ok. I've had this phone about 3 months or so, and it was a year old before I got it, so, just curious. Since I can't just pop the back off and get a new battery down the road.
Which is why it's no longer advisable to drain full cycles. For example, I'm running a 10,500mAh extended on my phone since it does have a replaceable battery. If I keep to the usual 40-80% same, AccuBattery think's it only has about 50% health. If I let it drain and do a full 0-100% charge cycle (going until actual charge cutoff, not unplugging as soon as it hits 100%), it thinks my battery is still at over 90% health.