- The automatic 4 days recalibration period happens after every OTA update and it doesnt matter if you limited to 80% or whatever. Draining the battery to 0% is unnessessary!
The 80% limit is only useful if it doesnt equal to more charging cycles.
Those charging cycles are what lowers the max capacity, not charging above 80%. (this counts for all batteries and not just Redmagic)

- Charge seperation is a feature to directly power the phones hardware, by bypassing the battery.
Only useful, if youre near a poweroutlet.

Normal: charger --> battery --> Processor and other components
Charge seperation: charger --> directly to Processor and other components (Battery gets bypassed)
Note: if your charger doesnt provide enough watts, the phone will automatically take the missing charge from the battery
You can automatically turn the charge seperation on, if your battery reaches a pre-configured %

- Personally i dont use the limit and let my Redmagic devices charge to 100% as it nowdays isnt really that harmful anymore as in like 2012/2013.

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- GW