Batteries health added after this IPhone IOS version upgrades to IOS 11.3 (Beta) new function. Introduced batteries in detail most the problem of high capacity and capacity of peak value function.
Your batteries health capacity still has 84% , do not need to change battery, still can continue to use. 
Of batteries most what high capacity points to is opposite the batteries capacity at new battery, when you buy new mobile phone, when beginning to use for the first time, batteries capacity is 100% , this also is to examine a kind of method that your mobile phone is the two mobile phones that others has used.
You use a mobile phone normally, should charge periodicity is achieved 500 when, your mobile phone batteries is highest should maintain 80% in initiative capacity.
Introduce like malic official net, fill quickly for convenient, fill slow maintain life. Charge to be used as far as possible later fill slow, tiny stream stream charge, prolong battery service life; Be being filled quickly is cost in order to harm battery life. 
Clear what we should understand so is to charge periodic, batteries of malic mobile phone uses lithium ion cell, with charging periodic means works, this means you to be able to charge at any time, next graphs charge namely periodic sketch map, had used the n of 75% by day e.g. you, you fill cell in the evening 100% , the following day you used the n of 25% again, so these two days of total discharge volumes were achieved 100% , your mobile phone finished to charge with respect to accumulative total periodic. 
Batteries of Apple lithium ion is being finished many charge after cycle, 80% what can hold primitive batteries size at least, the batteries that says you so is fast be close to lowest to ask, do not want to change first temporarily.
