For anyone seeking to get the best possible life and performance out of their bike battery, reading the Battery University is a useful place to learn from.
At this time with the current types of Lithium cells, the faster the charge, the higher the SOC, the shorter the overall life span of the battery.
A good read can be found here:-
Discover what causes Li-ion to age and what the battery user can do to prolong its life
batteryuniversity.com
The following graph taken from that web site, demonstrates clearly as to why 4.2 volts was selected as being the best with regard to capacity and long term life, in cycles:-
Figure 5: Effects on cycle life at elevated charge voltages. Higher charge voltages boost capacity but lowers cycle life and compromises safety.
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I hope this increases interest in Battery Knowledge here on Pedelec.
Battery University is a really great place to gain knowledge, even though the knowledge will not cover any very new developments and chemistries, as quickly as I would like!
But it will help a lot with the currently, generally available batteries, and not just Li-ion!
Happy New Year to all
Andy