I read somewhere that to charge to 4.2v shortens the life of the batteries by 50%. True?.
I have several chargers that charge @ 4.2v. One that charges @4.17v (Gyrfalcon).
I bought a few new ones the other day. And one charges to 4.21-4.23v.
I always use the lowest possible Amps. Like 1A for 18650-26650.
It takes time, but time I have, however.
I’m I helping my batteries charging so low?.
I can recharge @ .25v-.50v-1A-1.5A-2A-2.5A-3A-4A.
So maybe I can go a little higher in amp?.
Those were 3 questions.
My ignorance is so great, it’s a miracle there are only 3.
This article shows test data for battery lifetime.
But, to answer your questions directly; yes, you can increase life by only charging to 4.1 or 4.0 V, and yes, charging at only 1A for, say, a 3Ah 18650 will help it degrade slower.
Don’t discharge lower then 3.4 volts and it’ll help battery life by a lot.
I try to charge my phone at 30% and stop it charging at 80, this will almost double the charge/discharge cycles. I have an app installed that alerts me when charging reaches 80.