I noticed that when I use my nitecore dual bay charger the batteries charge in about 4 hours (21700)
But if I push the bottom negative terminal with my finger towards the battery the battery takes less time to charge
Does the charger spring strength impact the charge rate? Is having stronger springs better? Reduced resistance or something?
Possible. Higher R, thus more IR drop. Might drop the voltage that the battery actually “sees” and starts tapering off earlier then tailing off that much longer.
Eg, it goes from CC to CV when applied voltage hits 4.20V, but with a good solid contact the cell might be “seeing” 4.18V at its CC value when it switches to CV, but with the higher IR drop it might only be “seeing” 4.10V when it switches over.
Bulk charging in CC mode happens pretty fast, and CV mode can take a looong time, sometimes even longer than all of CC mode as it sloooowly tails off.
I wondered why, say, a 3000mAH cell that only needs maybe 2000mAH could charge at 500mA, so 4hrs, but takes 5-, 6-, 7hrs 'til it’s done. That might’ve been the reason.