What "normal" charger can also be used to test capacity (like BT-C3100)?

Is that a typo or does it actually display 4.10V instead of 4.20V?

Where is the best price on these chargers ,? Thx

Typo. Should read 4.21V. Fixed.
It charges to 4.21V CV and also displays 4.21V during this phase. Which means it intentionally overcharges a tiny bit.

Right, thanks. Mine has already shipped. I will hook up my UT71D in logging mode and make some graphs of voltage and current once it comes.