Maximum possible file size and fastest charging speed?

[DrDarius]

(02-12-2020 04:52 PM)DrDarius Wrote:  I am going to take one of my Primes, drain the battery, and measure the charging current for the empty battery. But it may take a day or two to drain it, since I'm going to use a calculator to do it. I will post an update when I'm done.

It took shorter than I expected.

From the charger's standpoint, the important parameter is current drawn from the charger, not the current charging the battery. (If the charging circuitry is based on the switcher, they would not be equal.) So, for the measurement I used Ruideng USB current sensor connected between the charger and the calculator (rather than measure current flowing through battery terminals).

I let the calculator run until it turned off by itself. The battery voltage after it happened (measured on the battery removed from the calculator) was 3.061V. It well corresponds to standard 3.0V LiPO cutoff voltage.

The current drawn from the charger measured for the calculator turned off was 0.655A, thus slightly more than I expected. (This is the maximum current; it kept quickly dropping down, and after ten minutes dropped to vicinity of 0.5A.)

Thus, to make sure that the used charger is not overloaded while charging fully drained battery, it has to be able to deliver about 3.3W. Most of the small chargers exceed this value.