Qi charger – more details

So I found a 2.4A USB charger:

Already tried a 3A model but it was a dual USB port and no info about each port limit, I suspect it is 1.5A for each.

So I started charging my EV3 again, with ev3dev running. But removed the USB hub and the CRS 4.0 dongle, left just the Edimax wi-fi dongle. Also disconnected 2 large EV3 motors I had:

162666

163 mA (43 mA less than previous attempts)

Is started from last night “full” charge with same Qi emitter and receiver (but EV3 OFF), 7.23 Volt

7232133

After 45 minutes it charged to 0.1 V more (7330466). After that it slowed down but still charge up to 7350466 exactly 1h57m after.

Then it started to behave strangely again, discharging to 7262466 after another 35 minutes. Then it stayed there for the next 20 minutes.

Both RED and GREEN lights are ON (EV3 battery). And the Qi devices seem  coupled.

7.26V is just 0.03V more than last night “full” charge result. Perhaps it is the best I can get with the boost circuit’s output trimmed to 9.02V.

If that’s the limit, then using a better USB charger and/or reducing EV3 current consumption by 43 mA helped. But it still isn’t enough for a mobile robot, adding a couple of motors and sensors will raise consumption above the nearby threshold and the robot will just discharge slower until it shuts down.

I wish the EV3 had a Real Time Clock and wake up function. Crazy ideas accepted 🙂