adafruit_support wrote:That adapter would be the charger. Does it have any specifications for current?
Ok, after taking a closer look at it - here's what it says:
Kodak Adapter K20-EC
Input: 100-240V~50/80Hz Max 0.2A
And.....there's a car/mains charger for the batteries (without using the USB cable) which I hadn't noticed before which reads:
Input Voltage: AC 100-240V 50-60Hz
Output Voltage: DC 4.2V=600mA
(for both of the above the symbol isn't a normal = sign but has the lower line as 3 dashes).
Does this help you at all to understand the problem (as it means nothing to me!)?
Also, the batteries I used were two brand new (and unused) Duracell batteries and so that shouldn't be part of the problem.
Thanks for taking the time to help.
Something else I just thought to mention. When the MintyBoost is plugged into the Zx3 it stays on with zero battery charge and so the MintyBoost is providing enough power to run the thing but just isn't charging the batteries (with it either on or off).