Would you believe it? My Nikon EN-EL 18C battery arrived from Germany today .....
..... I put it on charge and in less than 10 seconds it was showing charged ... I smelled trouble straight away and put it in the grip without EL 15 battery in the camera .... nothing whatsoever .... dead, I checked the menu for battery choice ... OK.
I tried charging again, same thing it showed 100% .... I then checked the voltage on the outer pins of the charger, 18 volts, about what it should be .... I then checked the voltage on the +- battery pins .... zero voltage , not a flicker ....
I rang Foto Erhardt (Amazons supplier and they said they would send another, I asked if they could test it before sending, her response was ... "Er ... I'm not sure" she said .... frankly I wasn't convinced that they could ...
Then I had a thought .....
Grays of Westminster (UK) is probably one of the most knowledgeable outlets of Nikon products in London .... so I rang them ..
I briefly told them my issue and asked them did they have a Nikon EN-EL 18b/c battery in stock?
He replied "we certainly do, the version C " ..... "are they compatible with shooting 9 Fps" I replied" .... "Yes absolutely, guaranteed" he said ....
I said " is it possible to test one before sending to me?" .....
"We only sell genuine Nikon EN-EL18c batteries which are tested and then charged before being sent out, I do it personally, because we have had issues with them if they have been standing uncharged for some time."
"Will you send to France" ...... "no problem whatsoever" he replied ... I asked the price and they are £179 + postage
So I will return the dud to Amazon for a refund and order one from Grays knowing it will be good ....
On topic:
I watched a video on power tool batteries and their issues ... the microchip coding that goes on in them is frightening .... the micro chip records every single electrical event, charges, current usage, no. of cycles, battery temperatures, pages and pages of incomprehensible codes and then some ..... The guy making the videos has spent literally years trying to fathom out and how to get round the codes ....
I don't expect anybody to follow this whole video completely, (I didn't) but it opens your eyes to what AI can do .....
https://www.youtube.com/watch?v=tHj0-Gzvbeo