[vanderZwan]

> electroplatting gold and silver jewellery.

Electroplating requires a much higher voltage than whatever these batteries would have put out. Apologies for the meme-y video, but Electroboom explains the issues quite well regardless:

https://www.youtube.com/watch?v=XcFOOfqfx3s&t=5m30s

[saneshark]

A few of them in series could increase the voltage.

[vanderZwan]

Already addressed in the video - another YouTuber put ten oversized versions in a series and barely got a single LED to light up.

[unnouinceput]

So put a hundred more in series and you get bigger voltage. If 10 of them lit a LED, which needs something like 1.5V then 100 of them would give you 15V. Car batteries are 12V or 24V, depending on the car model/size, so 100 or 200 in series and you get that covered.