Has he done anything more recently with regards to homemade batteries, or was it just a passing interest?
Since this article no longer has comment submissions on the page itself, is it possible to add a little something about the chemistry for bleach and safe handling?.
While the experiments are interesting, I can't help but notice significant deficits in safety that might cause anyone duplicating this (at different scale) to have regretful issues, proper chemical handling isn't really mentioned.
I'm no chemist, but I do have a working knowledge with some of these chemicals related to water chemistry (pools).
Bleach (NaClO) naturally corrodes (oxidizes) metal because of its strong electronegativity from Chlorine. Any metal vessel is going to rupture as a matter of time, potentially creating conditions where hazmat cleanup may be needed, where reactants need to be safely neutralized before byproduct cleanup can occur; this is not intuitive since dilution may not be sufficient; its highly dependent on the chemistry of the formed byproducts.
For example, Sodium by itself (metallic) reacts violently in air which is why its often stored in oil.
Many of the potential byproducts of the experiment are hazardous, or carcinogenic, and there is a possibility that some may recombine at the electrodes. No mention of needed PPE is made.
The voltage differential across two electrodes unless externally driven (electrochemistry) is almost always driven by redox reactions (reduction / oxidation).
The solution may recombine into chlorine gas on the reduction side. There are other reactions that may also occur.
While I don't see too many unaddress-able issues at the small scale, if someone scaled this up as-is to get an appropriate level of voltage/current, I'd be worried for their safety.
There's a whole series, "A Boy and a Motor", etc., all the way up to how to build your own model railroad from scrap, if you have the skills of a master machinist. Plus "Atomic Experiments for Boys". Really.
The Internet Archive has many of these.[2] "Shop Practice for Home Mechanics" is still useful, teaching how to do basic metalwork with simple hand tools. They cover lathe work, all the way up to how to make a crankshaft.
All this dates from an era before the availability of unlimited entertainment for timepass.
[1] https://archive.org/details/boyandbattery00yate/
[2] https://archive.org/search?query=creator%3A%22Yates%2C+Raymo...
Keep up the good work though!
For the record I vouched for your post above anyway, but if you keep doing that you'll likely get shadow-banned for spam so I think you really shouldn't be too heavy handed on self-promotion.