Shonky, Shonky, Shonky?
They are no more than an AA rechargable installed inside a D cell sized case. Check the weight. Are the D-onkey (shonky D cells) 4-5 times heavier than a similar rated AA?
Panasonic AA Standard Eneloop batteries are rated at 2,000mah or 2,500mah for the high capacity version. From $4-$6 each.
There are genuine C and D size Nickel Cadmium (Ni-cd) and Nickel metal hydride (Ni-MH) rechargable batteries in the market.
The C size are very common in cheaper rechargable household products. Jcar do sell a generic brand rechargable D cell. Ni-MH
$49.95 for two rated at 9,000mah
P.s. A likely response of Energiser, Duracell to misrepresentation might rely on the mah rating being clearly shown on the packaging, and that the battery is supplied in a larger container so that it can be used in equipment requiring a D cell/s.
Shonky if they charge more than for the same rated AA battery. I’ve previously seen cheap plastic adaptor housings for sale to allow you to use your AA’s in a D cell shaped body!
Eneloop standard AA 2000mah
Energiser D 2500mah
Edit added RS components pricing.
$12.83 each. That’s right! 2 to 3 times the price of an AA battery with a similar power capacity?
Observe that price is from a reputable electrical trade wholesale supplier selling to a market that arguably should know better.