I know you get what you pay for, but has anyone used these batteries before?
They are passable for something that is used sparingly (ie remote control).
Lasted a few hours in a wireless mouse, and a couple of days in a wall clock, all pretty much low consumption. Quite comical they're called 'Heavy Duty'.
A bit of a false economy really.

There is a huge market in cheap copies of batteries, I can only think that Poundland has accidentally bought some rip-off items.

Genuine Kodak xtralife AA cells have a capacity of 2700 maH and the AAA cells have 1050 maH both of which are quite respectable.

Kodak batteries are manufactured under licence by Strand but as Kodak was in very deep financial trouble the licence was probably obtained very cheaply.

I virtually only use rechargeable and use the JCB brand, some devices don't like the lower voltage of rechargeable, especially cameras that use 2 AA cells. The only thing with rechargeables is to NEVER let them get flat, it kills them.

Personally, I hate batteries. They invariably let you down when you need them and take hours to recharge or pounds to replace.

So I have replaced them in my portable hand drill with supercapacitors. This is a bit bulkier and requires a separate box to contain them, and holds far less energy. These are major disadvantages, but I find them more than outweighed by the fact that they do not lose capacity, degrade, and - by charging them at 40Amps- they can be fully recharged in 20 seconds.

I will, this summer, also use them in our narrowboat to start the diesel. At present there is a starting battery and a leisure battery. I can replace the starting battery with supercapacitors, which will give me two leisure batteries. The supercapacitors can be charged relatively gently from the two leisure batteries, along with the glowplug current, and will supply enough current (1200 Amps) for the short time needed to turn the engine over. Half a dozen of them - they are roughly the size of a 'D' cell - does the job a treat.

Here's a video of a Canadian guy who uses them in a car. https://www.youtube.com/watch?v=z3x_kYq3mHM

Do the super-capacitors have any balancing or protection?

During charging if they are in series there is a high risk of going over voltage on one of the series cells.

During discharge there is a risk of reverse charging which isn't critical on some smaller super-capacitors but larger ones are often sensitive to polarity.

Using super-capactors in high current applications severely limits their life and so can work out horrendously expensive if used regularly.

I designed and got made some little PCBs to protect them from overvoltage. These worked OK on the ones on my drill. Above a certain voltage (2.6v) they open a current shunt around the cell. In the ones for my boat they came with a PCB that did the same thing so I was saved from worrying about it. I doubt there is much chance of reverse voltage during discharge. They are all about the same value and are unlikely to go down to a very low voltage.

Like a twit, I managed to reverse the voltage on them for about 10 seconds the first time I tried to charge them and they all survived OK, so I guess they are not all that sensitive anyway.

They are specified to charge and discharge at 1200 Amps so I assume they will not be damaged by currents up to this. I can't measure currents of that size but I suspect that the engine on my boat takes a lot less than that anyway. They retain enough charge for perhaps half a dozen start attempt which implies perhaps about 200A.

I use 350F ones for the drill. For the boat, I got 500F ones which are a bit longer than a 'D' cell. They are all amazingly light though. From memory about 60 grams each (In both cases I have six in series).

My biggest problem was the charger for the drill. You can buy 40A switch-mode units on Ebay at reasonable cost, but they are current protected in 'hiccup' mode. When they are connected to the supercaps it looks like a short so they shut down and try again repeatedly. I had to open them up, trace the circuit and add trickery to make them supply 40A even into a short circuit, which was a right pain in the arse to do. Still, it's been working for some years OK now.

They seem to be extremely rugged. I once tried to discharge a similar one with a screwdriver across the terminals. It went to red hot, then yellow before I could get it off and was never the same again. The supercapacitor seemed utterly unharmed. They are supposed to work down to -40C but I haven't verified that.

Certainly a lot better than Ni-Cd and safer than Lithium.

Yes, that's an advantage I hadn't appreciated, all the capacitors will be dropping towards 0V at roughly the same rate instead of the more stepped drops of batteries that creates a cliff edge.

Bad luck on the power supply having had over-current protection rather than dropping into constant current mode. Reverse engineering switch mode power supplies can be a real pain, I guess specialist IC's make them a bit simpler than the discrete days of old.

The power supply reminds me that I need to dig out the parts I got for a 300W led lighting project, off-the-shelf Chinese constant current modules were far cheaper (and tidier) than anything I would build. I needed a ripple-free high power lighting source for slow motion video, unfortunately the camera developed a mechanical fault inside its lens/sensor assembly and I've not had a bench empty enough to do surgery as yet.

Much as I dislike them, I am forced to use batteries for a hand torch I use for after-dark dog-walking. The torch is a Chinese LED one and came with cheap 18650 batteries optimistically marked 3,400mAh.

They were nothing like this capacity, of course. An example of a Chinese sense of humour perhaps, but eventually, I got pissed off with them and bought some decent 'Nitecore' 3,400mAh ones at about £12. Expensive, but worth it. They seem to last forever without my having to recharge them.

I think you certainly get what you pay for sometimes. The difference is dramatic. I bought two and keep one charged and ready whilst the other one is in the torch. I am nervous about them nevertheless, and never leave them on charge at night or when I am out of the house. I also keep the standby one in a hopefully fireproof steel box sitting on a tiled floor.

A friend of mine is keen on radio controlled gliders, and told me of one of his colleagues who - whilst they were flying - stuck a lithium battery in his jacket pocket. A minute or two later, and he had smoke and flames belching from his jacket and was very lucky to get out of it without serious burns.

I really don't trust the things!

I try to get brand-name lithium batteries but that only reduces the risk, it certainly doesn't eliminate it. I charge my e-cig up in a box but phone is out in open. Camera's Chinese lithium batteries are charged in the shaver socket in bathroom where there is less flammable stuff around or beside me at the computer.

I get that feeling of "impending doom" with lithium, its not a matter of if, its a matter of when.

The last time I looked at Kodak batteries in Poundland I suspected there may be problem at that price. Sure enough, there it was in small print 'ZINC CARBON'. There is no comparison to a half decent alkaline battery.

DD mentioned JCB before. I have tried them and they seem ok, actually better than I expected. They seem to have their name on a number of things of late and I just can't imagine a production line for batteries running next to a line of diggers. So, I guess they found a good manufacturer to make them.

I dislike the idea of stuffing a car with Lithium batteries. It's not as if they are anywhere near energy dense enough anyway. Despite reading at frequent intervals about new exciting breakthroughs in battery technology, they remain at about one or two percent of the energy density of boring old diesel!

I read Ikea batteries are the highest rated. They’re cheapest, and they last the longest. If you see those battery recycling pods in shops, they’re always full of Kodak’s!
I only use rechargeable batteries as well, I’ve had the same ones for over 10 years.