I needed six rechargeable AA cells for an old Hanimex potato-masher flash, which I bought cheap the other day to do some Strobist experimenting. I've only been buying low self-discharge ("LSD"!) NiMH cells for a while now, but I don't have six identical AA LSD cells spare at the moment, and I didn't want to drop the substantial extra amount of money to buy six more LSD cells for a flash that I'm not necessarily even going to use much.
So I hit eBay, looking for the finest, cheapest NiMH AAs in the world. And I won an auction for twelve allegedly-2500mAh "BTY"-branded NiMH AAs, for 5.5 UK pounds (about $US8.30 or $AU9.30, as I write this).
That one on the right didn't explode; I ripped it apart to see what, if anything, was inside. 'Cos it sure wasn't a 2500mAh NiMH cell.
I didn't, to be fair, actually expect these AAs to really have a capacity of 2500 milliamp-hours. Capacity inflation is rampant in the rechargeable-battery market. Even the big brands often seem to pump up the capacity numbers a bit, and it's perfectly normal for an off-brand "2500mAh" cell to have a real capacity of only 1500mAh or so.
That was fine with me, though, especially for less than ten bucks delivered.
(I think you even get the "off-brand PC power supply" situation, in which some dealers sell a range of cells specified from 2000mAh all the way to a truly audacious 3000mAh, but all of them actually have the same 1500mAh-ish cells inside the wrapper. DealExtreme, for instance, sell "2000mAh", "2300mAh", "2500mAh", "2800mAh" and, yes, "3000mAh" "Maxuss"-branded AAs, with the allegedly-higher-capacity ones priced accordingly. The user reviews suggest to me that you might as well just buy the cheapest ones. If there's a difference besides price and the printing on the label, it doesn't appear to be a large one.)
These BTY cells were much worse than I expected, though. I knew something was up as soon as I opened the package; the BTY cells are way too light. They weigh about 18 grams each, versus 29 grams for an old Sanyo 2500mAh cell, and 30 grams for a Sanyo Eneloop LSD AA. They're substantially lighter than the old worn-out 1650mAh off-brand cells still mouldering in the bottom of my Battery Drawer.
My Maha C-808M charger (yours, Australian shoppers, for $AU183.15 delivered from Servaas Products) didn't like the look of the BTYs, either. It did charge them, but flashed its "battery fault" error at the end, possibly because the charge cycle was over so quickly.
To their credit, the BTYs did run my flash. But not for very long. When I charged them again and hooked one up to a 0.9-ohm resistance (a horrifying load for an alkaline cell, no big deal for a rechargeable), I got a useful run time...
...of about 25 minutes, for a total capacity of maybe 350 milliamp-hours, with a following wind. (The terminal voltage also dropped to less than 0.8V immediately, even into this modest-for-a-NiMH-cell load.)
It was at this point that I disembowelled one of the BTYs. I was half-expecting to find a fractional-AA or AAA, or something, in there, but the casing was actually full of the normal Swiss-roll sandwich of metallic electrode and noxious-electrode-soaked separator. I'm not sure whether the BTYs are actually nickel-metal-hydride or mere nickel-cadmium cells; I don't think you can really tell by looking. They certainly only have the capacity of the ultra-cheap NiCds you get in bargain-store solar garden lights, though.
(There are honest dealers that sell these sorts of cells, by the way. Here's an ebay.com search and here's an ebay.com.au one that find one current dealer's particular description of them. I have no experience of that particular dealer, but they'd have to be pretty perverse to misdescribe low-capacity NiCds. Note that you still don't necessarily want these cells, even if you only need low capacity, because NiCds contain highly poisonous cadmium, and remain a serious disposal problem.)
Aaaanyway, I filed a PayPal dispute over this, and anticipated a long and painful experience. So when I got an e-mail from PayPal the next day saying the dispute had been closed, I of course assumed that someone at eBay had decided I was ineligible for a refund because it had been three months since the dispute was filed on the 35th of Octember and I still hadn't had the batteries X-rayed by a fully licensed Federal Hat Inspector while I whistled Dixie and a five-legged elephant painted my naked body with the full ceremonial vestments of the Ecumenical Patriarch of Constantinople.
But the dispute was actually closed because the seller had instantly knuckled under, and given me a full refund.
If there's one thing I've learned from reading The Consumerist, it's that whenever you complain about some crazy fee and they instantly reduce or waive it, you're always looking at a scam. (Well, almost always.)
And lo, searching for other people's experiences of "BTY" batteries turned up a number of reports astonishingly similar to, though blessedly less long-winded than, my own.
This guy tested a range of cells and found BTYs ranked equal worst. There are people complaining about them on DealExtreme (or, at least, giving them one-star ratings). Heck, there's even a Guide post on eBay itself that warns about them.
So, on balance, I'm not sure that I actually deserved to get my money back.
There are plenty of eBay dealers, including the one I bought from, who are still selling "BTY" cells. Some of them have taken the advanced camouflage measure of calling the cells "BT" instead of "BTY", but my advanced h4XX0ring skillz can still find them.)
Don't buy those batteries.
Oh, and how did I solve my flash-powering problem? Well, the awful BTY batteries do actually power it for a little while; for longer run time, I just yanked the six-cell NiCd pack from a giant robot bug I'm not currently using and hacked up a lead to connect it to the flash's external-power-input pins.
So now I can make a camera rig that looks even stupider than this!