Originally Posted by
dougmc
http://www.dealextreme.com/details.dx/sku.19770 $6.35 for two unprotected cells.
http://www.dealextreme.com/details.dx/sku.5790 $8.01 for two protected cells.
I have not torn my pack apart, but I'm guessing it's made of the two protected cells (with four cells total.) (The protection here refers to a tiny circuit that stops the cell from being discharged or charged too much. It sits at the end of the cell and is pretty easy to miss.)
If I were to make my own packs, I'd probably buy the unprotected packs ($12.70 total), solder two cells in parallel, then another, then put those in series, adding a balancing tap in the middle while I'm at it, and then I'd use my balancing R/C charger to charge it. I'd also scan DX's site for a 2s protection circuit, one that will cut off at >8.4 volts and <7.2 volts or so -- not essential, but a good idea. It's also possible that they sell something that does balancing as well -- if so, that would remove the need to use my balancing charger at all.
You can buy four battery shaped objects for 16 bucks. You may, or may not, get a lithium battery. It might work. It might not.
DX doesn't give a flying leap about quality; neither do their suppliers. If you do get four working cells, you won't get four cells that are well matched, and they're even less likely to stay matched after a dozen charge cycles.
It's exactly that sort of crap cell that's causing problems in the magic shine (and lots of other POS cheap chinese electronic junk, too.)