Samsungs charged to 4.30v, Sony at 4.20v? If you don't have a 4.30v charger, run the Sonys down to 4.10v and do the comparison again.
The Samsung –28A from the white Acer Aspire packs is a 4.3v cell? This was never mentioned in the original thread for those packs. My i4 terminates at 4.16v.
This is the original thread for those packs, and the 4.3v info is in multiple posts on every page. Go back to page 1 and start over.
…
<_<
Well pooh. I feel silly now. 
Outside of a RC-pack charger, are there any affordable 4.3v li-ion chargers available? Or do I need to post a WTS ad?
Theoretically how much would I damage the –28A by using this charger from Fasttech?
I saw the cottonpickers charger while looking about, but I don’t have $50 to spend on a charger. But a charger that will charge to 4.35v is okay to use with the –28A?
4.35v is too much for these cells, just like 4.25v is too much for 4.2v cells. These will work fine at 4.2v but they lose a little capacity (~200mAh IIRC). I have several of the Samsung 28As that I gave to friends that have been using them at 4.2v without any problems. Don’t fret it!
There is also the $5 “budget” option (which I am using): CC/CV board
There are lots of good examples on how to set this up in that thread. This one is mine.
TGT, I have the charger you linked, the light changes colors at 4.3v (on mine) making it easy to get the right voltage in there.
Cool, oh, and HJK did a review of it. And Fasttech bundle it with batteries too. Seems like this charger definitely needs attentiveness though.
You actually have to work at it to get to 4.35v, like leaving them in there overnight, everything happens very slowly. Also, the 28A has a + or - .02 or .03v range (don’t have the spec sheet handy) so there IS some wiggle room there.
Very often I just charge them in my i4 though, they work great from the 4.19ish volts it goes to.
Well, I can’t find that charger anywhere else, so I’ll take my previously good luck and play the Fasttech lotto again it seems. 
Just don’t order batteries with it and it’ll probably make it to you just fine… 
Just bought another AS09D70 laptop battery, for storage should I just leave them in the pack or crack’em outta there and charge to 3.6v or so? Thanks!
Aren’t you even curious whether they are good cells? Might as well open it now just to check the cells out and then charge them to 3.6v (50%) for long term storage.
IMO, definitely pull them and charge. I bring my samsung pack-pulls up to 4.30V resting then let them sit for a week before rechecking. If they hold 4.28-4.30, they’re good. All my cells are in a rotation and get stored at 3.7 - 3.8V. I Have not found a bad one yet, which is pretty amazing.
Mine was $17
Some more for sale cheap. Look here;
Came across a couple more of these packs for sale on eBay for $16.
I think I have enough packs for right now, so when I come across intriguing new, old-stock laptop pack deals I’ll be posting them to this category, on my blog (and on BLF, when I have a chance)
The above is quoted from RMM a few posts up. Not sure why it’s not showing up right.
Lifetime of the cell increases when charged to a lower voltage. Back in the day, common knowledge was: charging a LiIon to 4.2V would give you approximately 300 cycles while charging them to 4.1V would give you closer to 800 cycles. I’m sure charging 4.3 V cells to 4.2V would only increase its lifetime. (some laptop brands have an option to charge their batteries to a lower voltage to increase battery life)
That sounds inflated. The rule of thumb I’ve seen is that life doubles with every 0.1v reduction in charge termination voltage. Still an improvement, but 2x is significantly less than 2.66x.
Its worth keeping in mind though, that the rechargeable battery is just part of a system. A 0.1v reduction in charge voltage results in a sacrifice of about 10% amp capacity every cycle, which means more charge cycles, which eats up part of the increased cycle lifetime. It also results in a greater reduction in energy capacity, because 280 mAh at an average voltage of 4.25 (beginning of discharge) is 1.19W, where as the same 280mAh 3.2v (near the end of discharge) is only 0.88w. Moreover, the current required to deliver a given amount of power also goes up, which means more heat and stress too. (The current/power relationship isn’t an issue with a linear regulator, it is with a switch mode regulator).
A bigger issue might be philosophical: Is the user supposed to serve the battery, or is the battery supposed to serve the user?