eBay Seller: red_planet_trading
New Genuine Dell Precision M70 80WH 7200mAh Battery 310-5351 312-0279 312-0336
The seller has more than 10 available.
I just checked and the seller has 3 listings for this battery: just search his items-per-sale for ‘80WH 7200mAh Battery’
If anyone buys one, does it come in a sealed Dell box?
I am not the seller. I just saw them for sale on eBay.
I didn’t mean I thought you were the seller.
I was just directing to question to anyone buys one.
no thanks…
Thanks for the link 
Said 7200 mah so wouldn’t they be Samsung 2600 mah?
I posted about this same pack from the same seller a few months back (blog post, too lazy to find the forum link). I didn’t buy it myself, but someone who did reported that some of the cells were pretty darn low (under 2v). I don’t think they ever posted any discharge test results. My guess is that this new old stock is pretty old.
They're 9 cell packs, likely 3S3P. 7200/3 = :beer:
The cell capacities inside a laptop battery pack are calculated as follows:
11.1V/3=3.7V ===> That tells us that there are three 3.7V cells in a series in order to increase the voltage to 11.7V.
7,200 mAh/3=2,400 mAh per cell ===> This tells us that each 3-cell row of cells is also connected in parallel to two other rows to increase the capacity 3-fold from 2,400 mAh to 7,200 mAh.
To double-check our math we read the description of the battery posted by the seller which tells us that this is a 9-cell battery (3 rows of 3 cells per row).
When cells are connected in a series, the voltage of such a battery bank increases times the number or cells in the bank but the capacity of this battery bank remain the same. For example, three 3.7V 2,400 mAh batteries connected in a series would create a bank with a capacity of 2,400 mAh and voltage of 11.1V.
When cells are connected in parallel, the voltage of such a bank remains the same but the capacity increases times the number of cells. For example, two 3.7V 2,400 mAh batteries connected in parallel would create a battery bank with a capacity of 4,800 mAh and voltage of 3.7V.
I have never seen cells in laptop batteries connected only in a series or only in parallel. They are usually connected both. For example, a row is connected in a series to increase voltage, then each row is connected to one or several other rows in parallel to increase capacity.
I hope this helps.
Nice to know, eas. Thank you. I did not purchase from this seller and did not have your info. I do not doubt they are new old stock since they are batteries for something like Dell Latitude D500 laptops which were in use 5-7 years ago.
Yes, it does help, for some reason I was thinking 6 cells :8) ha, never mind my math is still off
I bought 2 of these packs and took them apart, a little more difficult than some I’ve taken apart, all came in at about 1.8 volts.
Batterys are light grey in color
LGDA2E18650
F2342809597
DH222D9A2
Charged batterys with an I4 to 4.2 volts
Batterys have been sitting for over a week and holding at 4.19 measured with a fluke meter
I’m no expert on batterys but these seem to be nice batterys at a good price.
Thanks for your feedback, Beachlogger.
Charge them for the 1st time with the lowest amperage your charger allows to recover as much of the original capacity as possible.
I never throw away any batteries from laptop pulls without attempting to charge them first, regardless of the residual voltage. I was able to recover over 80% of original capacity of laptop pulls with voltage as as 0.4-0.5V when I charged them with the lowest amperage my charger allows (200 mA).
The reason to pitch low-voltage cells is that they are more likely to develop an internal short, leading to thermal runaway, at some point, not because of concerns about capacity. Just because everything seems fine at first isn’t reason to think there won’t be problems later.
Some people pitch cells if they are below 3v. My cutoff is ~2v. From the information I have from Battery University, anything below 1.5v is in the danger zone.
So is this with all lion cells in general or used cells or never been charged NOS laptop cells, and if they do start to become a problem how does one know, do they heat up when being charged or is there some other telltale signs?