Bought these but have not received them yet. So I don’t know what kind of shape they are in. There should be 6 2900mah Panisonics inside. But they are pre-used, so buy at your own risk.
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http://www.ebay.com/itm/140854801627?ssPageName=STRK:MEWNX:IT&\_trksid=p3984.m1497.l2649
Once you get it do you plan on testing it? Based on your tests I may order some... :D
Price is now $14.25 
I also bought a pack when the price was at $9+. We shall see. Seems to be taking a long time in getting here.
At the moment I have no way of doing discharge tests, so if I did they would be unscientific. I’ll can post starting/end voltage though.
Ditto for me. I just got a lux meter and my next purchase will be a hobby charger for testing battery capacity. I have no battery tester right now. I do have a DMM. I do have a test flashlight that I use to test batteries, starting with 4.2 volts and the noting ending voltage after 30 mins. So far it seems to be a good indication. Then again, I was surprised with the lux meter readouts. Some lights were exactly where I expected they would be in terms of brightness, but others —- I was way off. Epecially in ceiling bounce tests.
Got mine today. Pack was in very good shape. Looked unused. EZ open pack. Just peel back the edge and a minimum of wrestling later (and a few well-placed cuts with tin snips) and all the batteries were extricated. Less than 5 minutes. Could be a new record. Thinnest cheapest battery pack I have ever seen. Another couple of minutes of snipping and twisting and all the cells were out. (Remember to TWIST the tabs, not pull them. Pulling can deform the negative battery bottom, which is pretty thin metal.)
All cells were 2.43-2.49 volts. This is GOOD news. This tells me that the cells are in good working order, i.e. no dead low or funky cells.
The usual HORRIBLE Acer cement was removed with thumbnails and wooden chopstick edges. I recover ALL my cells with transparent shrink tube OVER the original label, so it’s okay if they are a little sticky because the new shrink-tube will cover that right up.
They’re cooking in the Intellicharger right now. I will run a couple in my test light against a known NEW 2900.
After playing with other Pan 2900s for a while, I find that they don’t hold a charge very well at 4.20 volts. They usually drop to 4.17 or lower, but seem pretty stable at that second voltage. But because of this voltage drop — although the output is great — I’ll be steering clear of the 2900s for a bit. Drives me nuts when I go to use a cell and it has fallen to 4.15. I know, I know. Not that much of a voltage drop, but I have light blue 2400 panasonics and the pink 2600 Samsungs that hold 4.20 volts for MONTHS. And the older panasonic 2400 light-blue-green cells are ancient at this point. 2800 purple samsungs also hold 4.20 volts for months. Don’t know what it is with the higher mah panasonics. Just don’t hold a charge like the older ones.
Still $1.66 for a 2900 panasonic ain’t bad. Now lets see whether they work or not. Hopefully PyTech will chime in when he gets his.
It's back down to 9.97
Maybe he's alternating the price. I ordered at 9.97 just before I posted.
71 cents more per battery at the new price.
Mine are still cooking and up to about 3.56 volts, which means they’ll start to heat up a bit until 3.85 volts, and then they’ll cool down for the home stretch. Actually I think it’s the charger that’s heating up and not the actual charging process. If I elevate the charger a bit off the counter by sticking something under it — and allow more air flow — there’s a lot less heat.
Are there 6 x 18650 in there?
There are six.
Within 24 hours of charging these to 4.20-4.21, they fall back down to 4.17. They may indeed fall lower, but I keep recycling them, hoping that they will stabilize like almost all of the other 300 or so li-ion batteries I have had the pleasure of knowing over the past year. But they don’t stabilize. They won’t hold a 4.20 charge no matter what I do.
Older panasionics hold a charge like no one’s business. I have ancient lime green 2000mah pack pulls that hold a rock-steady 4.2 volts for 3 months.
It isn’t just these used 2900s. The other 2900 gray panasonic pack pulls that I and other BLFers bought recently also will not hold a 4.20 charge. They just won’t do it.
On the good side, they put out more juice than any other battery I have. Low-light-output lights heat up when I use these batteries in them. (The emitters heat up —indicating higher voltage. The batteries themselves are NOT heating up.) Tailcap readings go up. I can actually verify increased brightness with these batteries in many lights over Samsung pinks and purples. I used a lux meter to measure the brightness.
But they just don’t hold a charge. I will now top off some of these and set them aside for a month and see what happens. I betcha they’re at 4.05 or lower after 30 days.
So, if you want a powerful battery for cheap, get these. If you want to take a battery from the charger and put it in the light and use it. If you want to be able to pick up a battery a month after you charged it and have it be fully charged, these probably would not be a good choice.
Hope this helps!
I ordered one of these packs for $9.97 hopefully I have good luck with it.
I have some brand new factory fresh ones that do the same thing. Voltage falls to the 4.17V area and stays there. Looks like it the nature of these cells… new or old. Perhaps if you charged them to 4.23 volts they would hold 4.20V. Anyway, the difference in runtime between 4.20V and 4.17V is around 1/2 a second.
**I should be getting mine on monday. at $1.50 a battery I wont complain at any voltage, plus these are 3.6v. dif chemistry? I think what is most important is runtimes. and hope to see some of those soon.
how to tell what cells are inside the pack?
after seeing this thread I browsed on ebay, but there’s no such information…
You pays your money, you takes your chances…
we know for sure there is 6 panasonic 18650 2900mah batteries inside you can see that info in the pic. And the poster above has received them .but as far as dom and actual parformance of those cells, that info is not fully known as of yet. At $1.66 a battery I’m willing to try my luck.
>>>>how to tell what cells are inside the pack?
>>>>after seeing this thread I browsed on ebay, but there’s no such information…
almost ALL (all) major-manufacturer laptop packs say country of manufacture for the cells and country of manufacture for the the pack on the pack. I think I have seen maybe one out of tens and tens of packs that didn’t say what country. If it says “cells made in japan,” then it has to be panasonic because sanyo doesn’t make a 2900mah battery. In fact, I’m almost positive that panasonic is the ONLY compnay that makes a 2900mah battery.
Obviously if it says batteries made in china, avoid it like the plague. But otherwise 5800 packs have to be panasonic.
As for other packs, cells made in korea will be samsung or LG batteries (all great batteries although the gray 2400 samsungs are not some of my facorites), but usually samsung in HP packs.
Made in Japan cells have to be Panasonic or Sanyo or Sony, all great batteries. Sony batteries are always in Vaio and sony brand laptop packs.
Hope this helps.