6 Panisonic 2900mah Batteries for $10

They hold their charge quite well. There is zero real world difference between a cell at 4.20V and 4.17V. And once you put a load on them, there is less than zero difference.

Well, yeah, there isn’t much diff between 4.17 and 4.20, but for me, there is a diff between 4.20 and 4.10 volts. For me that’s 25% of the usable voltage. I rarely use a battery below 3.80 volts. For many of my lights, that’s a substantial drop in light output.

With the new xml2 lights, once I’m below 4 volts, I’m in abyssmal output territory. And not some doesn’t-matter output percentage reduction. I’m estimating L2 lights lose 25-35% of their output below 4 volts.

But as I said in an earlier post, maybe the 2900s stabilize at 4.17 volts. I bought three new packs on ebay, three cells from fasttech and one used pack. I charged five cells (one from each of those sources) to 4.20 volts and will track their loss over 30 days. Surprisingly, two cells almost immediately dropped to 4.17 volts within 24 hours, but now they’re back up to 4.2 volts!!! The other two have dropped to 4.18 volts.

And also as I said, tain’t throwing the baby out with the bathwater. The cells outperform all my others …. and at over 300 batteries in my collection at last count (even counting the 30 I just gave away here on BLF), that’s a lot of cells to beat. So if I have to cook ’em the same day I use em, that’s what I’ll do. Not a big deal.

Once under load, just about any cell will be below 3.9V The energy between 3.9 and 4.2V is pretty much an illusion… sort of like the difference between fumes in a gas tank and the actual gasoline.

I usually start from a corner with something sharp like a knife and working around spreading the pack aprart carefully not to stick anything inside it too far that might make a short. once apart
you have to be very careful when separating the cells esp on the positive ends. all the batts are soldered together with metal bars which are sharp and will cut right in through other batteries’ shrink wrap if you bend and twist it the wrong way. you could get seriously burned if you get a short. just take your time is best advice I could give

Ubehebe

Do you really live in Death Valley?

>>>>>Once under load, just about any cell will be below 3.9V The energy between 3.9 and 4.2V
>>>>>is pretty much an illusion… sort of like the difference between fumes in a gas tank and the actual gasoline.

I guess my lux meter is reading an illusion in 20-35% reduced light ouput when the voltage falls from 4.2 to 3.9 volts. :wink:

Hey Top cat. You won the battery giveaway. I sent you a PM. Didn’t you get it? Please send me your snail-mail address so I can send you the batteries.

>>>>>Ubehebe Do you really live in Death Valley.

Yes, I live in a tiny tiny ghost town (population: about 30 on a good day) in the mountain/plateau above Death Valley National Park. I’m 80 miles round trip from the nearest gas station and store and 190 miles from the nearest home depot and wal-mart :wink:

DV sink is now officially the hottest place on earth. It used to be the second hottest, but they found that the supposed hottest place was not Libya as previously thought but really is DV. They made a mistake taking the reading back in 1932 or whenever. I don’t know how they could possibly decide 80 years later that the reading was wrong, but that’s waht they say.

However, I am crazy but not nuts. I usually try to beat the heat in June-August and escape to The OC, Calif., but I’ll be back in DV at the end of August, early Sept., when it starts to cool down.

WOW I WON!!!

No I didn’t see the note, but I just got it thanks, That’s great!!!

If I hadn’t replied to this thread I may not have seen it at all…

One of life’s funny little quirks, eh?

Yes, I’ll send it out to you.

Just curious. Do you have internet service there?

>>>>>Just curious. Do you have internet service there?

Until a year ago, all we had was dial-up. And not even 56k dialup. Because of the bad phone line, the fastest dialup we could get was about 24k. It was slower than watching grass grow.

But recently, Hugesnet satellite internet became available. It is expensive, abysmally slow and has all sorts of horrible latency and other technical problems, but it’s faster than dialup. So we’re using that. It’s better than nothing but just barely. It also has quotas, so watching youtube or other vids is inpossible.

Back to $9.97 so it’s time to give these panasonics a go. Is using a sharp chisel an approved way to disassemble and break the spot welds on the tabs? Or, do you just snip the tabs and leave the leftovers on the cells?

>>>>Is using a sharp chisel an approved way to disassemble and break the spot welds on the tabs

Jeepers NO!! You might bend or dent the cells and puncture the bag inside. Plus, they’re welded on so the welds are actually part of the metal at this point.

You need to separate the tabs from the weld points. Just take needle nose pliers and grasp the tabs and twist more than pull. They pop right off. The battery casngs are VERY thin and you can deform or “pop out” the bottom if you pull too much on the bottom (neg). You can be pretty rough with the positive terminals. But same thing. Twist and pull.

There will be some weld left behind but I dremmel that off VERY CAREFULLY. The battery casing is very thin. You don’t want to weaken or puncture it. Or you can just leave the weld spots. It’s just that they tend to be sharp and can cut uncareful fingers.

Hope this helps.

On disassembling these packs …. I wear gloves because the plastic can be very sharp. But these are the cheepest packs I have ever seen. I just grabbed an edge with needle nose and just pulled em apart. Just be very careful not to dent the cells or short anything. If you get an arc that doesn’t stop or feel the batteries start to get hot, toss em far away and take cover. I’m not kidding. They +WILL+ catch fire in a hard short within seconds. Seconds not minutes. Most just flame and burn but some do blow up. Disassemble the packs outside. AND BE CAREFUL!!! If you get a flame out, do NOT breathe the fumes. They are HUGELY toxic and supposedly can ruin your lungs for life.

O.K., no sharp objects around the cells! I just would have thought the twist and pull method would deform or tear the cell wall, but I trust your experience. Will definitely perform operations outside. Thanks for the tips, I haven’t tried the cell scavenge routine before.

>>>>>O.K., no sharp objects around the cells!

Didn’t mean to jump all over you. Just wanted to stress that there is always the possibility of some bad stuff happening to the unwary.

Hard to explain about the twisting and pulling on the tabs. Start with the positive terminals and get a feel for it. Like I said, the positive terminals are pretty solid and can take some serious wrenching and pulling before they even begin to deform. The negative battery bottoms are different and a little tricky, but you’ll get the hang of it.

Nothing’s perfect. Some spot welds hold well and might pull out the bottom a hair, and others just pop off when you look at them. I find that the combo pull and twist method works best but maybe someone has a better way to do it. If they do, I hope they chime in. Not like I went to a class to learn this. There may be a ebtter way. I just don’t know what it is.

Maybe in 1 of 6 tab pull-offs, I get a slight SLIGHT bump on the battery bottom, but I just tap it on some wood to push it gently back in. If I really rank the bottom, which has only happened maybe 5 times in hundreds of batteries, I chuck the battery. :-(.

See, there’s a bag inside rolled up like a pastry, filled with catalyst. If this tears, it will ruin the battery and could also result in the famous “venting with flames.” The chances of this happening are really slim, but everyone playing with packs should be aware of the dangers.

**when I first saw this I thought they sent me wrong pack. notice the top pic says only 5400 mah. anyways right to the left (bottom pic) it says the correct specs. which is the 5800

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6 2900 panasonic grays. starting volage was 2.63 - 2.69v. charging at the moment
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>>>>>>>>>>6 2900 panasonic grays. starting volage was 2.63 – 2.69v. charging at the moment

Yee ha!! Way to go. Similar voltage to mine. They should be fine. canNOT beat the price. Thanks for the pix!

Interesting about the two mah figures. I think I mentioned before that quite a few times I get cells overrated for the mah rating, i.e., a 4800 pack might contain 2600 or 2800 cells instead of 2400s. But I have never seen a pack with cells rated less than the printed capacity.

BTW, I havent said it yet but thanks Ubehebe for the heads up :slight_smile:

she didn’t go down without a fight. she’s one tough hombre compared to most, my hands were a lil sore to begin with so I was taking my time for once. and for once I didn’t even see a spark.

>>>>>I had to get one myself for my SRK to replace the crappy Chinese cells I currently use in it.

I am mister unprotected cell, for a number of reasons, but even I will not use unprotected cells in a multi-cell light. If one cell kabooms in a multi-cell light, they ALL kaboom in what is called a thermal runaway. There are arguments that because it is thermal and not electrically triggered, that protected cells don’t make that much difference. But I think anything you can do to stop a thermal runaway chain reaction from happening is a wise move. Hence, I ALWAYS use protected cells in multi-call lights.

>>>>>are my posts not showing up??

>>>>>hey guys what about other packs he is selling?

Maybe if you narrowed down the packs in question and posted one or two links of the best buys here? Sorting through 18,000 laptop packs on ebay to find you the best buy is quite a chore. Many times the ads do NOT say they are for 5800 packs, so we would have to read 18 million ads.

The info for determining which packs contain the panasonic 2900s are in this thread.

To recap:

1. Cells made in Japan (says on pack).

2. Cell total output = 5800 (no other company makes 2900mah cells in japan except for Panasonic). Cell output should be visible in the photo of the pack on ebay.

3. All packs containing 2900s so far have been for Acers.

Hope this helps.