FYI - some 'new' Fujitsu laptop batteries

I have over 200 pack pulls at this point (need to give more away on BLF), and these were the best pulls ever. Also the easiest packs I ever cracked. Just twisted them and the batteries almost just fell out of them. No dremels and wrestling with needle nose.

For those of you having challenges with the glue, scrape off most of it with your thumb or the edge of a wood chop stick. The rest of the glue residue comes right off with a little veg oil on a paper towel. Then wipe the excess veg oild off with another dry paper towel. You can use alcohol or other solvents, but I find that they tend to smudge or lighten the printing on the original label.

Put the cells in a Trustfire single battery charger for 15 seconds or so to bump them to 2.5 volts or so (from 1.8-1.9), and then put them in the I4. I always give them a rest for 2-8 hours or so when they reach about 3.6 volts. Most low-volt pulls tend to heat up a little around that voltage for unknown reasons. After a rest, no discernible heat and then on to 4.2 volts. All charged and ready to go.

You’ll probably need to cycle them 10 times or so before they hold a 4.20 charge reliably, at least in my experience anyway. I know these are unused and in near-perfect shape, because they zipped right up to 4.20 volts on the I4 without inordinately long charging times. Plus they went right to 4.2 volts and not 4.18 or 4.17.

These cells +REALLY+ need a layer of shrink tube over the original label. I use clear so I can see the original label. The original label does not cover the neg pole completely, so the posibility of a catastrophic short looms without shrink tube. Also, the cells can get nicked when pulled, so a shrink tube (available on ebay and elsewhere) will prevent more shorts through those nicks. And preserve the original label.

Be careful with using magnets on flat-tops. I did extensive testing. The magnets can migrate and can short against the battery compartment, and then you have BIG trouble BIG time. I put a small blob of solder on the flat tops, but don’t attempt it unless you can do it VERY quickly. Do NOT preheat the flattop. Just drop a smallish blob on there. Flux should get it to stick. At least I don’t ever have a problem. Just be careful if you do this. You must be super super quick. It doesn’t take much heat to melt the catalyst bag inside, and when that happens, you just armed the li-ion bomb. ;–0

Thanks again for the tip on these packs. Fantastic batteries. Like I said previously, panansonic grays are one of my favorite cells, only second to Samsung pinks and purples. Great find!


Thanks for the report, and the VERY detailed steps/information! Also, I think that it’s very nice that you’re thinking of sharing!


A 'catastrophic short' at the negative end will just bypass the switch and turn the light on. Sure, not ideal, but it won't cause a +20A dead short and set anything on fire, either.

If there are two cells in series and both have their negative short to the body tube it will be a 20+ amp dead short...

Jim -

Two main threads on the Defiant lights. Which did you get?

Defiant 3C / Defiant 3D


It was the non-ArmorMax “3C” one.

I was just out with it, and it is pretty cool, comparing to a couple of the other lights I have, including a Crelant 7G6CS that I just got, and it definitely is brighter, and out-throws the Crelant (and for that matter, all the other lights that I have).

Embarrassing, actually :(…


Well if you want safety the answer isn't to re-wrap the cells, the answer is to use protected cells in series cell lights. I suppose it could happen but the stars would have to be aligned just-so. Would have to be multi cells in series in an inline config and have both cells with a spot near the negative pole that both happened to touch through the anodizing at the same time... you get the picture.

Regardless of safety, the original panasonic shorty wrapper many times will eventually tear, along the bottom, from snagging chargers and battery cases and whatever. In fact, I have two of these 12 batteries going that way from just taking them in and out of the charger a handful of times. Before I covered them of course.

The label material on panasonics especially is pretty flimsy. Sanyos and samsungs hold up okay, but I cover ’em too. Besides protecting against shorts and protecting the original label, the shrink tube looks super nice …. and it allows me to write charge dates on the battery and to erase the dates when the writing space gets too full. With just a damp cloth. Sharpie won’t erase from the original wrapper easily without smudging the lettering on the original wrapper. I also write the original info (starting voltage, origin, dates, etc.) on the ORIGINAL wrapper and cover it with the clear wrapper so it doesn’t rub off.

Costs about 14 cents a battery and takes maybe 30 seconds to install with scissors and a heat gun.

But admittedly, I’m a wee bit anal about battery care and keeping track of each cell’s history. Having so many (i gotta get rid of some of these), there’s no way I’d remember which battery was which and bought when without writing it on the cell.

ohaya, you won’t regret getting if it is the Super Thrower. It has a XML that appears to be a T5 bin. It has lots of room for improvement (which makes it more fun for me) and you can go a lot of different directions with it. Check out the giant thread mentioned above. There are also other great mods that are in other threads Here are some of the easier things you can do to make it better:

  • Get rid of the resistance points. It has a lot of resistance. O-L have a nice tread on how to do that. Get so copper braid (don’t get Goot Wick). It will be your friend for decreasing resistance and for making small drivers bigger in diameter.
  • Change the driver. Here is a cheap one that is good. Get some extra amc7135 chips so you can increase the current. Tido and DrJones have threads on how to program this driver.
  • Replace the emitter with higher bin whatever else you like.
  • Replace the switch with a Judco 10amp switch.
  • Rig the light for parallel 18650’s. Be very careful doing this. You need to make sure you don’t short those batteries.
  • Replace the plastic lens with a glass one. Good luck finding one in that size though. In addition to making the light slightly brighter, it just makes the light feel more solid to me.

Best of luck. Take your time and change one or two things at a time. To me, it’s more fun to change the light over time as opposed to all at once. Oh, be careful handling reflectors. The reflective finish is very fragile on all of them. Something tells me you are going to be a great modder once you start getting the hang of it.

I did some discharge tests on these cells. At 1A they heat up to 40C. At 1.5A they get to 42C. At 2.0A they get to 45C.


FYI, I did discharge with a bunch of these, mostly in my Accucel @ 1.0 amps, and a couple in a TrustFire TR-003p4, and didn’t notice them getting warm much. Actually, the ones in the TR-003p4 did get a little (very little) warm, but I get that all the time with that charger, because the power supply is near one end, but the ones I did on the Accucel were not at all warm. By any chance, do you have any idea what the internal resistance is for the ones you have?

Can’t get over what a great deal these were/are. Have become my go-to batteries for now. Last longer than most of my other battries (even longer than four other supposed Pan. grays from china) Plus they fit in my little EDC gold Roche even with an extra layer of shrink wrap.

Have noticed NO heating in real-life use. Not even warm, except what is transferred to the battery by conduction from the emitter. Also the I4s really heat up with 4 batteries cooking and that heat also gets transferred to the cell itself. I know it’s not the cell itself because if I pop two out of the I4, they cool right down.

They do warm up a bit in some Trustfire 1-cell chargers I have, but I know that those 1-cell chargers are pretty aggressive. I only use them to top off cells when the I4s only take the batteries to 4.18 or so.

Thanks again for posting this deal. I don’t need any more batteries but I’m glad I got these!


I’m glad they’re working out for everybody.

You know, we probably should have coordinated the purchases, cuz I think someone said that they thought that seller figured out that we were all buying them (I did email him, but never mentioned why I bought them, nor that others were interested). Then again, if we did that, they’d probably have been gone before anyone here had a chance to jump on them :)…

The charger I mentioned is a 4-battery charger like the i4, but the power is to the side, instead of on top of, the batteries, so the battery that’s nearest the power end always gets a little warmer. I usually try to just charge 3 at a time, leaving that one slot nearest the power end empty. Just a precaution.

Edit: P.S. I just got a Jetbeam i4 pro last week, and was wondering: The +/- contacts seem a little weird. They’re “round” so I have to be careful when I put the batteries in, otherwise, they’ll sometimes slide off of the contacts, and end up kind of at an angle. Has anyone else noticed that? The TR-003p4 I have doesn’t do that. It’s kind of fun watching the lights on the i4 blink though (I really have to get a life :)!!)…

Around 46 milliohms.

I did not notice much heating when I was only discharging one cell at a time (at 1.5 amps the temp rose around 5C). When I started doing two in series was when I noticed the temperature rise.

If anyone is interested, I see that he’s got two more of these listed, but now he thinks he has a “hot” item so he wants to try to get more money for them now…- $ 22.50 .

That’s approaching $4 each for older cells…that’s out of the “good deal” window, so it might be a good idea to just wait at this point and let the auction expire.


Based on what someone (maybe you) said, that internal resistance seems “ok”?

I’m having a hard time coming up with a rationale that would explain that (heating up when in series). When their in series, and you’re doing a 1.0 amp discharge, the current through both/each of the batteries would, theoretically, still be 1.0 amps, i.e., the same as if you were discharging 1.0 amps with just one battery? I don’t understand why you’d get more heat in this case :(. I’m not doubting what you said… I just can’t come up with an explanation :(…

BTW, what kind of capacity (mAh) did you get on the discharge tests you did?


At that price, it’s probably borderline “not worth it”, given the risk that you might get a bad pack, plus the work youi’d need to extract the batteries, etc. Then again, they seem to be good batteries.

I’m sorry to hear that, but I’m also surprised, because he clearly told me he had “10” more of them. Sounds like he was holding out on me, and had a bunch more :)!

I took the dive too. It’s all your fault Ohaya. :stuck_out_tongue:
Should have a pack in a day or two. The 2900mah Panasonics do have a very good discharge curve when compared to a 3100mah Panasonic or a 3400mah Panasonic. The 2900mah seems to have a slightly higher voltage curve than either one when discharge at the same current. Less sag more current to the led in direct drive or linear regulators.


Sorry about that :(… I thought you got in on the earlier buys?

Here is a different battery that should have 6 2900mah cells. I took a chance and bought one. They have 9 left.

EDIT: I think it says “cells made in Japan”, but it is hard to tell. Top line on far right of label.