Test / Review: Panasonic NCR 3100mAh

I just completed testing the Panasonic 3100 with a protection circuit . Length = 69.1mm Dia = 18.2mm

Lets check out the performance in 4 of my flashlights :

Flashlight Battery Sanyo Battery Panasonic
SST50 2.5A 2.1A
MF XM-L 4.7A 3.8A
SF XM-L 1.85A 1.8A
MF XM-L 4.7A 4.4A

Now when doing the discharge test for capacity , there was an interesting turn of events : Lets check out the graph I made .

@ 1A discharge , I got about 2500mAh capacity to 3v , and a further 350mAh when discharged to 2.5v

@ 2A discharge , I got about 1857mAh capacity to 3v , and a further 985mAh when discharged to 2.5v

@ 3A discharge , I got about 1326mAh capacity to 3v , and a further 1376mAh when discharged to 2.5v

Here you can see where in the voltage range the capacity or energy is coming from at various discharge rates .

As can be seen , as the discharge rate increases , more of the energy is pulled from bellow 3v . [ Due to voltage sag under load ]

Now this might be a very slight problem if you have a single 18650 flashlight , thats a bit of a hotrod , and you want to run it for as long as possible on high . [ Boost driver or well regulated ]

Now most of my lights , actually dont run when the battery gets bellow 3v , so ?

Now if your running a multi 18650 , I dont see a real problem depending on where the voltage on the driver may or may not turn the light off . [ Actually this may be more of an issue ] Sorry , I was tired and lots of homework to do , see link .

https://budgetlightforum.com/t/-/8223#comment-163066 Read here !

Thanks very much for the review! Frontpage'd and Sticky'd.

Very useful Old! much appreciated. So are these results in anyway linked to the PCB or would the unprotected version have the same results?

I nearly bought these for my Solarforces as well, glad I didn't. I got the Sanyo.

Marc.

Old, where did this cell come from and what does it cost?

Oh, and thanks for the review - the new graph format is interesting.

Thanks old!

These came from Ebay ...

But I would assume all the HK dealers are getting from the same source ...

I dont think the discharge has anything to do with the protection circuit ..

Its is simply battery related :

The Panasonic 3100 is a laptop battery , and was designed to be safely discharged to 2.5v ... Other batteries are designed to be safely discharged to 3v or 2.75v and deliver most of there energy above 3v , but looks like the Panasonic 3100 is a different animal .

And discharging at lower AMP's did not show this up .. Kind of glad my old charger bit the farm now .

And these cells are intended for battery packs , so its the pack voltage and application that matter .. So for laptops , these might be great ,

In a 3 x 18650 set up , these batteries could be fantastic , or even a 2x18650 set up as long as the cut of voltage is lower , like 5v

In a high powered single 18650 set up , hmmmm , maybe not the best choice .

http://www.ebay.com/itm/290687595099?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649

Here is a link :

Well Old, I must say, thank you again for this review. I have seen a review based on the non-protected version and it got glowing reports. But they did not test it as you have done here. Which is vitally important as most people seem to have single cell lights. I can only imagine there may be a lot of unhappy people out there who have bought the various different versions of these cells. If I read your graph right, my solarforce XML draws 2A and will not work below 3v, Therefore these could be the worst cells possible. They may even struggle in my BC 40, as that seems to cut off at around 5.5v.

Marc.

Well ... Whoa !

Ok what I would take from this is the voltage sag under load , which manifests itself @ 3A discharge rather dramatically .

Ive got so much on my plate these days ! Sorry about that ,,,

Ok a flashlight is not going to maintain a 3A discharge to 3v , thats not going to happen , unless its one heck of a boost driver .

Whats going to happen is the voltage sag may affect output @ higher current draw .. But this battery discharges well enough ..

But still , less voltage sag = better output ..

I have to admit that the graph I made , while interesting , may mis represent the battery ... As the discharge was constant current ...

And what the voltage sag will do is drop you out of regulation earlier ...

So to put some perspective on this ,

Say your light starts discharging @ 4A fully charged , by the time it hits 4v even that may have dropped to 3A , and by the time you hit 3.5v your current draw might be down to around 2A , or even less ...

Let me get out one of my early run time tests :

OK found the Panasonic 2900 run time test :

4.2v = 3.53A Start

4.01v = 3.5A 5 minutes

3.92v = 3.11A 10

3.84v = 2.65A 15

3.77v = 2.46A 20

3.7v = 2.21A 25

3.64v = 2A 30 minutes

3.6v = 1.81A 35

3.57v = 1.75A 40

3.54v = 1.67A 45

3.51v = 1.56A 50

3.48v = 1.44A 55

3.45v = 1.34A 60 minutes

3.41v = 1.12A 65

3.38v = 1.06A 70

3.34v = 0.93A 75

3.32v = 0.84A 80

3.3v = 0.78A 85

3.27v = 0.68A 90 minutes

3.24v = 0.6A 95

3.19v = 0.47A 100

3.11v = 0.33A 105

3v = 0.22A 110 minutes

This is how a battery would be drained under normal circumstances , now where these batteries may be at issue , is as stated , voltage sag under load = , multi battery lights , 2 x 18650 , due to increased voltage of the combined batteries , the light might run fully regulated for much longer [ the reason 2 x 16340 was so popular for a long time ] , thus with 2 x 18650 the batteries may be under high current draw for longer , and this would mean they will voltage sag , possibly at the cut of point [ light wont run to protect from over discharge ] and due to the voltage sag you may not see a full discharge [ run time on high ] , as at 3A you lose almost 50% to bellow 3v ...

So if you have a high discharge 2 x 18650 , it might reach the drivers protection point up to 50% faster ..

Single 18650 lights are the ones that may not be as much affected due to the diminishing returns that come with running single 18650

Sorry guys , too much home work , n' stuff ...

I think I need to go to bed earlier , another early post , 00.17AM ...

OK Old, But surely there is still a problem reaching the full capacity of these cells. If my Solarforce turns off at 3v, I am going to miss quite a bit of mAh. Am I not?

Marc.

Some mAh will be lost , yes Maybe around 15% ...

A buck boost driver would drain it nicely ...

OK, I see what you mean about not being able told sustain a draw of 3A. But I thought the driver would draw more Amps as the voltage drops. Is that not correct?

I am by no means an expert, so I could be misunderstanding how they work.

Marc.

If it's a boost driver - yep, that's how it'll work, but most single-cell 18650 lights have linear drivers, which decrease current with voltage drop.

Ah ok. But does that mean the torch becomes less bright as time goes on? If so, would that not be a little like an unregulated torch?

And does that also mean that these panasonic could still be a little short on capacity in two cell lights? If so, it does sound like the Sanyo 2600 are hard to beat.

Marc.

Only after voltage at battery drops below Vf of LED, while it’s same or higher than Vf, brightness is regulated.

Nope. Check this graph:

Most two-cell lights are in 1A to 2A range and work from 5.5V (and up), so you're getting 2.8 - 3 Ah from those cells.

Because of the decreasing power demands as the voltage drops , you will get most of the energy from the battery ...

My bad , its in multi cell applications where you may run into issue as these lights can maintain regulation for much longer due to the voltage range of the combined cells ...

How to simplify ?

One thing is the emitter , lets call it 3.5v voltageForward , as long as your voltage remains above 3.5v , you have some semblance of regulation , so the reality is your light may fall out of regulation [ depending on all the variables involved ] around 3.6v or 3.7v [ again depending on the variables ]

Now a multi cell light [ lets call it 8.4v ] , the battery voltage is way above our needed 3.5v , so the driver bucks [ lowers voltage ] to the required amount ...

Now this means you can maintain regulation till the cells themselves are almost depleted [ again those nasty variables ]

So its in multi cell lights , where this discharge curve will most likely affect owners , especially in high powered applications ..

And single cell lights will most likely , simply behave normally ..

Which is why I put that example of a run time test there , How well a single cell light maintains regulation depends on the battery driver emitter combination and the current draw .

I have a light here for review , and the company claims excellent regulation , which I will test :

OK Back from school

Where was I ?

High powered lights !!!!

Lets say you just got yourself a 5 x XM-L wonder Rod !

And lets say 3.5v x 2.5A to be on the reasonable side :

Thats 8,75Watts per emitter [ this is the energy for the emitter , never mind driver loss etc ] , and 5 emitters = 43.75Watts

Thats some 43.75 Watts that the batteries have to supply , at the very least ...

If we do some maths , then we will see that 2 x 18650 @ 8.4v would need to supply 5.2Amp , that is a some what unreasonable expectation ..

Since many of these lights go 3 x 18650 or 12.6v , lets try the math again ...

That comes to 3.47Amps , a more reasonable expectation ...

Still , bear in mind the light may have a safety cut out at 5.5v - 6v , so the 3 x 18650 set up is going to drain hard without some inbuilt safety ..

But with the 2 x 18650 , we can see , that this battery is going to be pushed hard [ to the wall ] , be it multi XM-L or SST50 or SST90 , there will be issue on high as the voltage sag will really affect run time [ on high ] ..

So the battery may be fine in one application , not so great in another , and maybe fantastic in another ..

This may be a case of , too much information :

To summarize: With time to think and analyse

Single cell use = Should be fine

2 x 18650 = Varies depending on use / current draw / the mode your in

3 x 18650 = Should be fine as the voltage is much higher .

I have ran about 10 test on these cells HERE they are good cells, but will not work in all flash lights due to the button top and not all lights can go to 2.5 volt or 5 volt in multi cell set up's as an example my lights cut off around 3 volt and 6 volt so i can not use all the mAh of the batteries.

Marc, i have just done full runs on my XinTD C8 to cutoff voltage and the Sanyo's recorded 54minutes vs 76minutes from my unprotected Panasonic3100. The test is not completely fair as i used the Sanyos with no cooling vs the panasonic with fan cooling. I will do the Sanyo run again with cooling. Edit: test complete, Sanyo with cooling = 55minutes on same cell, so pretty much no difference, Panasonics run considerably longer even at 2.8A draw of the C8

Both fully charged on the same Xtar charger, confirmed with fluke voltage measurment. I have a couple of protected Pannys on order for DX so ill test these also if they arrive this year...

Yes that is a big difference! Are your Sanyo's un-protected? I know it doesn't make any difference, I just wondered. Thanks for this info, very useful.

Marc.

Yes unprotected, both Sanyo's and Panasonics from Intl-outdoors so im confident they are genuine. The Sanyo's are great cells, best matched set ive ever bought. See my stickied post in the Batteries forum, im updating it a little, my KK is discharging now...

https://budgetlightforum.com/t/-/4891

Yes I saw that post it was excellent. The reason I asked about the sanyo's is that I have just order a couple from Kaidomain and wondered if they had a button top. They seem to, but a very small one. But you can answer the question for sure.

Once again, thanks Jeansy and keep yourself dry where you are!

Marc.