Some 18650 battery advice required

Batteries and Chargers Rechargeable Batteries
1

Hi all,

I am sure this may have been asked before so forgive my newbie repeatition.

I recently purchased a set of 4 Panasonic GA 18650 3500mah batteries. I seemed to have had trouble charging these fellows. I used a Littokala 4 bay charger that seemed to take an entire day to charge and even then, the charger was telling me that they were only 50% charged. It was after I thought they were charged, that I started to replace currently in use Panasonic NCR 18650 B 3400mah batteries. To my shock, I noticed that the 'new' 3500mah batteries were 2 to 2.5mm longer than the original 3400mah Panasonics. This new uncomfortable fact would mean that the new 18650 set would have trouble fitting in to the flashlight bays, the tail cap would have trouble closing now - to tight. What seems to have happened was that I had unknowingly purchased a set of protected batteries, where the set I was already using were unprotected. I now have some questions which I am hoping you chaps have the answers to.

1) Are all protected 18650 batteries a few millimeters longer than the unprotected version?

2) Why isn't the size differential made more clear in the product advertisement of either version? I say this because both protected and unprotected variants use the same product type code, i.e. 18650.

3) Why since the difference in length is so significant, isn't each version given its own product code to make each type easily recognisable? And why isn't there a different code for flat top version and buttion top version? For example, use 18650 for unprotected flat tops, 18650/1 for protected flat tops, 18650/2 for unprotected button tops and 18650/3 for protected button tops.

4) Why don't flashlight manufacturers state which exact type of 18650 battery each of their flashlight models should use, flat vs button and protected vs unprotected?

5) Why don't flashlight manufacturers state which 18650 battery output each of their flashlight models should use, that is, 2000mah, 2200mah, 2500mah, and so on?

6) When a battery is protected, what is it protected from or what does it protect?

7) What advantage or material difference does a higher rated battery output make to the actual use or operation of a flashlight?

8) Is there likely to be a significant difference between the Panasonic 3400mah and the 3500mah versions and if so, what is it?

9) What is the highest rated battery output that is genuinely delivering the stated output? For example, I know Nitecore offer a 5000mah 18650 battery, but is this a genuine output or marketing wishful thinking?

10) Is there or there preferred chargers for these types of batteries or will any 18650 charger do the job regardless?

11) Anything else I should know about or consider when selecting 18650 batteries?

Thanking you in advance.

2

Many queries here. I think you should read some article first,…
Anw, experienced members will answer your questions I guess. I can only say a few things.
What you call “output” is not really the output but the capacity of a battery, measured in mAh (milliamp hour).
Maybe you confuse capacity with voltage?
Both of them usually do mentioned by manufactures.
Protection is an electronic circuit that protects the battery from over charge/discharge. You can see one in this thread.
I hope you’ll get all the answers you looking for.

3

Does your charger show current? A four bay would devided its maximum output among the slots in use. So a 2a charger would charge 4 slots at 500ma or less. I can see it taking a while. Not knowing what you mean by “entire day”.

4

Hi,

1) Yes, the protection circuit (PCB) can add roughly 2-3mm to length and more if you add a ‘button top’ into the mix.

Cells come from the manufacturer naked and with flat tops and are intended for institutional users (laptop makers, tool makers, E-bike makers) who will design their own battery management systems (BMS) for charging/safety purposes.

2) 3rd party vendors add either the PCBs, button tops, or both and they’re all over the map and do as they please.

3) Li-Ion vendors expect their clients to have a basic understanding of what-is-what, I guess? The better ones do provide helpful info.

4) Along the same lines as #s 2&3, there are just too many variables out there to be specific.

5) We really care more about matching the current draw of a particular flashlight mode, to a cell’s current handling abilities, than we care about a cell’s gas tank size, as it’s a more important/critical factor.

6) Most PCBs protect against over-charge in volts, over-discharge in volts and too high a discharge current in amps.

7) Much like pumping water into a house, when things get to too high a pressure, things can go dwanky on you.

8) The Panasonic NCR18650-B (3400mAh) cell can handle say a continuous 5A current draw and the Panasonic NCR18650-GA (3500mAh) can safely handle a continuous 10A current. That’s a big deal for many modern lights.

9) “Output” in current delivery? There are cells from Samsung, Sony/Murata and LG that can output 15A, 20A and upwards of 30A continuous.

10) Xtar, Nitecore, Opus, SkyRc and Liitokala are all quality brands or chargers.

11) You really need to read a heck of a lot more—like weeks and week’s worth and get a quality digital multi-meter (DMM) to help you verify things—it’s almost mandatory.

Chris

5

OEMs produce flattops, unprotected.

Someone Else™ adds protection circuits and usually overwraps them to cover the sensing strip that runs down the side.

As a result, they will be longer because of the protection circuit and button-top (how much longer depends on the size of the protection board and BT) and thicker (because of the strip and additional wrap).

Some lights can fit both unprotected and protected cells just fine.

Some lights can’t.

Some lights actually need button-tops, whether protected or not.

Some creepy lights even require their own “proprietary” cells.

Getting lights and cells to play nicely together is often on the buyer, like it or not. When the light mfr sells/includes its own cells, it’s good to look at what they are (BT/FT, protected/unprotected, etc.) and either buy their cells or do your homework to buy compatible cells.

6

Thanks to all who answered and big thanks to ChrisGarrett and Lightbringer for particularly detailed answers. I think I'm going to be OK to use those 3400mah Panasonics on the torch I'm expecting soon. Thanks again - I'll have to find a book on the 18650 battery and all its configurations.

7

What happens is, if you try to use a current capacity beyond the battery’s capabilities, it might try it but not be up the light spec you wanted, or it may decide not to allow that setting based on voltage drop.

What some high-lumen light companies do is offer a suggestion.
The BLF A6 for instance states (somewhere) that it needs 8 amps to produce its highest setting.
So you would get that battery, if you need that - though it would be expensive.

I do not want to spend the money so my turbo does not activate.
It does not hurt anything, at least in that particular light.
Others might go ahead and run the turbo setting, though it might overheat the battery and shorten its life somewhat.

8

also - USUALLY there is a tradeoff between max energy storage (mAH) and peak current capabilities.

you cannot usually maximize both at the same time.

if you can, it will cost 10x what a normal battery does.

9

Actually, on lights that use FET drivers, like the BLF A6, it does matter that you use a high-drain cell even if you don’t use the turbo mode.

I did some testing with a light that uses a FET driver (Astrolux S42), using low-drain vs. high-drain cells. I can’t recall my exact results, but it was something like the light was 60% as bright at full turbo, and 70% as bright on all other modes. So, while full-turbo output is harmed the most by using a low-drain cell, all the other modes are harmed as well (unless the light uses a 7135 chip for low modes).

That indicates to me that the low-drain battery is still being stressed. It’s average current drain may be well within its specs, but a FET driver pulses that battery at high current all the time. Output of the light is simply controlled by how long those pulses are.

That said, I still don’t worry about it, and will happily use low-drain cells in my BLF A6’s. Even at full turbo. Yes, it’s hard on the cells, and the light isn’t as bright, but the lower output has a nice side-effect of giving it more run-time. The BLF A6 is a high-drain light, but it’s not super-high like some of the multi-emitter burners.

Anyway, in summary, always get high-drain cells if you can. Or at least fairly-high. The Sanyo NCR18650-GA is a cell where you don’t need to compromise (much) on either drain or capacity.