Battery weight a good indicator of quality / capacity ?

if you order cells from a not fully trusted vendor (trusted, like RMM, and others) or a vendor in China who had no idea what is actually shipped or sold (like many on AliExpress) that is advertised as being an A brand cell, weight certainly is something that can give away if it is fake.
Also when presenting your case to AliExpress or paypal, it is good to be able to show a much lighter cell then the official specs state for example. (I must be really lucky, only the no name or Ultrafire cells I received were poor in terms of low mAh and higher internal resistance, all branded ones tested OK so I have not disputed cells)

Getting a charger that does just a little more then charging (for example, my Littokala Li500 for $15 shipped without adapter) can give you some more info, they may be not all that good at giving you a 100% result on internal resistance and mAh but using the same charger on all cells surely give you a good idea on those things and also over time, since the faults are present in each measuring, a decline in mAh or elevation of internal resistance can be seen easy.
And well for $15 having a quad bay charger capable of charging a lot of different cells is a good deal in itself IMHO
Edit clarified a bit :wink:

“if you order cells from a not fully trusted vendor (like RMM)”

OK, I’m confused. When did RMM become not fully trusted? I’ve ordered from them and always thought they were a first class vendor.
Just asking.

Depends how you read it, he meant the other way.

Don’t feel bad ‘RichardinNC’, I thought the same thing until I reread it 3 or 4 times. :wink:
I think (hopefully), that CRX has the correct answer. :+1: … :wink:

@CRX: Thanks for posting those picts. When Ricflair told about a small capacitor inside an hollow cell i had a hard time to believe it - no offense intended. Such a blatant scam is mind boggling. :open_mouth:

Lol clarified, when posting I was certain it was clear, but well don’t want people reading it several times before getting it, its just that BLFers usually and generally seem rather smart, keen and sharp :wink:

If it is too light, it is definitely weak in all areas. (Talking to you, “UltraFire”, though I’m sure others perpetrate this too, I have at least one light/verified crappy UF*)
If I remember correctly, it is like 20g too light.

But as others pointed out, it’s pretty cheap to add sand, so that doesn’t work.

And a battery that is good but old, will be weak but not weigh any less.

wle.

Amazing posts! Thanks for the photos. I sure am learning a lot here.

So tell me, when they put a capacitor inside a battery like that, what will the test results be from a charge/discharge test?
I mean, I assume it will have less capacity, but by how much?

In other words, could I have a battery that seems to test reasonably close to expected results, but still only have a capacitor inside?

And if it tests reasonably close, what’s the problem?

Sorry if these are noob questions….but I’m a battery noob

Thanks

Oh, and maybe (again, I’m a noob so this could be silly) but……

Why couldn’t a chart of some sort be created listing what the average or expected weight range might be for different cells of different capacities?
For example, shouldn’t the weight of an authentic18650 of 2400mAh capacity fall in a certain range since it also claims to be Li-Ion chemistry?
My thinking being that if it’s the chemistry it claims (inside) the weight of that capacity for a given chemistry “should” be fairly uniform?

For example, I just weighed an UltraFire 18650 that claims 5000mAh (lol) and weighs 35 grams.

I’d bet the weight of a real 3400mAh 18650 weighs more than that.

Granted, a smart Chinese battery faker (vs an authentic battery maker) will add sand or whatever to make up the difference, but maybe a lot of Chinese fakers are also lazy fakers and don’t do that?

So at least in some cases, a quick weight comparison could be handy in cases where the faker didn’t fake good enough?

Finally, if you shake a battery and can feel the weight shiting or hear movement, it’s probably a good bet you got a fake right? lol

I don’t think it’s capacitors being used, just very small lipo cells with capacity anywhere around 100 - 300mAh judging by the sizes so maybe 5-10% stated capacity if you’re lucky :laughing:

Ahhh…so the capacity would be WAY off?
thanks

I just bought a 10 pack of cheap cheap UltraFire 18650’s ($1.00 each) off of ebay and I guess I got lucky because they all consistently tested at 700mAh which is at least usable in my small 1000lm Cree flashlights.

i don’t really believe a capacitor could simulate any battery… first it would not have a constant voltage curve, under a load, a capacitor starts dropping proportional to the current, batteries do not do that. capacity would vary with the value of the capacitor, but it’s basically 1/2 C Vsquared… very small for any capacitor they could fit in the can, compared to a battery…

Ok. That helps. Thanks.
I wonder if the charger/tester would even try to analyze it?

it might look like a faulty battery.

with a small energy storage capacity, it would appear to “charge”[reach final voltage] very fast.

but the stages a li battery would go through, would not appear correct, so it’s hard to know how a smart charger would interpret it.

which is another reason to suspect that it never really happens.

Also, supercapacitors are not cheap either.

a charger isn’t going to say “hey this is a capacitor”. because it is so unlikely. it might say “i don;t think this is a battery” or just “error”. or “one charging stage looked funky to me, so i quit trying.”

Well we don’t want to arm them with better faking information! :laughing:
HKJ’s reviews give all the specs of cells and there is consolidated versions of his tests in my sig link post.

Any movement inside a cell tells all, check out HKJ’s disassembly of batteries threads too. There is no space for anything to move around in a properly made cell, it’s pretty much a long roll of tightly packed films end to end.

” Disassembly of cheap 18650 battery”:Disassembly of cheap 18650 battery

Disassembly of some UltraFire batteries

Disassembly of UltraFire 9900mAh 18650 battery

Oh dear, not that lucky, these are most likely old used laptop cells or whatever which were good at some point maybe five years ago or so, you’ll learn in time to toss these and get proper good cells but we can’t rush your learning curve with our advice. :wink:
It’s amazing how many of us started out buying this crap, myself included but at least you’ve come to a place where you will learn about it.
Why have 700mAh capacity and safety issues when you could have up to 3500mAh, peace of mind and far superior performance. For that $10 you could have two or three cracking good cells.
Not giving you a hard time, just saying :wink:

Old laptop cells are a good example of something a weight test would not detect.

Additionally, they are the most likely source of fakes.

Cells get old without selling, they get cheaper and cheaper by the month til someone buys then and then voila!

“9999 MAh 18650s! 10 for $10”

wle

I think the best bet now for every one is to buy a charger with capacity tester they can be found for cheap. They will give you a rough estimate.

Amazing how they rejuvenate and improve themselves with time and a new wrapper :laughing:

yes.
real cells are around the 44-48 gram ballpark.
way lower than that means junk and corrosive drywall dust.