Cheap Li-Ion batteries 8000mah on ebay?

Hopefully *only* when abused.

It's very difficult to come up with names that don't create unwanted associations in the mind (of a native speaker). I was helping folks come up with an English name for a new company last month- the names that I thought were good were (of course) already taken and most of the ones they came up with had unpleasant, unfortunate or sexual connotations that were difficult to explain. Complicated by regulatory limitations in some markets on what you can call your company, as well as just simply not being so close as to poach on another's name. There are companies that do nothing but this:

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, but doing a thorough job is not cheap. There are surely regional variations as well as variations from country to country, even those that nominally use the same language, especially where slang and association with regional events and entities are involved.

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Then, there are companies that are cheap, lazy, or both. A123 battery company was forced to change its name as part of the buyout deal and became B456: Apparently, they didn't want to waste any money finding a new name for essentially a place holder. Too bad a B456 is actually a fire extinguisher. Seeing a pattern here, I Googled for C789 and found a Fluke meter: Meanwhile, one of the founders of the original A123 company formed a new battery company, 24M to make cheaper LiIon cells:

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Jeff Liebermann     jeffl@cruzio.com 
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On a sunny day (Sat, 21 Nov 2015 09:53:48 -0800) it happened Jeff Liebermann wrote in :

Eh, let's see, from asm source: ; Lipo battery cutoff voltage in mV #define BATTERY_LOW_CUTOFF_VOLTAGE D'3100'

; Display will warn at this battery voltage level that battery needs charging #define BATTERY_LOW_WARNING_VOLTAGE D'3200'

This is what I measured on the 'Varta' marked lipos:

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You will note that from warning at 3.2 V to switch-off at 3.1 V only takes a minute or less... It crapped out once this week (am not always around to see warnings). Don't remember the discharge current.

Now that you mention this I will try in a test-setup at a modest current (maybe 1 A) how long these new ones last. I like your big heatsink with fan battery test setup.

The difference at the peak is only about 20/28 or 71%...

Yes I have something like that from the local RC shop for my laser RC plane:

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used it to jump start my scooter :-)

Yes, well I meant the fuse for accidently shorting it.

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Jan Panteltje

Possibly (probably) fake.

I replaced the Varta NiCd cells in a car instrument cluster a few years ago- they lasted more than 20 years!

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Here's another way of doing it. Charge the battery to some voltage below 4.2v and see how much capacity it has left: Presumably, when it's done charging, the terminal voltage will equal the charging voltage. At your 3.1v cutoff, the % of rated charge is zero. 10% looks to be about 3.75V.

For LiFePO4 cells, 10% is about 3.25V.

Incidentally, notice how many charges he gets if you charges to something less the 100% of capacity.

As I understand it, when the discharge curve hits the knee and starts to drop off rapidly, it's time to stop charging.

Don't forget the battery terminal clamp. I was getting really erratic results when I was using a battery holder like this: Use the force.

The heat sink and fan are necessary. I accidentally dumped some loose junk over the fan, which then stopped. About 30 mins later, I smelled smoke.

If you plan to build your own, please note that the CBA II has a design defect in that it measures the battery voltage at the wrong end of the test leads. At high currents, the voltage drop through the leads and battery contacts can be substantial. I wanted to move the sense wires from inside the device to the battery terminals, but never finished.

For my test, I used 1.3A because that's what the flashlight I was testing draws at maximum brightness. I would expect your counterfeit cells to look very much like my counterfeit test battery:

You might want to measure how long it will take your fuse to blow with a partly discharged battery and a not so perfect short, such as a screwdriver. A fully charged battery and a good short circuit will blow most any fuse or fusible link. However, that's not always the case when it shorts. I've had the fuse do nothing while the wiring got hot enough to melt the insulation. Fusible links:

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Jeff Liebermann     jeffl@cruzio.com 
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On a sunny day (Sat, 21 Nov 2015 14:25:34 -0800) it happened Jeff Liebermann wrote in :

I have only one lifepo4 cell so far, like this, but different seller):

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it is in a keyboard, I only charged it once.. IIRC in May 2014, it is still working..

I do see prices are now coming down for lifepo4.

Right, and do not use Chinese Alligator test leads, the copper wire in those is so thin that at 100 mA it drops up to 2 V for a 50 cm lead! This has gotten me several times, finally keeping the alligator clips and soldering real wires on it. Were not even soldered, just sort of pressed against the metal.

Ehh I should have read ahead!

Or make your own electronic over current switch, depends on how much you trust your own designs... :-) But I think to fuse a 25 A capable lipo battery with a 1 A fast fuse is OK for what I do.

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Jan Panteltje

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