CHEAP NEW ORIGINAL 18650 21700 BATTERY CELLS, POUCHES AND PACKS

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Quick testimonial 3:

I've also received my cells. Everything is OK.
Today I'm going to do a discharge test with 2.5, 5, 7.5 and 10A.
I can make a graph of discharge and attach it here.
 
I tested quickely on my bike with 4p 20s, big sag above 50 but it is perfectely normal for those cells. Still push well ;) will test capacity later with lower C
 
with only 4p i wouldnt be expecting anything different :D but i spose that was just for testing perposes?

im waiting for some 200cells in the post right now, id be using atleast 10p id say, that way they wouldnt get such a thrashing and perhaps last a bit longer...

btw.sorry, is that 50A load you speak of, or kph?
 
I made a few discharge tests with small discharge currents.
Start battery voltage: 4,2V
End of discharge: 3,0V

Here are the results:

29axkbl.png


For a few days I will do tests with higher discharge current.
 
Discharge test with higher discharge current.

Start battery voltage: 4,2V
End of discharge: 3,0V

Here are the results:

dexqvs.png
 
grrga said:
I made a few discharge tests with small discharge currents.
Start battery voltage: 4,2V
End of discharge: 3,0V
Click to expand...

Very interesting data. The cell is not on dampfakkus and lygte-info - just the LG MH1.

Some points and questions:
More informative would perhaps be a stop at 2.7V or 2.5V (usual: "“Standard Discharge” shall consist of discharging at a constant current of 570mA to 2.5V." )
At 3.0V the curves are still rather flat! Particularly with higher currents you do not see the real content so.
The LG MG1 / MH1 as most NCA/NMC cells do not (as LG D1 or UR-FM or LiPo's ; click) have that flat curves, which fall off sharply below 3.1V . They are designed for 2.7V typical BMS undervoltage stop.

The vertical distances (->"voltage sag") between the curves look rather irregularly spaced, though constant current steps of 1A or 0.5A . Is that really due to cell properties? How defined and how constant is the charge stop condition? What is the charge stop temperature about? (Temperature affects most the state-of-charge a voltage X, current Y).
Is the meter somehow calibrated against multiple multimeters or so - regarding current and voltage?
Is it a 4-point measurement, or are the resistance of the cables/holder/contacts subtracted? or how are the resistances of cables/holder/contacts?

Are the curves made with one and the same cell? starting from the very first cell cycle? Or did you do some 5 formation cycles before? The seemingly very first discharge @ 0.5A still shows that kind of out-of-factory memory effect - a complex shape below 3.6V storage voltage. At the beginning the capacity and the curve form may still change a lot - thus same formation cycles are good before doing comparative voltage sag measurements - and a repetition of the first discharge later or so to check for effects.

Most interesting would be if sb could do some cycling tests finally - like this. But thats a lot of effort ... Measuring at ~ M/3 perhaps is good for testing cycle life - and is near to typical EV currents not too aggressive. M = max charge/discharge rating = 2.9A / 10A for LG MG1. Thus at 1A charge and 3A discharge.
 
Graph of discharge Panasonic's cells:

 
i'm interested in using them for a skateboard. Can you simply string any of these together to make 30volts and 5ah or is there more complications necessary? I know how to string my simple HK 2 cell packs together but I'd be stringing many more together to get the same pack. Is there a tutorial on how to make a pack? Or materials people use?
 
http://endless-sphere.com/forums/viewtopic.php?f=14&t=26383#p381104
there might be some useful stuff here..
 
Hummina Shadeeba said:
i'm interested in using them for a skateboard. Can you simply string any of these together to make 30volts and 5ah or is there more complications necessary? I know how to string my simple HK 2 cell packs together but I'd be stringing many more together to get the same pack. Is there a tutorial on how to make a pack? Or materials people use?
Click to expand...

Of course you can! There are many topics on how people connected them.

https://www.endless-sphere.com/forums/viewtopic.php?p=712156&display_history=true#p732917
 
recycling some old laptops sounds great but I'm thinking it'd be hard to find the higher c rating id want on a skateboard with a 6 or 5ah and 30volt pack.

are these batteries safer than typical HK lipo batteries?

I want to get IMR batteries and I think I'll need around 20c for a skateboard. If I charge them all in parallel will I need to use balance leads? Will I need a BMS or the safer cells that have a fuse? I imagine not.
 
High rate batteries don't have internal fuse. You can use bms or balancing charger with some kind of low voltage alarm. They are almost 100% safe.
Used laptop cells are around 0.2C rate, so don't even think of them, you need new, high c rate cells, one of those which I listed previously.

If you have 30V pack, which is 8S, you wont be paralleling them each time you charge, so you'll need balancing wires. They will probably stay in balance, but if you discharge them deeply, you should monitor them carefully and balance them before first use.

What current do you need from your pack?
 
I received my battery. The packaging is very well done. Transportation was quick to belgium. The cells are well balanced to 3.6V, I had to redo only two welds.
I am very happy :D

thanks
 
riba2233 said:
High rate batteries don't have internal fuse. You can use bms or balancing charger with some kind of low voltage alarm. They are almost 100% safe.
Used laptop cells are around 0.2C rate, so don't even think of them, you need new, high c rate cells, one of those which I listed previously.

If you have 30V pack, which is 8S, you wont be paralleling them each time you charge, so you'll need balancing wires. They will probably stay in balance, but if you discharge them deeply, you should monitor them carefully and balance them before first use.

What current do you need from your pack?
Click to expand...

60amps current maybe
But will i need to add balancing wires to every battery including those in series?
 
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