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10ah 18650 cells

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tooki:

--- Quote from: bastl_r on May 08, 2024, 05:35:16 pm ---Hi
Buy from nkon.nl if you can.
Always good stuff. No crap.

--- End quote ---
A good EU source for genuine lithium ion cells is Reichelt, based in Germany.

Refrigerator:
Not to brag but I've actually held a genuine Ultrafire battery in my hands.
Yes it had the protection board and yes it had the rated capacity.
A true rarity, i'm sure, just like the TowerPro MG995 was back in the day.

pcprogrammer:

--- Quote from: Kean on April 28, 2024, 11:42:43 am ---I bought 48 pcs of HG2 18650 from an AliExpress seller that were specified for 3000mAh down to 2.5V.
I've only been test discharging them so far at 1A to 3.0V, and have been getting pretty consistent readings of 1800mAh.

So not great, but certainly not as bad as some reports I've seen - and for the price I paid compared to local trustworthy suppliers I am happy.
I will be assembling these into packs that go inside some 12V SLA shells for backup power application.

--- End quote ---

What spread in parameters can one expect when ordering a batch of the more reputable 18650 batteries from one of the places mentioned here? For instance these: https://www.nkon.nl/fr/sony-us18650vtc4-flat-top.html

I understood that for assembling a battery pack it is important to match not only the capacity, but also the internal resistance and for this I wonder how many batteries one would need to get to get 20 matching batteries. The pack I need them for is made up of two cells in parallel and 10 of these in series.

I also read that for a string in series the capacities need to match as much as possible, but for parallel this does not matter that much. Is this true?

AVGresponding:

--- Quote from: pcprogrammer on July 24, 2024, 05:36:12 am ---
--- Quote from: Kean on April 28, 2024, 11:42:43 am ---I bought 48 pcs of HG2 18650 from an AliExpress seller that were specified for 3000mAh down to 2.5V.
I've only been test discharging them so far at 1A to 3.0V, and have been getting pretty consistent readings of 1800mAh.

So not great, but certainly not as bad as some reports I've seen - and for the price I paid compared to local trustworthy suppliers I am happy.
I will be assembling these into packs that go inside some 12V SLA shells for backup power application.

--- End quote ---

What spread in parameters can one expect when ordering a batch of the more reputable 18650 batteries from one of the places mentioned here? For instance these: https://www.nkon.nl/fr/sony-us18650vtc4-flat-top.html

I understood that for assembling a battery pack it is important to match not only the capacity, but also the internal resistance and for this I wonder how many batteries one would need to get to get 20 matching batteries. The pack I need them for is made up of two cells in parallel and 10 of these in series.

I also read that for a string in series the capacities need to match as much as possible, but for parallel this does not matter that much. Is this true?

--- End quote ---

Kind of, but bear in mind that if the capacities are very different, you need to limit the charge current to a friendly level for the lowest capacity cell

pcprogrammer:

--- Quote from: AVGresponding on July 24, 2024, 04:33:16 pm ---Kind of, but bear in mind that if the capacities are very different, you need to limit the charge current to a friendly level for the lowest capacity cell

--- End quote ---

I read that too. This is just to make sure that if the other cell(s) go bust the charge current won't be to high to ruin the remaining cell.

It is an interesting subject with the necessary pitfalls and you can't just go on what is on the internet. Someone told me that Liitokala batteries are reasonably good as long as you buy them from a reputable store. Bought six from here: https://nl.aliexpress.com/item/32805750680.html but they seem to be fake or at least reclaimed. Capacities are no where near the VTC4 specifications.  :palm:

I got into this because an original Husqvarna battery pack is very expensive and with only two dead cells, repairing should be way cheaper, but with all the stuff I bought for playing with Liion cells a new pack would not have been that more expensive.  :-DD

Got a battery spot welder, an Atorch DL24 150W electronic load, two Liitokala chargers (Lii-500 and Lii-M4S), a YT1035+ resistance meter, two four wire battery holders and a bunch of other battery related stuff. But that is always handy for other projects.  8)

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