69 lines
3.1 KiB
Markdown
69 lines
3.1 KiB
Markdown
# Battery discharge curves
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I wanted to buy some Sony VTC6 batteries, and I was wary of fakes, so I wrote a [battery discharge calculator](https://gitlab.com/stavros/assault-and-battery/) with an associated hardware component (just a simple current and voltage sensor). I then took some measurements of my known-good batteries, and the new ones I bought.
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The methodology was the following: I connected the battery to the sensor, and the sensor to a configurable load. I set the load to draw a certain amount of amps until it reached a cutoff voltage, and then to stop. I then plotted mAh drawn versus voltage, as well as amps drawn.
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The batteries I connected were in various states of use, and various configurations (for various reasons, I couldn't test single cells). The configuration, state of the battery and provenance are mentioned below.
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Here are the graphs:
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## Genuine Sony VTC6
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This is a genuine (as far as I can tell) Sony VTC6, fairly used in high amp draw situations (I use it in my plane), in a 3S configuration:
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You can see that it output around 2600 mAh before I stopped it at 3V, which is quite good.
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Here's a brand new genuine VTC6, again in a 3S configuration:
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This time I ran it all the way down to 2.8, and you can see it output the full 3000 mAh.
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## Fake Sony VTC6
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This is a pretty blatantly fake "Sony VTC6", brand new, in a 2S configuration:
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The performance falls off a cliff after around 3.6V, and it only outputs 1600 mAh before it dies completely.
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Trying to draw 6-7A is even more spectacular (and it gets very hot to the touch):
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Notice the huge voltage sag right as the load starts drawing.
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## Reclaimed NKON VTC-6
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I bought some [reclaimed Sony VTC-6 from NKON.nl](https://www.nkon.nl/sony-us18650-vtc6-reclaimed.html), and I tested them here, in a 2S configuration at 1.5A.
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They seem to be very genuine:
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Not only are they genuine, but if we compare with the graph of the brand new VTC-6 above, we see that the reclaimed NKON batteries have had zero (or very few) cycles, as they gave the same Ah at 3.3V/cell as the new ones.
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If you need it, here is the [raw Assault and Battery results CSV](/resources/29e39ead4d104c2c8133b028882b6a98.csv) for this battery.
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## White CNHL 4S 4000 mAh
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This is a white CNHL 4S 4000 mAh LiPo battery, slightly used:
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You can see that it's pretty decent, outputting nearly all of its nominal mAh, decently linearly, with a slightly faster drop after 3.7 V.
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* * *
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<p style="font-size:80%; font-style: italic">
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Last updated on December 19, 2022. For any questions/feedback,
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email me at <a href="mailto:hi@stavros.io">hi@stavros.io</a>.
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</p>
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