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+++ title = "Battery discharge curves" weight = 1 sort_by = "weight" insert_anchor_links = "right" +++ I wanted to buy some Sony VTC6 batteries, and I was wary of fakes, so I wrote a battery discharge calculator 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.
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.
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.
Here are the graphs:
Genuine Sony VTC6
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:
You can see that it output around 2600 mAh before I stopped it at 3V, which is quite good.
Fake Sony VTC6
This is a pretty blatantly fake "Sony VTC6", brand new, in a 2S configuration:
The performance falls off a cliff after around 3.6V, and it only outputs 1600 mAh before it dies completely.
Trying to draw 6-7A is even more spectacular (and it gets very hot to the touch):
Notice the huge voltage sag right as the load starts drawing.
Last updated on September 09, 2021. For any questions/feedback, email me at hi@stavros.io.