With this NP-BX1 battery test fixture in hand:
The discharge tests run at 250 mA, which is probably a bit low, as the HDR-AS30V camera can capture video for about two hours on a single battery. Given the Sony’s nominal 1.24 A·h (love that precision!) capacity and derating the Wasabi’s ambitious 1.6 A·h, two hours suggests a current around 500 mA would be more appropriate, but we’ll go with a lower current for now.
Oddly, the two Wasabi batteries (green & blue traces) outperform the Sony OEM battery (red and purple) in terms of voltage:
I can’t explain the small kink just before the big dropoff for both Wasabi batteries. Perhaps the protection circuitry behind the battery terminals has a slight peculiarity?
Looking at the total energy delivered, however:
The Sony battery says it’ll deliver 4.5 W·h and actually produces 4.8 W·h. The Wasabi batteries claim 5.7 W·h and don’t even come close at 4.25 W·h.
I cross-checked those results by importing the CSV data into a spreadsheet, computing the point-by-point power, finding the average, and then multiplying by the total test time in hours. Doing it a couple different ways says you can eyeball a reasonable value by multiplying the median voltage by the test current to get average wattage, then multiplying by the total test time to get W·h. That’s within a few percent, which is good enough for me.
The camera’s power supply undoubtedly has a low-voltage cutoff, but it’s a single-cell battery and they might just run it down around 2.8 V; in that case, the Sony batteries will last longer. If the voltage cutout is 3.5 V, similar to the Canon camera, then the Wasabi batteries win.
I don’t have enough experience with the camera or the batteries to predict anything based on actual use.
3 thoughts on “NP-BX1 Lithium-ion Batteries: Sony vs. Wasabi”
For no good reason this reminds me of the time I had to calculate the stored energy in a pair of two-liter 4500psi carbon fibre air tanks. And then convince NASA that they should let me put the literally the energy of a stick of dynamite onboard their shiny new airplane… not to mention the enormous (4AH @ 24VDC if I recall) handmade lithium batteries right next to it…
Did they make you do the Rickover thing: sit next to your hardware during the first flight? [grin]
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