Lesson Learnt: Use quality battery with BMPCC 4K
Posted: Tue Jan 15, 2019 10:17 amI noticed a significant rate of battery drain on my F970 batteries that came with Aputure lights (7200mAh rated, and I thought they would be just fine) when powering the Pocket 4K, so much so that I can merely get 1 hour of run-time.
So I bought a custom-made F990 (8 x Panasonic NCR18650b cells, 2s, 13600mAh rated) and a dummy load to test the discharge. And here are the discharge curves and tested capacity under a constant 4A current draw and cut-off at 5V (if a Canon LP-E6 lasts half an hour, then probably 4A is a good guess for worst-case) with similar ambient conditions.
Above is the discharge curve of Aputure F970 which lasted 54.5 mins. 3623mAh tested, 50.3% of the claimed capacity. When the current is cut, the voltage of the battery slowly returns to around 7.4v again, but it drains immediately empty again under 4A load.
Above is that of the custom-made F990 which lasted 198.5mins. 13240mAh tested, 97.4% of the claimed capacity.
But I haven't tested the battery on camera yet, it takes ages to recharge. I don't know if the camera voltage read-out is flawed or not because I've been suspecting that it might be inaccurate since I measured different voltages with a multi-metre from in-camera read-out.
I guess the same is happening for those third-party LP-E6 batteries that doesn't last - the cells just cannot handle the massive current draw and they drop voltage so rapidly that at the end of the discharge curve the voltage just plummet - and the camera just shut off without warning. At least this can be one of the contributing factors.
(Not paid by Panasonic to say their battery cells are good)
So I bought a custom-made F990 (8 x Panasonic NCR18650b cells, 2s, 13600mAh rated) and a dummy load to test the discharge. And here are the discharge curves and tested capacity under a constant 4A current draw and cut-off at 5V (if a Canon LP-E6 lasts half an hour, then probably 4A is a good guess for worst-case) with similar ambient conditions.
- Screenshot (7).png (242.6 KiB) Viewed 737 times
Above is the discharge curve of Aputure F970 which lasted 54.5 mins. 3623mAh tested, 50.3% of the claimed capacity. When the current is cut, the voltage of the battery slowly returns to around 7.4v again, but it drains immediately empty again under 4A load.
- Screenshot (6).png (250.53 KiB) Viewed 737 times
Above is that of the custom-made F990 which lasted 198.5mins. 13240mAh tested, 97.4% of the claimed capacity.
But I haven't tested the battery on camera yet, it takes ages to recharge. I don't know if the camera voltage read-out is flawed or not because I've been suspecting that it might be inaccurate since I measured different voltages with a multi-metre from in-camera read-out.
I guess the same is happening for those third-party LP-E6 batteries that doesn't last - the cells just cannot handle the massive current draw and they drop voltage so rapidly that at the end of the discharge curve the voltage just plummet - and the camera just shut off without warning. At least this can be one of the contributing factors.
(Not paid by Panasonic to say their battery cells are good)