Bench Retest Results: Molicel P30B - 30A 3000mAh 18650
- By JayEmm
- Batteries and Chargers
- 12 Replies
Thanks @Mooch for pinging me back, and sorry for the delay in coming up with my report. Here it is:
0) Paired them in 2S configuration and put them into a Rekon35 drone, safely zip-tied to a couple of heavy bricks (so I could push throttle to the max and maximize current draw without having the drone going up to the moon):
In the state they came in (around 4.07-4.09V per cell, as I reported previously), the first pair managed to supply 1809mAh at an average current of 10.9A over a 588 seconds interval, starting at 4.07V and ending at 3.00V per cell, according to the drone's telemetry (I haven't calibrated its current/voltage sensors, but the values seem to be reasonable to me). Another pair started at 3.85V per cell (I did some previous testing with them) and ended at 2.45V per cell and was able to supply 1688mAh over the course of 536 seconds, with an average current drawn of 11.2A. Given the batteries started at an unknown charge state, these are highly caricatural results, will try and obtain more reliable ones after step 1 below is over.
I repeated those tests with the same batteries after putting them through the 5x D>C cycles on the MC3000 (see below) and here are the results (first frame of the OSD display from the drone when each battery pair reached 5.0V total, ie 2.5V per battery):
Pair #1 (batteries i and ii):
Pair #2 (batteries iii and iv):
So, according to the drone's voltage/current sensors, these batteries (after being fully charged to 4.2V with 60mAh residual current) were able to produce respectively 2562mAh and 2573mAh when drained all the way down to 2.5V at ~10A (current varied by half-an-amp up and down as the drone's FC did its thing, but I was able to keep an average very very close to 10A).
This is a significantly (~10%) less than the over-2750mAh at the same 10A we can interpolate from the 10A discharge graph you posted in this topic's OP.
The good news is that, even after being discharged at ~10A for almost 15 minutes straight, the batteries did not heat up too much: an IR thermometer clocked them at just 38C and the time-honored touch-with-finger test showed them only mildly warm, so it seems they should at least be safe to use.
The capacities didn't improve much if at all, they remained at around 2800mAh capacity, and this while being discharged at only 1A, while they should be producing at least 3000mAh. So also about ~10% capacity loss, which aligns with was seen with the 10A discharges on the anchored-drone test.
To sum it up, on my advice with these results, my friend opened a dispute on his AE purchase and managed to negotiate a partial refund which brought his cost down to the equivalent of USD 2.24 per battery, which I think is a fair price, and will be using them in their reduced capacity, given that they should at least be safe to use at 10A due to not heating too much.
I checked that the voltage the MC3000 displayed was the same as the one shown by my UNI-T UT210E DMM, and indeed it was exactly the same. Did not check the current as that would be far more involved (given the UT210 can only measure current using its clamp, measuring it would have meant placing a longer wire somewhere along the discharge path, and as a way to do that was not obvious and I had neither the inclination nor the time for such an endeavor, and given the voltage sensor was right on the money, I decided to just believe the current sensor was also accurate.
Now my friend managed to locally procure a couple of Murata VTC6 batteries that were imported by soneone else from NKON.NL and I'm now trying to help him test them. And I have questions about these batteries too... will be be posting them on the VTC6 thread.
EDIT: the VTC6 threads (both test and retest) are closed for comments, so I opened a new one: Murata VTC6, how to charge? Anyone that can, please help!
Thank again @Mooch for everything!
