got a disappointing 2:15 of run time first try with 2200 mAH dracast (6ch phantom). 2:12 on second test
does not compute as i get over 3 hours from 2500 mAH NiMH at 5V (confirmed since with different batteries)
notice that Voltronic's 6600 mAh test was 5 times the capacity of the 2200 mAh test. Assuming the battery isnt defective it would have to be premature voltage cutoff by the zoom
apparently under high load the voltage sag on the 2-cell battery trips the relatively high voltage cutoff of the zoom (around 7.0V) much earlier than the 6-cell 6600 mAh (where we would expect something slightly over 3X capacity vs the 2200 mAh battery, perhaps 3.5X, but not 5X! best guess on the NP-F discharge rate, based on a proper 3.0V cutoff, would be close to 0.3C. the 6 cell 6600 mAh would be well under 0.1C, probably closer to 0.05C with a proper 3.0V cutoff. look at the graph below how much juice is left in the battery below 3.5V/cell, close to 40%! Most other manufacturers spec 3.0V as cutoff in their devices, which is still high enough to not damage the battery. a deep discharge would be something like 2.7V which some devices do. remember that cutting off at 3.0V *under load* is still leaving a safe amount of juice in the cell as not to damage it.
submitted this to support today:
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i did come across some bugs in 1.20 firmware, and some suggestions for future firmware
bug: sometimes tracks dont arm despite the knobs being clicked on... a reboot corrects it
bug:display power saving acts erratically sometimes. where normally it goes dark after 30 seconds, sometimes it will just stay on. ive also seen it randomly click on and off by itself while recording. last night when it was stuck on, it flashed off for a second then back on (and stayed on). it was right when displayed NPF battery voltage was flipping from 7.2 to 7.1V, not sure if that is related in any way
suggestion: make an option for screen timeout in menu. something like 30 sec/60 sec/5 min/never
suggestion: make order of power sources used in menu selectable if possible (even if its just selecting between NPF and AA))
suggestion: allow user adjustable cut off-voltage when using NPF battery, as of now it cuts off at about 7.0V (3.5V/cell), which leaves upwards of 40% of the battery unused with smaller batteries like 2200 mAh used in high-drain situations like 6-channel w/phantom power. (between 0.3 and 0.5C, indicated by blue oval on graph below). Having this cutoff adjustable down to 6V (3V per cell) would offer extended runtime and is more on par with other devices. These batteries are cheap, lost takes are not!-----------------------------------------------------
its difficult to estimate state of charge of a resting li-ion cell by simple voltage since the curve is so flat. after cutting off, resting voltage after 10 mins or so is 7.6V (3.8V per cell... which seems like theres a lot of juice left in there...)
in fact i can take the 'dead' battery (7.0V cutoff from 6-ch phantom), and boot up the zoom in lowest power case i can imagine (1 channel no phantom), it displays 7.4V under load and runs for 40 more minutes before cutoff (woulda been probably an 1.5hr+ to 3.0V/cell cutoff.. but anyway)
i would venture to guess i could do the same with "dead" AAs. drop down from 6 to 2 channels and eek out some more runtime... good in a pinch
depending on cutoff voltage of this device, it might be able to be used to squeak the rest of the power out of the NPF battery and into the USB-C port
https://www.amazon.com/Power-Junkie-NP-F-Blind-Spot/dp/B07NF14XW4in any case, for now, absent a firmware update, smaller NPF cells like 2200 mAh are a poor match for high-drain recording such as multichannel w/phantom. 4400, 6600 or larger would get well over 2-3X the usable capacity
im in the process of doing a runtime test with just 2 ch phantom, which is a better fit for this battery
Time 0 = 7.9V
20 mins -> drop to 7.8V
1.5 hrs -> 7.7V
2.25 hrs -> 7.6V
2.9 hrs -> 7.5V
3.9 hrs -> 7.4V
4.1 hrs -> 7.3V
4.3 hrs -> 7.2V
4.5 hrs -> 7.1V
4.7ish hrs ->switched over to internal AAs
idle battery voltage after this test was right around the 7.0V cutoff, so there was much less voltage sag at this <0.2C test
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TLDR: i orderd a 4400 mAh battery. About the same price and should give about 3X the runtime of the 2200 mAh due to high cutoff voltage