The F6 is very versatile on the battery front: it can be powered from 4 AA cells which sit in a caddy inside the recorder; or an L-series battery which clips on the back; or via the USB-C port. This gives you a great range of options, but of course it's worth knowing how much run time you get from each of these options.
You can use alkaline (non-rechargeable) batteries in the F6, and that's worth knowing if you find yourself in the back of beyond and out of power; but most of the time NiMH batteries are the way to go. These are a little pricey, but of course rechargeable, and can last a long time; see below for my test of batteries I've been using quite heavily for 4 years.
The AA batteries go into the F6 in a caddy which fits into a port in the bottom of the machine. You would have to take it off a tripod plate to open this door, which is a pain. But with such a small machine, compromises clearly had to be made.
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The bottom, showing the AA battery port. |
The AA battery port, showing the caddy and batteries installed. |
Sony L-Series batteries are very widely used in video. Although originally for larger video cameras, they have become common on accessories such as lights, camera monitors, and so on — including some audio recorders, such as the F6. They are made by lots of different companies, which makes them cheap. These should all work on the F6, but quality and true capacity can vary.
L-series batteries slot on to the rear of the F6, and stick out the back. These batteries come in 3 sizes, all with "NP-F" designations: NP-F 550 are thin and low capacity; then there's NP-F 750 or 770; and then 950 or 970. The difference between the "50" and "70" versions is down to slightly different cells, or something. It affects capacity, so check the battery's rated capacity.
The stick-out will be about your battery's height minus 8mm. The NP-F770 size is good for the F6, and fits nicely in the K-Tek bag (and in my DIY bag).
Note that the battery name must be "NP-F" followed by digits. Batteries such as "NP-FV", "NP-FH", "NP-FP", etc., are completely different and won't work.
It's all very well waffling about what kinds of batteries I like, but there's nothing like actual data. So I decided to run some tests. My idea was to check a number of things at once:
All tests except the last in the table were run with two MKH 8040s on channel 1 & 2, with phantom power enabled, all other channels turned off. The final test was run with JRF contact mics, instead of the MKH 8040s, and phantom power was OFF. Otherwise all was the same. (Contact mics because those are the mics I have that don't use phantom power.)
In all cases I checked that the machine was actually recording sound (TV sound etc). Record mode was 32-bit float, and the display was mostly blacked out. All batteries were freshly charged before testing, including the brand new ones.
The results:
| Type | Make | Bought | Condition | Mics | Phantom | Run Time |
|---|---|---|---|---|---|---|
| AA | Eneloop | Jan 2016 | well used | 2x MKH 8040 | YES | 4h 53m |
| L-series NP-F970 | Pixel | Jan 2020 | lightly used | 2x MKH 8040 | YES | 31h 06m |
| L-series NP-F770 | DSTE | Apr 2020 | brand new | 2x MKH 8040 | YES | 19h 15m |
| AA | Eneloop Pro | Apr 2020 | brand new | 2x MKH 8040 | YES | 6h 48m |
| AA | Eneloop Pro | Apr 2020 | brand new | 2x JRF contact | NO | 11h 15m |
These results seem pretty solid to me; contrary to some opinions I've seen, the F6 seems to perform well on AAs, at least for a reasonable-length recording session. I wouldn't have any problem running my F6 on AA batteries, at least for stereo — even running Phantom power (which I usually do), even with standard Eneloops, even my 4-year-old ones. I would want to have spares, of course.
For longer sessions, like a drop-and-recover overnight, L-series looks to be the job. I just can't see battery life being an issue with these. If it is, then you've always got USB, which gives you whatever capacity you can buy; but of course this means carrying around a second device and a cable. With an L-series battery installed the machine feels like a solid piece of hardware, even though its depth is increased.
I am surprised by the phantom power test; the mics only use 3.3 mA, which is about 33mA at battery voltage, so it's strange that it makes so much difference. I know, people have been saying for years that phantom eats your batteries, but I've never completely believed it: modern voltage converters are extremely efficient, so I can't see any excuse for this.
