Nitecore F4 Powerbank Charger Review

The Nitecore F4 is a four-bay charger that doubles as a powerbank. It’s a useful travel device which can have a high capacity, too! Read on!

EDIT: One-year update.  I used this a bunch, and for a while.  Then it sat in a drawer with 4 of my favorite cells.  I clicked it to see how it was charged and… nothing.  I then charged it overnight and … nothing.  Pulled out the cells and tested them – all four of them are 1.42V.  That’s essentially dead, though they might take a charge once they’ve rebounded (I don’t really recommend this!).  

So if you’re going to use this frequently, it’s fine.  If you’re going to not use it for a while take the cells out.  The standby drain is not insignificant, and there is apparently no low voltage protection.  

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Official Specs and Features

Here’s a link to the Nitecore F4 Powerbank Charger product page.

Price

This is going for $28.95 at Illumn.com right now.

Short Review

This is now my go-to powerbank.  I like the 4-cell capacity, the springs feel rugged, and the UI is intuitive and honestly, not needed all that much.  Two output ports is a bonus.

Long Review

Key Features

• Four-slot flexible power bank
• Charging and discharging functions
• Integrated intelligent USB charging and discharging management system
• Capable of charging 4 batteries simultaneously and controlling each slot independently
• Micro-USB 2.0 input port enabling 1A charging for 2 slots simultaneously
• 2 USB output ports capable of outputting 2A current simultaneously
• LCD real-time display on Battery Voltage, Charging Current, Charged Capacity, USB Output Current and Output Capacity
• Energy saving hibernaion function for LCD display
• Over-discharged battery activation
• Reverse polarity protection and anti-short circuit protection
• Designed for optimal heat dissipation

Manual and Packaging

Typical Nitecore packaging here.

Below is the manual.  Also typical Nitecore.  No complaints about the manual or packaging!

What’s Included

• Nitecore F4 Powerbank/Charger
• Charge cable (USB to micro-USB)
• Manual and paperwork

Build Quality and Durability

As a charger, the build quality of this charger is typical.  It’s purpose built-in that it only works with 18650 cells, so some design changes can reflect that – it has big thick springs instead of slides.  These springs allow the connection of any type 18650, but only 18650.

There’s a cover for the charger, which makes sense since it’s a powerbank too, and will likely be used on the road.  The cover is frustrating if you change cells often.  If you never intend to change the cells once they’re installed (ie, if you plan to use this mainly as a powerbank, then don’t sweat the cover.  More on the cover.

The top has a big clicky power button, two USB ports for discharge (aka USB-Out), and one micro-USB, which is used for powering the F4 as a charger.  The bottom just has some molded in branding and regulatory stuff that keeps us safe.

These springs are spectacular.  Beefy enough to hold cells in place, but allow the use of long protected button top 18650 cells, or unprotected flat top cells.

The springs connect to the negative end of the cells, and there’s a diagram in each bay to demonstrate that.

The top is hard to remove with just fingers.  There isn’t much purchase, and it’s really generally disinclined to be removed.  But it doesn’t resist in a … ‘breaky’ way.

The cover is indexed too, so it’ll only install correctly in exactly one orientation.

The window which shows the LCD screens is open – no glass or cover etc.  That (and other design aspects, too) does mean that the powerbank is not the least bit waterproof.

This grip does nothing whatsoever.

Each bay has its own battery capacity symbol, but the display cycles the top area (voltage/mAh, etc) for each bay, per click.

Here’s the nib on the cover that makes it specifically indexed.

Size

Dimensions: 113.4mm×86.1mm×27mm
Weight: 122.5g

It’s probably not the smallest 4×18650 powerbank.

Power

Power is provided to the F4 via an included USB to micro-USB cable.  The port is at the top of the device, sharing space with a power button and two USB ports.

As a charger (and as stated) the F4 can only power 18650 cells, but it can power any sized 18650 cells.  I have a sampling below (including two of my longest cells, and some actual 18x65mm cells.

See how much that EVVA cell compresses the spring – it works fine this way, of course, and that springiness allows all these sizes to operate fine.

Pushing the power button while the cells are installed cycles which bay is being displayed (among other actions; more on that later).  The display shows which bay is active by saying the slot number over the active bay.  Whichever slot is selected, that cell’s info is displayed at the top of the display.  This is uncomplicated in practice.

 

I tested the charger as best I could.  One, two, three, and 4 cells being charged, with Bay 1 being logged in every case.  The cells charge at 1A or thereabouts except in one test.  But generally it seems that every bay charges at 1A no matter what else is present.  That’s contrary to the manual which says the charger does 0.5Ax4.

And what’s more, the time of the test supports that.  It’s unclear what is happening in this case.  Since the F4 is powered by a lowly 2.4A USB power supply, it can’t be charging at 4A total.  In any case, charging is sufficient.

The F4 also has power out (of course, it’s a powerbank).  Here’s a short test, pulling up to ~2.1A out of one port.  The F4 does that easily.  This test stopped short because I was testing what happens when cells are swapped while the USB out is active.  Turns out sometimes the output is seamless, but sometimes it resets.

But I was curious what the F4 does for longer discharges, too.  Below is the discharge of a single cell for the capacity of that cell, at 2.1A.  There was some discussion that the F4 doesn’t have LVP.  It does, but what it does seem to have is a willingness to let you kill your cell.  If you continually restart USB-out even with a depleted cell, the F4 seems to let you draw power out of it.  But left to its own devices, it’ll stop when the cell can no longer output the desired amperage without a significant voltage drop (below around 2.8-2.9V in my experience.)

I don’t have two USB loads, but I’d be interested if this can output 2A from each, simultaneously.  Nitecore says they can.  So much so in fact that they say protected batteries can trip under this load.

User Interface and Operation

There’s a single e-switch on the F4.  It’s a big power button, and it’s on the top.

Short pressing the button will cycle information for each bay, provided a cell is in that bay.  This display has a backlight too and turns on when buttons are pushed.  It doesn’t stay on long though, so won’t be distracting in a dark room.

During charging of cells in the bays, the screen displays Battery Voltage, Charge Current, and Charge Volume (aka “mAh”).  When full, the bay will indicate so with “End,” and the battery icon for that bay will be steady (not blinking.)

During the powerbank function, clicking button still cycles through the bays.  But the display does something different – it shows Battery Voltage, Output Current, Output Volume (mAh), Battery Leve, and the USB icon.  That’s “USB 1″ or USB 2”, for whichever port is active.

Interestingly the F4 seems to discharge from bays 1 and 2, then 3 and 4.  This is so that if you wish to pull a cell for use in a flashlight, the cells won’t have been depleted by the discharge function.  But ultimately, of course, the F4 switches to whatever bay is needed for powering the USB ports.

Just as a fun annotation here… The F4 does attempt to “charge itself” – using the included charge cable and going from a USB port to the micro-USB port, does seem to redistribute the power that’s available in what cells are in place.  Obviously, this isn’t the pathway to unlimited power, but I’m surprised Nitecore didn’t prevent the unit from even seeming like it’s going to do something in this setup.

Conclusion

What I like

• Dual USB out ports
• UI is uncomplicated
• Powerbank but with the ability to supply and swap cells

What I don’t like

• Could be USB-C
• A little waterproofness would be a nice touch
• Cover is fiddly

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Notes

• This item was provided by Illumn.com for review.  I was not paid to write this review.
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