Nitecore F1 stops charging at 4.08v! Defective?

INPUT
DC 5V, ≥500mA

OUTPUT
4.2V±1% (slot)/5V±5% (USB), 1000mA MAX (slot)/1000mA (USB)

http://charger.nitecore.com/product/f1

Do your MATH !

Input is 5v @ 500mA
That is 2.5watts to play with … So charge current is very dependent on the state of the battery ……
So the battery voltage determines charge rate ( Remember we have 2.5watts to play with )
So Watts to Amps (A) conversion calculator
Do some math …

Amps = Watts devided by Volts

So we have 2.5 of those watts , divide it by Voltage and you should be left with charge current less any losses inherent in the charger …

( Again don’t forget those nasty variables )

I believe Nitecore says input ≥500mA because the charger can still charge at a reduced rate if you only give it 500mA like some slow ports/chargers.

I’ve charged both the Soonfire and ncr18650a to 4.2v volts in a Nitecore I4 charger. With the F1 I tried the regular 1 amp iPhone power adapter and a 2.4 amp iPad adapter, multiple micro-USB wires, and even tried a few different wall outlets. Nothing helped.

Charger can certainly charge at a lower rate … —-
It can not how ever generate more power out , than goes in ( and on paper that’s 2.5Watt )

Again not taking into consideration lots of nasty variables …

But lets say your battery is at a resting voltage of 3v because you had too …

2.5watt divided by 3 volts = 0.833333333 ………… Amps ( not taking into consideration lots of possible variables )

At 3.5v = 0.715 A
At 4v = 0.625 A
4.1 = 0.61 A

These are not actual figures , but rather paper figures based on Claims by manufacturer ( Maximum ) , and there will be lots of variables that will change these figures in the real world …

I would suggest something like a Charge doctor to monitor the charger , at lest you will know Voltage and Amps going in to the charger … ( Ball park - variable being accuracy / quality of the Charge Doctor )

Those nasty variables !

“≥” means “greater than or equal to”

Anyone else test their F1?
Thanks

I got mine from Banggood. It will only charge up to 4.12 volts on some cells and only up to 3.86(!) volts on others.
I left the cells in the F1 for more than 8 hours. Btw, my cells are all good quality ones

I got my F1 but i havent got my batteries, will do as soon as I get them and update. regs

I’ve gotten anywhere from 4.04v to 4.09v, could possibly be even lower on some of my older cells which I haven’t tested. Would you guys return the product at this point or no? I kind of tore the packaging up lol

It was supposed to charge to 4.2v. Since it doesn’t behave the way it’s described you should be able return it or get a replacement under warranty.

My floor sample stopped at 4.18V which is within the 1% tolerance advertised. And yes it charges at 1A.

4.18v is totally acceptable, I wonder if the rest of us received bunk units.

Yeah… me too. In my haste I threw away all the (external) packaging.
Now BG wants me to register for a replacement with photos of the packaging etc.
Don’t know if I am able to…

I have a UM10 and a UM20. Have tried using the Apple and Samsung wall warts as a power supply and neither worked well. Switched over to an Anker powerport 5 and all problems disappeared. It charges the UM20 with two 18650’s, two tablets and a phone all at the same time fully to 100%. Anker’s car charger works flawlessly too

Apple and Samsung make great phones, but their wall chargers leave something to be desired IMO.

Just got my batteries yesterday and tested immediately for you. Mine stops at 4.18 as well. When I insert it into the Liitokala Li500 it reads 4.18. Less than 10 secs or charging, the voltage changes to 4.20v. I guess that was the termination voltage (4.2) and the rest voltage (4.18) of my Sanyo GA.

Hope that helps. PS: Maybe you should use a powerful USB 5v charger, rated 2A? I used a Huawei tablet 2A charger and got this results.

Ok my turn to ask a question, hope you guys dont mine.

When fully charge, it only shows 2 LED lit up at 4.2V. Even when I am using as powerbank, it’s 2 LED instead of 3. Other reviews says it’s 3. Anyone has any idea why?

I have two of these chargers and mine work as described by Nitecore.

I have a usb power meter which gives voltage and amps readings and chargers that I have reduced the amps quite a bit when near terminal voltage.

My F1 charges at .5 amps at the start and goes down to .18 amps or lower at termination. Termination at 4.2 volts is NOT a gold standard.

The first battery charged by my new F1 - 4.14V.

I am returning mine to the Amazon seller, without even getting into the voltage issues, I have trouble getting the USB output to charge my devices. They will charge for a second but then stop. I had high hopes for this charger, super disappointed. Nitecore as whole possibly needs better quality control, my TM16gt mode selector button still works but has shifted internally and no longer “clicks”. I haven’t dropped it or struck it against anything.

I got one and it goes up to 4.18V. 4.08 definitely is a defect of the charger. However, if you’re using it just as a power bank it doesn’t really matter. The Li-Ion batteries are being charged according to CC/CV. When it goes up to 4.10 the CV starts taking place and the current drastically drops down increasing the charging time. I’d not care even if it doesn’t go up from 4V. I use the charger for high drain current batteries for vaping mech mods. That’s where the 4.08 is really a damn deal. You need the higher wattage in vaping to make outstanding clouds according to W=V^2/R formula. With vaping the battery at its nominal 3.7V is usually thrown into a charger.

About this tricky >= 500mA. If you download this single page manual from their official site you’ll see the tempo of blinking lights. There’re 2 variants: you got slow = 500mA and fast (2Hz) = 1000mA. Depending on the wall plug AND the cable itself I was able to run the 1A here. It’s kinda wack, but my Apple wall plug runs less current than my laptop USB port.