Nitecore F1 stops charging at 4.08v! Defective?

Tried a 2600 mah “Soonfire” battery and it only came out to 4.04v. Rather disappointed. Can any F1 owners chime in or have their own measurements?

Well, it seems to me that the F1 charges at about 500mA so even if you iPad PS can supply more than 2A it woill not affect the charging time.
Your battery is about 3000mAh, so it will take 3000/500=6 hours to charge it full…
Since the F1 stops below 4,2V (not great :frowning: ) it takes a little less time

The only problem here is the 4,08V instead of 4,2V

That makes sense. I thought I read the F1 had a 1 amp charge rate for the battery but I guess not. Not terminating charge at 4.2v is really bumming me out.

From Nitecore product page… it only draws 500mA from USB so it won’t push more than 500mA through your battery, sorry

Doesn`t that pic say that 500mA is the minimum it draws?

Batteries WILL drop from the ‘so called….magic……incredible….holy grail’ 4.2v after you pull them from the charger. HJK has told us that over and over and over again. It ain’t a big deal. :wink: My charger do not charge LiIon to 4.2V, is it faulty?
Some VERY respectable authorities have confirmed beyond doubt that you will get MORE LIFE from you cells if you keep the charge like from 20-80% - don’t fully charge, don’t overly discharge. Yet people get their panties in a bunch if they don’t see EXACTLY 4.2000000v after a charge. 0.01v too little or too much and they are all upset.

So, depending on the accuracy of your voltmeter (how accurate is that?) you may be quite close to a decent fill. You certainly aren’t hurting anything and you are giving up almost nothing functionally. Another way of looking at it is that you have a superior charger that is improving the longevity of your cells. :smiley:

OTOH, I have 2 opinions;

  1. Come on, that’s a winky little charger that has very limited output. It will always take awhile on high capacity cells. You want a decent charger, get a decent charger.
    Is yours defective? Possibly, but only marginally depending on your opinion. HJK has not done a review so I can’t help you there. Cheap chargers get cheaper components and less care in assembly. Being off a bit in this price range is almost to be expected.
  1. Soonfire? Are you serious? I’d be surprised if that wasn’t crap, which likely has nothing to do with your charging problem.

All this seems correct. Also the 18650a is a older design cell. Is this one an old cell?

That seems odd. Nitecore normally makes good chargers… do you have more cells to try with?

Low termination often means old battery or high internal resistance…

4.04V is way lower than HKJ has measured. A reasonable voltage once settled is still above 4.1 (usually above 4.15).

Anyway, the easy way to determine whether this is a defect is to read the voltage immediately when charging finishes. If it isn’t 4.15V or above, I would RMA the unit.

To me that says that the available input current must be greater than or equal to 500ma.

The features posted at Illumn says that it will charge at a rate up to 1A (1,000ma).

I have been looking at picking up this charger due to its size and features. Very useful for backpacking multi day trips. Especially when you consider that you could power it with a folding solar panel.

Here is a review that WoodsWalker did over on CPF:

Nitecore F1 Flexible Charger Review. Field tested! | Candle Power Flashlight Forum


Yes it's supposed to charge at 1.0A if you provide it with enough power. What are you using to measure the battery voltage? Have you tried a different USB wall adapter?

Output: 1000mA MAX (slot), 1000mA MAX (usb)

4.04v is the Soonfire. I’d consider that battery suspect until proven otherwise. The Panasonic was 4.08. HJK indicated in the linked review that things generally settle down to 4.1something. Seems to me the charger is not off much more than 0.05-0.08, again depending on the accuracy of the voltmeter.

The unit costs $10. I personally wouldn’t bother with RMA at that price range unless the seller would simply replace it.

Looks to me like the unit charges the battery at 0.5A. Used as a powerbank it will output up to 1.0A.

DC 5V, ≥500mA

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

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?

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