My charger do not charge LiIon to 4.2V, is it faulty?

Good suggestion.

You probably get about 2% more performance and 10% less battery life that way. Go for it!
I made up those numbers… O:-) but the concept is valid if not the specific amounts.

the difference is not detectable in real use and difficult to test with our equipment as there are too many variables.nit picking at its finest.

Thanks for this. Occasionally I will encounter a charger that charges slightly over 4.2, but never more than 4.25. I had wondered if this was a safe voltage. And on a side note… What is the lowest safe discharge level for a lithium ion. I’d thought it was around 2.7 for a lot of them. Is this right?

Depends on what you mean by safe (There is no risk of explosion at 2.7 volt), maybe I ought to write an article about that.

Your expertise with LiIons is very much appreciated by all of us, so if you do a post on how low a cell should be allowed to go that will meet with an equally warm reception.

Phil

Ok so it’s safe, that’s good… But what is an ideal voltage. I test many lights, some of which do not have low voltage protection… And I often wonder what is an ideal voltage… What’s a safe voltage, what’s unsafe? Below 2.7? What is the lowest voltage that is best for the longevity and health of the cell… Or what is a dangerous voltage. There is such scattered and contradictory information out there, so I’d like to know.

But there definitely needs to be an article written on the subject.

Then you aren’t going to be happy since there are many “opinions” on those numbers. IMO, and in my own practice, I try to keep the voltage above 3.0v at all times and generally above 3.2v. There is VERY little capacity under 3.0v and the volts drop precipitously after that making it a slippery slope. There just is not a lot of good reason to push that far unless you are in an emergency situation. Why bother?
Once you go under 2.5 it gets dicey. Below 2.0 you are likely getting into damage area.

You don’t get immediate problems from over discharge, you get problems from charging AFTER over discharge and the damage it may incur.

I have tested a lot of lights and have found most commonly some cutoff point is around 2.6-2.8, which is why I was wondering. I often wonder why it’s usually about this voltage. I understand there isn’t a real consensus, but I wonder why that number is common.

It’s probably/mostly ‘safe’. That does not mean it’s optimal. Just look at the voltage drop on HKJ’s discharge graphs. Your choice.

Thanks HKJ for the effort put in here for us. Lets hope everyone’s DMM’s read accurately. :slight_smile:

I finally got a charger that charges to 4.2V, i suspect the ML-10X chargers are just made with components with loose tolerances because they finish charging from 4.04-4.11V, battery tested immediately off the charger.

Its interesting to note the voltage drops slightly as soon as removed, i suppose this is not well covered on BLF (add to the li ion thread :wink: ), so my 4.20V charger right off the charger must mean its charging to 4.22ish volts. I’m not going to complain, after living with 4.04V for years i’m happy to get a full charge.

Thanks for posting this thread HKJ :beer:

I did some tests once with batteries that came of at around 4.2v versus 4.17v (Nitecore I2 and Opus 3100 respectively) and from memory the difference was about 1.8% when I discharged them on my Accucel 6. Wouldn’t be useful or noticeable in real life usage for me.

This thread needs to be sticky’ed…

I have created a setting for my MC3000, with termination at 4.25V and 50mA, newer batteries come out at 4.20V, and drops to ~4.17V a couple hours later. But I don’t think there is any real benefit by doing so other than pleasing the absurd need of achieving exactly 4.20V.

It’s great to have articles written by someone that everyone trusts, keep going hkj, and thanks for the effort :slight_smile:

Another informative HKJ thread.

Opinions and metaphors can be interesting.

But it’s immensely more valuable to have conclusions that are supported by concrete facts and measurements.

Thanks for the excellent and informative write-up HKJ
:beer:

very informative post, thanks HKJ for your effort :slight_smile:

HKJ, thanks a lot for putting this down in a nice post for reference.

It was much needed. Ought to be stickied.

That would be good, and thanks for this one.