Test/Review of Charger Xtar VP2

[RetroTechie]

Welcome to CPF, lagman! :wave:

I find it very confusing that the 3.6V setting charges to 4.2V.
It would be better if they had a 3.6V setting that charges to 4.1V and a 3.7V setting that charges to 4.2V.
This mistake may cause people to charge old 3.6V batteries to 4.2V which is not good...

There is no confusion or mistake here; just failing to understand the subject matter, and/or misreading the manual.

3.6V refers to the nominal voltage of a Li-ion cell. Some (like IMR aka Li-Mn chemistry) have lower internal impedance than the common Li-Co, so will -on average- output a somewhat higher voltage during discharge. Hence they're often labeled with 3.7V (or even 3.8V?) as nominal voltage.

Both these chemistries are charged up to 4.2V (so Li-Co and Li-Mn/IMR cells use the same setting). That is sort of an arbitrary value as well, which offers a good compromise between safety, utilizing capacity, and longevity of cells. 4.1V would work too.

3.2 or 3.3V nominal voltage (3.6V charge voltage) is for LiFePO4​ cells. And these days there are some cells that safely charge to a bit higher voltage (4.35V), hence a 3rd voltage setting.

 

[mr.snakeman]

delete

 

[chanjyj]

Thank you HKJ, appreciate your effort.

 

[lagman]

Welcome to CPF, lagman! :wave:


There is no confusion or mistake here; just failing to understand the subject matter, and/or misreading the manual.

3.6V refers to the nominal voltage of a Li-ion cell. Some (like IMR aka Li-Mn chemistry) have lower internal impedance than the common Li-Co, so will -on average- output a somewhat higher voltage during discharge. Hence they're often labeled with 3.7V (or even 3.8V?) as nominal voltage.

Both these chemistries are charged up to 4.2V (so Li-Co and Li-Mn/IMR cells use the same setting). That is sort of an arbitrary value as well, which offers a good compromise between safety, utilizing capacity, and longevity of cells. 4.1V would work too.

3.2 or 3.3V nominal voltage (3.6V charge voltage) is for LiFePO4​ cells. And these days there are some cells that safely charge to a bit higher voltage (4.35V), hence a 3rd voltage setting.

That's very interesting. I always heard that old li-ion cells labelled as 3.6V were charged at 4.1V and that you should never charge them in a 4.2V charger.

After reading your reply I did some researches and didn't find any serious (other than forums) source that says that old li-ion were charged to 4.1V.

Thanks, I learnt something.

 

[ChrisGarrett]

That's very interesting. I always heard that old li-ion cells labelled as 3.6V were charged at 4.1V and that you should never charge them in a 4.2V charger.

After reading your reply I did some researches and didn't find any serious (other than forums) source that says that old li-ion were charged to 4.1V.

Thanks, I learnt something.

Define 'old'?

I just yanked some Sony 2000mAh 18650 G4Ps with June 2002 date codes on them and they charge up fine to 4.20v. Those are 12 years old and they're still working reasonable well.

Some manufacturers use 3.6v on their wrappers and some use 3.7v. If you're worried, try and find the data sheet for that particular battery.

Suffice it to say, that in today's world, 3.6v and 3.7v are interchangeable and require a charger that can charge them up to 4.20v (+/- .05v) for proper charging.

Chris

 

[HKJ]

At one time the 4.10 volt must have been the standard, because all hobby chargers uses 4.10 volt on the LiIon settings, but I have never seen a LiIon battery with 4.10 volt charge voltage (I started testing LiIon batteries in 2010).

Today the 3.6/3.7 volt marking does not say anything about charge voltage, but is supposed to be the average voltage at some specified load.

 

[lagman]

There is an example of a 3.6/4.1V battery on this page.
Notice that it is written that 3.6V batteries should be charged to 4.1V... Which leads to confusion.
I think it was about 10 years ago that batteries were charged to 4.1V... but I have no proof.

 

[HKJ]

There is an example of a 3.6/4.1V battery on this page.
Notice that it is written that 3.6V batteries should be charged to 4.1V... Which leads to confusion.
I think it was about 10 years ago that batteries were charged to 4.1V... but I have no proof.

Thanks for the link.
It does not really match hobby chargers, here Lithium polymer batteries are always 4.20 volt, it is only LiIon that is 4.10 volt (Today there is no real difference between them).

 

[mr.snakeman]

And what about the Tenergy batteries marked 3.0v.?

 

[HKJ]

And what about the Tenergy batteries marked 3.0v.?

Sounds like RCR123 batteries, please read this: www.candlepowerforums.com/vb/showthread.php?366975-CR123A-and-rechargeable-substitutes

 

[SilverFox]

Early attempts to provide a rechargeable lithium battery involved using lithium metal in the construction. These batteries had "safety problems" that rendered them unsuitable for general use.

Around 1990 Sony pioneered a lithium rechargable battery that used lithium ions instead of lithium metal. These early batteries had a recommended maximum charge of 4.1 volts. Others made improvements on the electrode materials used and the maximum charge voltage was raised to 4.2 volts. Recently more improvements have been made and the charge voltage is now up to 4.35 volts.

In 1993 the US Army ran some tests on the Sony Li-Ion batteries. The report can be viewed here.

Of interest in the report are the results of charging to higher and lower voltages, the effects of storing batteries at full charge and elevated temperature, and note that the discharge curve is different from those observed with the batteries we are now using. The Sony batteries saw the voltage gradually drop off throughout the discharge and the cells we use now have a flat spot at what we call "nominal voltage."

It is a very interesting report.

Tom

 

[mr.snakeman]

Sounds like RCR123 batteries, please read this: www.candlepowerforums.com/vb/showthread.php?366975-CR123A-and-rechargeable-substitutes

Nope, not on your list, charger model: PH-123A-3.0A

 

[mr.snakeman]

Early attempts to provide a rechargeable lithium battery involved using lithium metal in the construction. These batteries had "safety problems" that rendered them unsuitable for general use.

Around 1990 Sony pioneered a lithium rechargable battery that used lithium ions instead of lithium metal. These early batteries had a recommended maximum charge of 4.1 volts. Others made improvements on the electrode materials used and the maximum charge voltage was raised to 4.2 volts. Recently more improvements have been made and the charge voltage is now up to 4.35 volts.

In 1993 the US Army ran some tests on the Sony Li-Ion batteries. The report can be viewed here.

Of interest in the report are the results of charging to higher and lower voltages, the effects of storing batteries at full charge and elevated temperature, and note that the discharge curve is different from those observed with the batteries we are now using. The Sony batteries saw the voltage gradually drop off throughout the discharge and the cells we use now have a flat spot at what we call "nominal voltage."

It is a very interesting report.

Tom

The good old days.

 

[HKJ]

Nope, not on your list, charger model: PH-123A-3.0A

I did not expect it to be on my list, but the articles explains the reason for batteries marked with 3 volt.

 

[lagman]

Silverfox: I'm unable to open that link. (timed out)

 

[SilverFox]

Hello Lagman,

Welcome to CPF.

The link works fine for me but put

ad a277 076

into a search and you should come up with a pdf called Performance of the Sony Lithium-Ion Rechargeable Battery.

Tom

 

[Shiftyk5]

Thanks for the review HKJ, I just ordered my VP2 last night.

Can't wait for it to arrive.

 

[lagman]

The link works now... I guess the website was down for a few moments.
Interesting PDF.

 

[IsaacL]

Thanks for the all the effort and time you put into these reviews HKJ!

I'm really enjoying my VP2 charger.

 

[ven]

Well i did not realise as i await my 4.35v cells that i have some already as freebies
2x Genuine LG Chem ABC2 18650 2800 mAh Lithium-Ion Unprotected Cells
[FONT=Arial, Helvetica, sans-serif]Size : 18mm x 64.5mm
NominalVoltage : 3.8V
Capacity : 2800mAh (2680mAh min.)
Max. Charging Current : 2.7Amp (ambient temperature 25C)
Max. Discharging Current : 5.4Amp [/FONT](ambient temperature 25C)Color : Orange
Charging metod : 4.35V CC-CV - this battery need to be charged with 4.35V - CV to full capacity
Discharge Voltage : 2.75V (Cut off )
Max. Weight : 48g
Charging current : 1350mAh Standard , 2700mAh Rapid chargee
Energy : 10.35 Wh
[FONT=Arial, Helvetica, sans-serif]Flat Top Button , High Energy density

[/FONT]

So just trying them out