Review : Xtar VC2 battery charger

[old4570]

Xtarlight.com was kind enough to send me the VC2 for review ..

VC2 Charger Product page .



If you have not become familiar with Xtar chargers , then it may be time you did ( Perhaps a bold statement on my part , perhaps not ! )

Xtar has been putting in some serious effort in the field of battery chargers for flashlight enthusiasts , and it would not be wrong to say they are taking a leading role in making chargers more user friendly , safer , and informative to prospective users . Im not going to bore you with every detail , that is what the link to the product page is for .

The VC2 is a full sized charger capable of handling the 18700 and 26650 batteries , as well the 16340 ( more latter ) . As well the features built into the charger make it well worth a careful look . Lets start with soft start ( I really like this feature ) .

Most chargers on the market start off at high current when the battery is depleted ( lets say 1Amp ) and as the battery charges the charge current progressively lowers , especially as the charger approaches 4.2v or cut off . Now its nice to have a fast charger , but often these chargers are not that fast at all because the current towards the end is so low , the process can be drawn out by over an hour , making the high current fast charger not really that fast after all . Now I was talking about soft start here .

When a battery is depleted ( low voltage ) , the lower the depletion the more stress the battery is under ( if you let me call it that ) . Is high current a good idea when the battery is in a state of low voltage ? Perhaps not , and to this end Xtar has built in soft start . The charger charges more gently , giving the battery time to absorb the energy more efficiently . This can only be good for long term battery life . Also the charger analyses the battery , checking a batteries health and charging accordingly .

You might think this bogus ! But I charged all my 16340 and one battery it refused to charge .. Over and over again I tried to force the charger to charge the battery and the charger refused every time .. In the end i pop'ed the battery into another charger for a quick charge and then put it back in the VC2 which refused to charge it . I gave up and walkied out of the room for a minute ( to get a drink ) and when I came back and picked up the battery , it was in a state of Thermal runaway !

I walked very quickly to the back door and tossed the 16340 out the door .. I then got a container of water and put the battery in it for a few hours . The battery didn't flame or explode but certainly the potential was there ! And the Xtar VC2 refused to charge that battery , if I had not been stubborn , there would never have been a situation . But now we know dont we , the VC2 can pick up on bad batteries . Because I was the test dummy .

Charging and discharging :

For three days , I kept charging and discharging a AW16340 that was 5 or more years old ..

I put it in my Turnigy Hobby charger and discharged it @ 500mAh , then I would rest it and charge it in the VC2 .. The charger was extremely consistent , my first discharge returned 500mAh capacity , the second returned 494mAh and after that it climbed slowly to where I got 510mAh capacity from the last discharge ( to 3v @ 500mAh ) . The only time I got a soft start was when I pulled the battery from the discharge and put it straight in the charger ( VC2 ) without any rest ( allowing the voltage to find its resting voltage ) . This meant the battery was still under some stress and the charger made the appropriate change to the charge current . To date I have not seen the charge current increase ( single cell ) when soft starting , so if the charger starts @ 350mAh then for me it has continued at that rate to completion .

Soft Start :

I have already mentioned that for me , if the charger soft started it did not increase the charge current but rather maintained it to completion. There are two reasons for the charger to soft start that Im aware off . Voltage state of the battery . If the voltage is low ( much under 3.8v ), the charger may soft start , and the second is battery condition . The nice thing is that the charger shows you the battery voltage before it begins to charge . And it also shows you the termination voltage , well there about's as the increments ( V ) are a little large , but still very much a ball park figure . If you are charging a battery and it soft starts , wait till you reach about 3.8v and restart the charger and it should revert to a 500mAh charge rate .

VC2 :

The VC2 certainly gives the prospective new owner some important information .

The starting voltage , termination voltage , how much current went into the battery and if the voltage is high enough and the charger soft starts this could be a indication of a bad battery . If its due to very low voltage then perhaps you need to charge batteries earlier . On termination I saw no trickle charge going to the battery , so how you feel about leaving a battery in the charger ?




http://youtu.be/Elzrcr9huNI




Conclusion :

I have spent more than 3 days charging batteries to get a feel for this charger . And I have only two negative thing to say about it , it really wants two current meters to match the voltage meters , so you can read each channel independently . This is after all a two channel charger , so why the current gauge is shared between the two channels ? That's my gripe ..

The 500mAh charge rate for me is acceptable , but for many it may be an issue one of two ways . For larger batteries it may be a little on the slow side ( sitting here watching a 18650 get charged very slowly ) . And for 16340 batteries 500mAh is about the maximum charge current you would want to subject the battery to , I would very much prefer around 250mAh for a 16340 myself to possibly 350mAh rather than 500mAh . But I accept the fact that when you make a charger for such a large range of batteries there needs to be compromise , and 500mAh is about as good a compromise as there is .

Over all , this is one seriously good product from Xtar . I found nothing to fault in regards to quality or design . It charged the smallest 16340 to my 18700 with no issue , it works and works well . I have no hesitation in recommending this charger , my sample is brilliant and as I sit in front of my computer typing this I am also monitoring a 18650 as it is charging . Its one thing to watch a charger and have no idea what is going on , now with a glance I have instant real world feedback from the charger .

VC2 Charger Visit the Xtar product page for the VC2 , and get familiar with its features :

Thank you Xtar ,

 

[Cyparagon]

No disassembly?

as the battery charges the charge current progressively lowers , especially as the charger approaches 4.2v or cut off.

That's because chargers go into constant voltage mode. That is the widely regarded proper way to charge cells.

I suspect yours operates this way as well, with the current readout just being a current limit, rather than a current meter. I'd probably call it garbage if it didn't follow the CC -> CV method.

When a battery is depleted ( low voltage ) , the lower the depletion the more stress the battery is under ( if you let me call it that ) . Is high current a good idea when the battery is in a state of low voltage ? Perhaps not , and to this end Xtar has built in soft start .

Is this speculation, or is there some science to this?

I watched your film, and it charged the cell at 400mA instead of 500mA. That's not much of a change.

Also the charger analyses the battery , checking a batteries health and charging accordingly .

What does it measure, and how does it change its behavior? Have you verified any of it?

and when I came back and picked up the battery , it was in a state of Thermal runaway !

I think you mean to say "It was warm". Thermal runaway doesn't really apply to batteries.

Possible explanation: Cell had a soft internal short so it self-discharges. Voltage was too low, so the "smart" charger noticed, and the "dumb" one did not, and sent constant current to the cell, heating it up.

I do not believe there is much reason to be alarmed here. The chargers' constant current would have kept the heat dissipation to a reasonable level. It would also have been detectable with a multimeter.

it also shows you the termination voltage

Uh... yeah. 4.2V. Like any lithium charger in existence. The question is how accurate is it. Have you verified it?

On termination I saw no trickle charge going to the battery , so how you feel about leaving a battery in the charger ?

I have no idea what you're trying to say here. Are you of the opinion that trickle charging is good or bad? Why? Are you of the opinion that leaving the cell in the charger is good or bad? Why?

I would very much prefer around 250mAh for a 16340 myself to possibly 350mAh rather than 500mAh . But I accept the fact that when you make a charger for such a large range of batteries there needs to be compromise , and 500mAh is about as good a compromise as there is .

You said previously that "the charger analyses the battery , checking a batteries health and charging accordingly". That is a contradiction of this passage.

Do you even own a multimeter? I hope you're not just saying "this device works, because this device says it works", because that would be embarrassing for you. Have you checked ANY of the readouts against another instrument?

 

[old4570]

No disassembly?



That's because chargers go into constant voltage mode. That is the widely regarded proper way to charge cells. Taken out of context

I suspect yours operates this way as well, with the current readout just being a current limit, rather than a current meter. I'd probably call it garbage if it didn't follow the CC -> CV method. Possibly quite so



Is this speculation, or is there some science to this?

I watched your film, and it charged the cell at 400mA instead of 500mA. That's not much of a change. Its a soft start nothing else implied



What does it measure, and how does it change its behavior? Have you verified any of it? Verified ? HTF do I verify it , I can only charge a bunch of batteries and see how the charger behaves , old batteries charge at a lower rate while newer batteries charge @ or near max , want more buy one and test it yourself



I think you mean to say "It was warm". Thermal runaway doesn't really apply to batteries. Yes a description given to emitters that overheat and attempt to self destruct - often this term is used for batteries that overheat and attempt to self destruct - a borrowed term PS/ Warm WTF do you know , if warm you mean like a oven potato , then sure , it was warm

Possible explanation: Cell had a soft internal short so it self-discharges. Voltage was too low, so the "smart" charger noticed, and the "dumb" one did not, and sent constant current to the cell, heating it up. Voltage was not too low , I measured the voltage @ around 3.6v which is just a little higher than the resting voltage of a depleted battery

I do not believe there is much reason to be alarmed here. The chargers' constant current would have kept the heat dissipation to a reasonable level. It would also have been detectable with a multimeter.??????????? Do you have a clue - Can you read ? The battery was not in the charger , I used another charger to charge the battery to force a charge ( since the VC2 refused time and again to charge the battery - 5 times it refused and then I reached for the dinosaur charger ) , and if the short occurred in an older charger , it would most likely have flamed as the charger would have contributed to the short feeding it power - Why do you think batteries explode in chargers ? But it did not happen , the older charger I used instigated the short ( it was only in the charger about 20 seconds ) , but since I pulled the battery and put it down on the table , it just got oven hot . Hence my rush to get it out the door .. I really love armchair BW's ... Go buy a VC2 and test it



Uh... yeah. 4.2V. Like any lithium charger in existence. The question is how accurate is it. Have you verified it? Its ball park because of the scale I charged over 30 batteries , none went over 4.2v , most of the older batteries terminated 4.5v to 4.15v



I have no idea what you're trying to say here. Are you of the opinion that trickle charging is good or bad? Why? Are you of the opinion that leaving the cell in the charger is good or bad? Why? ????????



You said previously that "the charger analyses the battery , checking a batteries health and charging accordingly". That is a contradiction of this passage. Nit picking good time

Do you even own a multimeter? I hope you're not just saying "this device works, because this device says it works", because that would be embarrassing for you. Have you checked ANY of the readouts against another instrument?

Wow , do I own a multimeter gee you know what - I own several , but for arguments sake - FU , ill just get that out of the way real fast since I don't like you already