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Thread: Ultrafire WF-188 TEST !

  1. #1
    Flashaholic* old4570's Avatar
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    Default Ultrafire WF-188 TEST !

    I like the sliding contacts , they feel nice , I just wonder a little about the long term + there is no problems with any 18650 I can think of , they all will fit with room to spare [ Yes even the Xtar 18700 with room to spare ] .

    The only issue I have is the design of the cradle , if you knock the charger the battery may very easily be dislodged , so just bear in mind the batteries are not held in place very securely .

    Now the the charger has sliding tabs for adjusting charge current and voltage range , I really hated them with a passion , they just screamed cheap to me , so when I opened the charger for some pictures I was some what remiss in putting them back when closing the charger , Im much happier with the tabs removed , allowing me access to the switches directly .
    The charge chord seems to be a euro plug equipped one , so might be something to bear in mind .


    By old4570 at 2011-01-01


    By old4570 at 2011-01-01


    By old4570 at 2011-01-01

    I will update as I complete the battery charging tests .

    OK some charging info :

    650mA setting =

    18650 Battery @ 3.79v - 600mA charge current
    18650 Battery @ 4.11v - 350/360mA charge current
    18650 Battery @ 4,18v - 290/300mA charge current

    300mA setting =

    18650 Battery @ 3.79v - 300mA charge current
    18650 Battery @ 4.11v - 300mA charge current
    18650 Battery @ 4.18v - 290mA charge current

    Ive been runing tests on the 650mA setting , and when the charger terminates , its @ 4.21v/4.22v and once the light goes green it actually stops charging , I could not measure a charge current on termination .

    There does seem to be an issue though , early termination . For some reason some batteries are terminating @ 4.14v/4.15v whilst others go 4.21/4.22v , it does not appear to matter whether the cells are protected or not they may fully charge or not . I dont know if this charger has resistance sensing and terminates early because some cells may have more internal resistance as they approach full charge , or whether its an issue with the sliding terminal and the way it is set up with a rail type system [ see pictures ] . Anyhow , I will explore this when I have done the 300mA tests . If it turns out to be some sort of resistance sensing , then it can be used to sort out your good cells from the not so good ones , but if this were your only charger it could leave you with a lot of undercharged batteries .

    Currently testing 300mA setting :

    There is no joy with the 300mA charge setting , it looks like early termination at 4.11volts on both channels .
    Im going to mod the charger now to eliminate the rail system as a possible cause of the early termination , so keep an eye out , also I will take a video with the amp meter connected .
    Last edited by old4570; 03-10-2011 at 05:25 PM.

  2. #2
    Flashaholic* old4570's Avatar
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    Default Re: Ultrafire WF-188 TEST !

    Modified UF-WF188


    By old4570 at 2011-01-01

    Hopefully the pictures tell a thousand words .
    I wanted to eliminate the rail as a source of problems with the termination voltage , so I did a mod to directly wire up the negative sliding post to eliminate any possible contact problems that may result in causing an early termination . I did the mod to both sides , so both sliding posts are now hard wired . I will re test to see what happens .

    Did it help ? Thats a good question , it would seem some cells are stopping at 4.17v now rather than 4.14/4.15v , problem with testing chargers is you end up with a lot of charged cells and not many empty ones , slowing down the testing as you try to drain cells so you can charge them back up .

    If your desperate for a charger that can handle larger batteries , then I would reluctantly say go for it , but dont expect a flash product , I think the folks that made this charger need to go back and do there home work , because near enough is not good enough . Im still testing , and it might take a while longer to get the full picture , reporting on the fly can be a little hit and miss , but knowing that people were interested , well .
    Im currently re-testing to see what difference the mods make , and It will take a little while .

    Its early day's : But looks like "BINGO"

    Ive been testing on the 300mA setting , and the batteries are now coming of the charger @ 4.17 lowest and 4.21v Highest ..

    I did two a moment ago and they came off @ 4.2 and 4.21 , this is a serious improvement over 4.11v ..

    I want to do some more testing to see what voltages I get , but this is much more like it , this is more in line with the sort of results I get with the WF-139 , the Trustfire TR-001 .

    Its early , but it looks like the rail method of powering the moving negative post is just causing problems , I want to charge some more batteries @ 650 and 300 to make sure the charger is behaving as it should , but it looks like I found the problem . But for now , some more tests
    Last edited by old4570; 03-10-2011 at 05:22 PM.

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    *Flashaholic* kramer5150's Avatar
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    Default Re: Ultrafire WF-188 TEST !

    Thanks... looking forward to this thread.
    So its a CC profile fixed at either 300 or 650ma?... and there is no CV profile?
    CLICK HERE for my flashlight reviews.
    PAUL KIM... AN INDUSTRY GENIUS

  4. #4

    Default Re: Ultrafire WF-188 TEST !

    good!

    waiting for your results...


  5. #5
    Flashaholic* old4570's Avatar
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    Default Re: Ultrafire WF-188 TEST !

    the 300mA setting may be Constant Current , as it looks like it tries to maintain the 300mA charge rate for as long as possible , Constant Voltage , it looks like it maintains a voltage of 0.04v over the battery voltage .

    So if a cell is say 4.12v , the voltage will be 4.16v when on the charger , open voltage is 4.7v .. [ Currently on 300mA setting - so will retest @ 650mA ]

    The charge method appears to be the same as with the WF-139 , I will take a video shortly .

    OK actually there seems to be a bit of a pulse [ maybe as it checks the batt ] so it actually might be 4.16v then it will drop to 4.14v and than back up to 4.16v as it goes along . [ 300mA ]
    @ 650mA setting with the batt @ 4.13v it seems to be pulsing 4.2v - 4.19v - 4.2v
    Last edited by old4570; 07-12-2010 at 09:20 PM.

  6. #6
    Flashaholic* old4570's Avatar
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    Default Re: Ultrafire WF-188 TEST !

    Update : The day is drawing to a close , Ive run out of half charged cells and now need to drain them as I go .

    So far = the 300mA setting to start with , the charger seems to maintain 300mA for most of the charge cycle , only problem is it seems to terminate at 4.11v [ before mod ] . This is ok for 10440 cells but not 18650's

    650mA setting , the charger seems to terminate all over the place , 4.13v 4.14v 4.15v 4.16v 4.17v 4.18v 4.19v 4.21v 4.22v , in fact it seems to terminate everywhere but 4.2v

    One battery has been through 3 charge cycles in this charger , it terminated @ 4.14v 4.17v and 4.22v , its almost like termination voltage is a lottery .

    My Wow18650 is in its 3rd cycle as I type this , 1st one terminated at 4.21v second one terminated at 4.17v and Im taking money on where it terminates next . My red Ultrafire 2600 Protected has been through two charge cycles , the first one it terminated at 4.17v and the second time 4.22v .

    If you guys dont like the WF-139 , I dont know what your going to think about this one ?

    I think who ever came up with this charger , really needs to actually charge some cells with it before putting it on the market , I cant believe for a moment that this charger was fully tested

    I think the search continues for a Good 18650 Li-ion charger , how hard can it be to make a charger terminate charging at 4.2v
    At least some one should consider installing trim pots so that users can tune the charger themselves , id gladly pay an extra dollar for such a option .

    I will continue testing , and if there is anything new to report , I will do so ASAP , but for now , I remain somewhat un-impressed .

    Above impressions are for the stock charger : I am re-testing after doing mods :
    Last edited by old4570; 07-13-2010 at 06:28 AM.

  7. #7
    *Flashaholic* mdocod's Avatar
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    Default Re: Ultrafire WF-188 TEST !

    Thank you for testing this charger.

    To point out a possible "bright side" if there is one....

    I'd rather own a charger that terminates ALL OVER THE PLACE between 4.12 and 4.22V than some of the other chargers I have tested, that will trickle and hold cells at 4.26V all day and all night.

    Quote Originally Posted by old4570
    OK some charging info :

    650mA setting =

    18650 Battery @ 3.79v - 600mA charge current
    18650 Battery @ 4.11v - 350/360mA charge current
    18650 Battery @ 4,18v - 290/300mA charge current

    300mA setting =

    18650 Battery @ 3.79v - 300mA charge current
    18650 Battery @ 4.11v - 300mA charge current
    18650 Battery @ 4.18v - 290mA charge current
    Are these charging voltages or resting voltages?

    ----

    We can learn a lot more about the charger if you take advantage of those long bays, and cram the multi-meter leads in there while it's charging, taking voltage measurements and seeing what happens.

    I think it would be interesting to see what type of charge method is occurring there.

    Eric
    -Eric

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    Flashaholic* old4570's Avatar
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    Default Re: Ultrafire WF-188 TEST !

    Quote Originally Posted by mdocod View Post
    Thank you for testing this charger.

    To point out a possible "bright side" if there is one....

    I'd rather own a charger that terminates ALL OVER THE PLACE between 4.12 and 4.22V than some of the other chargers I have tested, that will trickle and hold cells at 4.26V all day and all night.



    Are these charging voltages or resting voltages?

    ----

    We can learn a lot more about the charger if you take advantage of those long bays, and cram the multi-meter leads in there while it's charging, taking voltage measurements and seeing what happens.

    I think it would be interesting to see what type of charge method is occurring there.

    Eric
    Voltage is measured battery voltage : [ out of charger - so actual batt voltage ]
    @ 300mA setting and charge voltage was 0.04v over batt voltage .
    @ 650mA setting its higher , 0.07v over batt voltage

    Charge method appears to be the same as the WF-139 , I will video tape the Multi meter when time permits , to see if it pulses like the WF-139 ..
    There does appear to be a voltage pulse , which may be matched by a current pulse .

    My WF-139 charges to 4.2v or a little less and then stops , does whats required , but people still po po it . Guess the later ones have to live down the earlier ones ...

    Still not impressed with a charger that terminates like a lottery number picker , especially considering the WF-139 is as consistent as any charger you care to name .
    This charger should have been in improvement , not a step backwards .
    Last edited by old4570; 07-13-2010 at 04:15 AM.

  9. #9
    Flashaholic* old4570's Avatar
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    Default Re: Ultrafire WF-188 TEST !

    http://www.candlepowerforums.com/vb/...38&postcount=2

    Check out post 2 : Its late , time for bed , I will test some more tomorrow !

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    Flashaholic* Black Rose's Avatar
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    Default Re: Ultrafire WF-188 TEST !

    Quote Originally Posted by old4570 View Post
    I think the search continues for a Good 18650 Li-ion charger , how hard can it be to make a charger terminate charging at 4.2v
    If the Xtar WP6 charger lives up to it's specs, we might finally have the holy grail for low cost Li-Ion cradle chargers that actually charge properly (CC/CV).

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    Flashaholic* jasonck08's Avatar
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    Default Re: Ultrafire WF-188 TEST !

    Quote Originally Posted by Black Rose View Post
    If the Xtar WP6 charger lives up to it's specs, we might finally have the holy grail for low cost Li-Ion cradle chargers that actually charge properly (CC/CV).
    While it does look like an interesting charger, I still prefer my Tenergy Accucel-6, which is also about $30. Only thing is you need to make your own charging cradle.

    Regarding the Ultrafire charger, it looks like a CC charger, but not a CC/CV charger. A proper CC/CV charger should slow the charging current down to about 50-100mA once the cell hits about 4.10v, and should continue charging at this rate till it reaches 4.20v.

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    Flashaholic* old4570's Avatar
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    Default Re: Ultrafire WF-188 TEST !

    On the 650mA setting it does ease of on the current , but it maintains 300mA almost to the end , so far Ive concentrated on the Termination voltage and now that it seems to be sorted I can start looking at other things .

    But I like the fact that it maintains 300mA [ rather than 100mA or 50mA ] for as long as it does as it really speeds up the charge cycle , I really hate waiting 2 hours for the battery to be toped up .

    Im just testing termination voltage a little more today to make sure its ok , then I will get a little more into the nity gritty , and I will try and chart the charge voltage and current .

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    Flashaholic* jasonck08's Avatar
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    Default Re: Ultrafire WF-188 TEST !

    It might be fine, but who knows instead of getting 500 cycles off a quality Li-ion, one might only get 200 cycles by using a charger with a fairly high current CV stage. I don't know a whole lot about the correct charging algorithm, but I have read through several Sanyo and Panasonic datasheets, and I believe it is usually recommended to finish the charge with ~50-100ma current for a 18650 cell.

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    Flashaholic* 45/70's Avatar
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    Default Re: Ultrafire WF-188 TEST !

    Quote Originally Posted by jasonck08 View Post

    Regarding the Ultrafire charger, it looks like a CC charger, but not a CC/CV charger. A proper CC/CV charger should slow the charging current down to about 50-100mA once the cell hits about 4.10v, and should continue charging at this rate till it reaches 4.20v.
    Not exactly correct. A charger using a proper CC/CV algorithm will switch to CV, once the voltage of the circuit (cell inclusive) reaches 4.20 Volts, ending stage 1 (CC). During stage 2 (CV) the voltage will be maintained @ 4.20 Volts and the current will decline to no lower than 0.03C (where "C" equals the original charging current), at which point the charge will terminate. As such, there is no "proper" voltage to which a cell will be charged, using a proper CC/CV algorithm. The termination voltage is determined by the age, condition of the cell, and the charge rate used during charging. Older, well used cells charged at a fast rate will terminate at a lower voltage than newer cells in good condition charged at a slow rate etc.

    It looks like the WF-188 is just another attempt at assembling inexpensive components that result in yet another inferior charger that kills older used cells by not using a proper algorithm, forcing cells to a ~4.20 Volt termination, regardless of their condition. It'll work, but why bother?

    Dave

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    Default Re: Ultrafire WF-188 TEST !

    The results are basically what I expected. The charger is similar to a WF-139 but with selectable voltage and charge current so no CC/CV. SheKor still seems the best cheap li-ion IMHO (I don't consider a hobby charger, Pila or the Xtar cheap) although no selectable voltage and charge current and you do need to fix the spring flaw if you want proper operation.

    Of course some may prefer a charger with such a charging profile for high speed charging like old4570.
    Last edited by Nil Einne; 07-13-2010 at 09:09 PM.

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    Flashaholic* old4570's Avatar
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    Default Re: Ultrafire WF-188 TEST !

    Quote Originally Posted by Nil Einne View Post
    The results are basically what I expected. The charger is similar to a WF-139 but with selectable voltage and charge current so no CC/CV. SheKor still seems the best cheap li-ion IMHO (I don't consider a hobby charger, Pila or the Xtar cheap) although no selectable voltage and charge current and you do need to fix the spring flaw if you want proper operation.

    Of course some may prefer a charger with such a charging profile for high speed charging like old4570.
    I like more , my fav is the soshine 1A charger , though it does back off a lot more as it approaches 4.2 ..

    And this charger does not force older cell to 4.2 ??? What would give anyone that idea ? , if anything this charger seems very sensitive to any resistance to charging , and terminates early ..

    My older cells are terminating 4.15 4.17 , any cell with higher internal resistance , terminates before 4.2v

    ????? Quote 45/70
    It looks like the WF-188 is just another attempt at assembling inexpensive components that result in yet another inferior charger that kills older used cells by not using a proper algorithm, forcing cells to a ~4.20 Volt termination, regardless of their condition. It'll work, but why bother?

    Sorry bud , but what gave you this idea ?
    This charger does anything but .

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    Flashaholic* 45/70's Avatar
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    Default Re: Ultrafire WF-188 TEST !

    Quote Originally Posted by old4570 View Post
    Sorry bud , but what gave you this idea ?
    This charger does anything but .
    Ive been runing tests on the 650mA setting , and when the charger terminates , its @ 4.21v/4.22v and once the light goes green it actually stops charging , I could not measure a charge current on termination .
    ......For some reason some batteries are terminating @ 4.14v/4.15v whilst others go 4.21/4.22v.....
    Ive been testing on the 300mA setting , and the batteries are now coming of the charger @ 4.17 lowest and 4.21v Highest ..
    I did two a moment ago and they came off @ 4.2 and 4.21 , this is a serious improvement over 4.11v ..
    650mA setting , the charger seems to terminate all over the place , 4.13v 4.14v 4.15v 4.16v 4.17v 4.18v 4.19v 4.21v 4.22v , in fact it seems to terminate everywhere but 4.2v

    One battery has been through 3 charge cycles in this charger , it terminated @ 4.14v 4.17v and 4.22v
    My Wow18650 is in its 3rd cycle as I type this , 1st one terminated at 4.21v ......the first one it terminated at 4.17v and the second time 4.22v .
    Gosh, old, I really have no idea.

    Seriously, I get what your saying about the WF-188 terminating all over the place. I do, really. My point though, is that this charger seems to at least attempt to, in some fashion, try anyway, to terminate the charge by voltage, of sorts.

    As I pointed out in my last post, the charging circuit voltage, or the cell's OC voltage, either one, is not how termination of charge is determined when properly charging Li-Ion cells. The voltage of the cell has nothing to do with it. Termination of charge occurs when the charge rate drops to 3% (or 10% with most hobby chargers) of the CC charge rate during the CV stage when using a proper algorithm. Some how, I don't really get the impression that that is what this charger is doing, rather it would appear that it works similar to all their other chargers and just attempts to charge the cell to a certain voltage. This voltage figure has varied widely in the history of UltraFire chargers, as you are well aware of.

    Dave

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    Flashaholic* old4570's Avatar
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    Default Re: Ultrafire WF-188 TEST !

    Quote Originally Posted by 45/70 View Post
    Gosh, old, I really have no idea.

    Seriously, I get what your saying about the WF-188 terminating all over the place. I do, really. My point though, is that this charger seems to at least attempt to, in some fashion, try anyway, to terminate the charge by voltage, of sorts.

    As I pointed out in my last post, the charging circuit voltage, or the cell's OC voltage, either one, is not how termination of charge is determined when properly charging Li-Ion cells. The voltage of the cell has nothing to do with it. Termination of charge occurs when the charge rate drops to 3% (or 10% with most hobby chargers) of the CC charge rate during the CV stage when using a proper algorithm. Some how, I don't really get the impression that that is what this charger is doing, rather it would appear that it works similar to all their other chargers and just attempts to charge the cell to a certain voltage. This voltage figure has varied widely in the history of UltraFire chargers, as you are well aware of.

    Dave
    Some of it was the rail used to transmit power to the sliding post .
    But this charger does not charge to 4.21 or 4.22 every time .
    It is the goal of chargers to charge to 4.2v , its what there designed to do .
    This charger seems very sensitive to internal resistance , so if there is any resistance to charging this charger seems to terminate early .

    Only time will tell , but so far , especially with older cells , they are not making it to 4,2v or higher , only a few good cells made it there ..
    WOW18650 went 4.17v 4.21v and 4.22v
    Fireworm Went 4.22v , one of my Xtar went 4.22v another went 4.21v ..
    My older Trustfire Grey and Ultrafire grey all terminated around 4.15v to 4.17v , I had to put them in the Trusfire charger to bring them up to 4.2v .

    Even my old generic Blue 18650's would stop around 4.18v and 4.17v , and they go 4.19v in the WF-139 and 4.2v in the Trustfire Charger .

    My Soshine charger has not had much of a workout as yet , only charging some of my newer cells . [ What happens when you have a charger collection ]

    I dont think this charger forces cells to 4.2v at all , in fact it might be the least likely charger in my collection to do so , thats capable of charging up to 4.22v .. My WF-139 can do 4.21v and my Trustfire can go up to 4.22v but only with cells that are very good .

    I do believe this charger needs work , its not the best tool in the shed , as it comes stock , it may be a lottery as to termination voltage , my mod has solved this to some extent and it seems more stable and consistent now .
    And I will say it once more , this charger seems very sensitive to any resistance to charging , and will terminate early with lesser quality or older cells .
    Even putting the MM to the charger to measure voltage as its charging can cause termination , and did so several times .

    I guess its my fault for posting information on the fly , and then answering peoples questions etc , + I played with the charger stock , and then modified it and posted such in the same thread ...
    I might have to re-write the whole lot , as it takes more than one day to find things out .

    And people tend to respond to different parts of the post , so information gets a little messy ...
    Bu then its also a good way to hash things out , but I will see about re-writing the entire thing .
    One of my Grey Ultrafire 2400mA batteries just terminated @ 4.19v , this is its 5th or 6th charge cycle and it terminated @ 4.13v when the charger was stock , after being moded , it terminated 4.15v , 4.17v 4.18v and this last one 4.19v , then they do say cycling Li-ions makes them better , this battery has been un used for at least 6 months or more .
    Last edited by old4570; 07-14-2010 at 01:55 AM.

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    Flashaholic* 45/70's Avatar
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    Default Re: Ultrafire WF-188 TEST !

    OK old, I'm following you, and the reasoning behind why your coming to the conclusions that you are. I also understand the reason for your modding the charger.

    Quote Originally Posted by old4570 View Post
    It is the goal of chargers to charge to 4.2v , its what there designed to do.
    But you see, this really isn't true, at least not exactly. The 4.20 Volt figure, found in Li-Ion cell white papers and wherever else it's referred to, is the "charging voltage", not the end OC voltage specification for a charged Li-Ion cell. This means that 4.20 Volts is the maximum voltage that the cell should be subjected to, when charging during the CV stage, or at any time the cell is on the charger, for that matter.

    Any charger that subjects the cell to more than 4.20 Volts at any point during charging, could be considered as being out of specification, and not following the proper algorithm for the charging of LiCo (and, as far as I know, LiMn) Li-Ion cells. Of course, we're talking about an "ideal" situation here. There is some amount of tolerance allowed.

    A charger such as the WF-139 (and it's looking like the WF-188, as well), which uses a CC algorithm and a "voltage check" to determine the SOC of the cell being charged, will effectively "force" the cell to a predetermined voltage, such as 4.20 Volts, regardless of the age, or condition of the cell, before terminating the charge. This is also the reason why these type chargers have a voltage potential higher than 4.20 Volts, as it is necessary to accomplish the task.

    I think you are likely correct in assuming that the "rails" are the cause of the WF-188's erratic termination behavior. It seems to be acting more like a WF-139, with your mod. Anyone who is familiar with slide controls that utilize rails in audio equipment, knows how well they work.

    So again, what we have with a voltage checking CC algorithm charger, is a charger which attempts to force cells to a predetermined voltage before terminating charge, which damages used, or older cells in the process. This is the reason a CC/CV algorithm is recommended. The CV stage of a proper algorithm prevents damage to the cells by terminating the charge at a point in the declining charge current, thus eliminating excessive oxidation of the electrodes and the heating up of the cells by overcharging. A proper CV stage also avoids the possibility of trickle charging, as well.

    Have you ever wondered why Li-Ion cells charged with a hobby charger never get warm? This is because these type chargers have a proper CC/CV algorithm and the cells are not being "cooked" trying to obtain a voltage that the cells are not capable of being charged to. This is true of the Pila IBC to some extent, although a byproduct of the electronics having been built into the charger itself, is that they heat up the cells to some degree.

    I never intended to hijack your thread, old, my apologies. It's just that the proper method of charging Li-Ion cells appears to be one of the most elusive and misunderstood procedures on this Forum. I think this is largely due to the fact that 19 out of 20 Li-Ion chargers discussed on the Forum, use an improper algorithm, and their popularity has caused them to be accepted as "the norm". Are they usable? Yes. Are they good for your cells? No. Are they a safety hazard? Maybe. And it's looking very much like the WF-188 is one of the infamous 19.

    Dave

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    Flashaholic* old4570's Avatar
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    Default Re: Ultrafire WF-188 TEST !

    No not a problem , if anything , healthy debate is good ..

    And I agree , the goal of the charger is to reach 4.2v .. I would love to see a charger with a trim pot that allows the user to tweak termination voltage , I think that would be fantastic .

    I just would not have used the words , "force the battery" , since I did not really notice such at all , if anything this charger ran some what cool and never seemed to really warm up the batteries very much at all .

    [ I say this as many folk notice there batteries getting a tad warm when charging = that would worry me a little ]

    And I think to a point we might be getting away from the charger and into battery behavior , cell quality , age etc , which are really not the WF-188 fault .

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    Flashaholic* old4570's Avatar
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    Default Re: Ultrafire WF-188 TEST !


  22. #22
    Flashaholic* old4570's Avatar
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    Default Re: Ultrafire WF-188 TEST !

    Youtube stuffed up the video big time .....

    Click here to download file
    http://rapidshare.com/files/407015846/CLIP0001.avi

    So I put it on Rapidshare ...

  23. #23
    Flashaholic* old4570's Avatar
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    Default Re: Ultrafire WF-188 TEST !

    Ok Lets try and condense this :

    Unmodified : 300mA charge setting [ 3.7v = 4.2 charged ]

    Pretty much charges @ 300mA to termination , might drop a little moments before actual termination , and terminated @ 4.11v ..
    Thats pretty much it ..

    650mA charge setting

    Starts at 650mA , then eases of to around 600mA as it gets to 3.8v and continues to ease of current 350/360 @ 4.11v , and pretty much holds 300mA charge to termination . Now termination was all over the place with the charger , and it may be due to the rail power system employed for the sliding post causing some sort of disruption and there by termination becomes a lottery .


    After being modified to eliminate the power rail as a cause of problems .

    300mA setting , now charges up to 4.22v [ Max voltage detected ]

    650mA setting , also charges more consistently , and again up to 4.22v .
    I charged some 2 Xtar18700 batteries , 2 Grey Ultrafires , 2 Grey Trustfires , WOW18650 , fireworm , Trustfire Red & Black , Blue Generic 2200 x 2 , for some 11 different cells , some up to 5 or 6 times over the course of the test .

    Older cells seemed to want to terminate earlier , after the mod they started around 4.15v , but as I cycled them [ charge - discharge ] they seemed to improve [ cycling does that ] and take more voltage , which to me seemed to be normal behavior for a Li-ion .

    Only the better [ newer cells ] topped 4.2v hitting 4.21 and 4.22volts .
    And at no time did I notice excessive heat or even warmth from the batteries , so I cant say I noticed any undue stress on the batteries . If anything the charger seemed a little sensitive to internal resistance and terminated early on older cells than [ say ] the Trustfire TR-001 , the WF-139 , Soshine and others would simply keep going and take the battery closer to 4.2v .

    So keep in mind this particular sample maintains 300mA current right up to termination , or near enough to , I have provided a link for the video if any one wants to watch it , http://rapidshare.com/files/407015846/CLIP0001.avi

    The youtube one bites as they re-coded it [ youtube ] , but the one you can download should show the voltage and AMP's at 3 different times in the charge cycle .

    Well , I think everything has been said , I didnt try the lower voltage [ no batteries ] , so that leaves room for some one else to step in .
    Last edited by old4570; 07-15-2010 at 02:54 AM.

  24. #24
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    Default Re: Ultrafire WF-188 TEST !

    Really appreciate you taking the time to post your findings old.
    Have been looking for an entry level universal Li-Ion charger for 10440s up to 18650s and was waiting for this last review to complete the 3 main candidates, the others being the Soshine SC-S2 and the Shekor.
    Will now go off and re-read all the reviews and make a decision which thanks to you and quite a few others will be a very well informed one.

    Thanks again.
    Gary

  25. #25
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    Default Re: Ultrafire WF-188 TEST !

    Quote Originally Posted by Nothing View Post
    Really appreciate you taking the time to post your findings old.
    Have been looking for an entry level universal Li-Ion charger for 10440s up to 18650s and was waiting for this last review to complete the 3 main candidates, the others being the Soshine SC-S2 and the Shekor.
    Will now go off and re-read all the reviews and make a decision which thanks to you and quite a few others will be a very well informed one.

    Thanks again.
    Gary
    I have the Soshine SC-S2 and this has an open circuit voltage of 4.25 volts on each of the slots ... If I take the the 18650s off when the red LEDs change to blue , the voltage is never over 4.2 volts.

    I also have a Trustfire TR-001 with open circuit voltages of 4.24 volts ... Again if the 18650s are removed when the green LED comes on , the cell voltages are never over 4.2 volts.

    I also have a Ultrafire single cell WF-137 but this never worked and I had to have a refund ... I've kept it just in case I ever need the battery slot.

    I also have a Soshine SC-S1 min that will take smaller cells ... This was bought in error last year but will be used soon on my 18500s when they arrive ... The SC-S1 min has four charging slots and will not go up to the length of the 18650s ... I tried to measure the open circuit voltages but the Red LEDs came on then changed to Green and the went off ... No voltage was measured in any of the slots ... Perhaps this needs a cell in situ to work properly ... I will know soon when my 18500s arrive.

    Personally , I prefer my SC-S1 charger to the TR-001 as it is quicker , but in all fairness either would do the job OK ... Both were inexpensive chargers.
    .

  26. #26
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    Default Re: Ultrafire WF-188 TEST !

    Thanks very much for the info March and also for your great review of the Soshine in your other thread.
    Still researching but toying with the idea of just buying different chargers to get the best performance with different size cells, much like your self and Old have done.

    Cheers,
    Gary

  27. #27
    Flashaholic* 45/70's Avatar
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    Default Re: Ultrafire WF-188 TEST !

    Quote Originally Posted by old4570 View Post
    And I agree , the goal of the charger is to reach 4.2v ..
    Yes, but I don't think most people understand that when a proper algorithm is used, once the charging circuit reaches 4.20 Volts (the cell's voltage, removed from the charging circuit, will be lower, typically ~4.00 Volts), the charging process is not complete. It is merely the end of the CC stage and the CV stage then begins. At this point, the cell is approximately 70% charged. Here is a graph showing the stages of a proper CC/CV charge, form BU. Stage 3 concerns storing cells on a charger, and is generally not used, by flashaholics anyway. Although I believe the Pila IBC has this function, it is not recommended to leave cells on any Li-Ion charger.

    The CV stage, which limits the voltage to ~4.20 Volts, continues until the current drops to 0.03C, or 3% of the CC charge current, at which point charge termination occurs. Typically, the CV stage takes about as long as the CC stage. This depends on the CC charge current and the original SOC of the cell. With a high CC charge current, the CV stage will be longer, with a low CC charge current, the CV stage will be shorter.

    On average, the CV stage takes about as long as the CC stage, and keep in mind that the charging circuit voltage remains at 4.20 Volts throughout the CV stage. The current on the other hand, will gradually drop lower and lower. If your initial charge current (CC) is 1000mA, the charge current will eventually drop down to 30mA (100mA, or 0.1C with most hobby chargers), at which point the charge will terminate.

    What the WF-188 appears to be doing, is basically the same as a WF-139. It has no CV stage, but is a CC charger with pulsed voltage checking. Again, this type charger forces current into the cell until the target voltage (of the cell, not the circuit, via voltage checking) is reached. As the resistance of the cell increases, approaching a full charge state, the current may drop a bit, but it's still forcing current through the cell. Again, this is why a CC/CV algorithm is preferred. With a proper CC/CV algorithm, the charge is terminated based on the current acceptance of the cell, and not voltage, thus eliminating excessive oxidation of the electrodes and heat buildup.

    If the cells your using haven't been used that much and aren't that old, you likely will only notice a slight warming of the cell when it approaches a full charge state. It is with used cells that cell heating will be most noticeable. The more cycles and age on the cell the more cell heating will be noticed when using this type of charger.

    And I think to a point we might be getting away from the charger and into battery behavior , cell quality , age etc , which are really not the WF-188 fault .
    Well, if you're suggesting that the WF-188 only be used with new cells, that's a different matter! However, in this case, I'd still prefer a charger with a proper algorithm.

    Dave

  28. #28
    Flashaholic* old4570's Avatar
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    Default Re: Ultrafire WF-188 TEST !

    Well , not at all .

    But as mentioned , this charger does terminate before 4.2v with older cells , after the mod , the lowest was 4.14v , only after cycling said cell 4 times did it go up to 4.19v .. So this charger does not really force older cells to 4.2v , it actually does terminate charge earlier when it meets increased resistance to charging , in this regard it is much better than the WF-139 .

    And cycling Li-ion cells does seem to condition them to accept more charge , this is normal Li-ion behavior [ in fact many batteries can benefit from cycling ] .

    So if you have cells that have sat on the bench for 6 - 12 months and you threw them in this charger [ which is what I did ] you might find they terminate under 4.15v [ which did happen ] , and cycling them [ charge - discharge ] will improve there charge capability [ mine came up to 4.19v ] .

    I think this is a bad charger , but not because of the way it charges , but rather from the power rail design for the sliding negative post , but like I said , if you dont like the WF-139 , you wont like the WF-188 .

    I have nothing against the WF-139 , except for it being battery challenged [ wont take longer 18650's ] , and after modifying the WF-188 , its growing on me , as I really like the way it charges and maintains 300mA to termination .
    As to whether this is good or bad , at this time I cant say , I cant see it being at all bad , I guess it all comes down to opinion and personal preferences , which is fine . For now , I will keep using it , and if cells start to deteriorate and die , ill be sure to let you all know . For now I would say this charger might be good for larger cells , 17670 18500 18650 22500 etc up to 26500 . For smaller cells , 14500 16340 18350 10440 , the 300mA charge setting may be ok , I say may , I will throw in a 10440 on the 300mA setting when time permits and see what happens , as the one Im using ATM has a lot of resistance to charging over 4.1v [ possibly due to being such a small cell ]

    But for now Im all WF-188'ed out ... And it seems Im rehashing stuff we have been over ..

    Time for some

  29. #29
    *Flashaholic* mdocod's Avatar
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    Default Re: Ultrafire WF-188 TEST !

    Quote Originally Posted by old4570 View Post
    It is the goal of chargers to charge to 4.2v , its what there designed to do .
    Unless you design it to charge to 4.1V to extend cycle life 2-4 fold

    There are a lot of people on CPF who have a large quantity of cells that sit in wait, as backups, charged up ready to go. A charger that would stop at 4.10V would leave these cells in a better state to be stored. Even for daily use topping up to 4.10V would increase the life of the cell dramatically.

    The goal of the charger is to get there correctly and terminate correctly. The point where it terminates is personal preference and there are legitimate arguments for termination points from 4.05V all the way up to 4.25V depending on application.

    I dontthink this charger forces cells to 4.2v at all
    A typcal 18650 protected cell will have about 100-200mOhm total resistance depending on temperature, age, quality, etc.... Lets call it 125mOhm for this example....

    You measured basically 300mA flowing into a cell that you measured off the charger at 4.18V.

    How much potential is required to get 300mA to flow across 125mOhm?

    xV/0.125Ohm=0.3A

    Solve for x. x is the difference between the cells state of charge and the charging voltage.

    x = ~0.04V, charging voltage was ~4.22V at that time. If you got the cell to go up to 4.20V, then the charging voltage would have been 4.24V.

    Historically speaking, the WF-139 style charging has not caused charging voltages much in excess of 4.25V on most low resistance cells, like large 18650s and such. On smaller cells, where you have much more resistance (0.5 ohms and higher), like an RCR123, the charging voltage can be as high as 4.40V. In those cases, it is almost always the PCB that terminates the charge.

    Regards,
    Eric
    -Eric

  30. #30
    Flashaholic* old4570's Avatar
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    Default Re: Ultrafire WF-188 TEST !

    I ran a 10440 through on the 300mA setting and it terminated at 4.08v . I think this confirms that this charger terminates earlier with cells that offer greater resistance to charging .

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