# Ultrafire WF-139 Charger



## FatTony (Nov 12, 2007)

I finally bought one of these to charge the growing number of 18650 cells I have harvested from laptop packs but from all of the stories I hear about this over charging I have kept a close eye on it. I have charged about 20 cells now, protected and unprotected and I haven’t experienced any over charging at all.

Using unprotected cells if I pull them from the charger when the lights turn green they read exactly 4.20v, however if I leave them on the charger for several hours after the green light (monitoring heat and voltage) the cells return to room temp and steady themselves at 4.18v.

Has Ultrafire released a new version of this charger that completely stops charging when the lights go green?


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## DM51 (Nov 12, 2007)

You should carry on monitoring all charges closely, and always take the cells off the charger as soon as the light goes green, not leave them there. 

The charger is not recommended for unprotected cells because it can carry on trickle-charging after the light has turned to green, and this can result in damagingly high over-charging. 

There appear to be inconsistencies in the manufacture of these units, with some giving different results to others. You seem to have a good one if it is not taking any cells above 4.20 volts. 

Ultrafire have not released a new version of this charger AFAIK.


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## FatTony (Nov 12, 2007)

Thank you. I will continue to treat it as a risk and monitor all charges very closely.


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## j3bnl (Nov 12, 2007)

FatTony said:


> I finally bought one of these to charge the growing number of 18650 cells I have harvested from laptop packs but from all of the stories I hear about this over charging I have kept a close eye on it. I have charged about 20 cells now, protected and unprotected and I haven’t experienced any over charging at all.
> 
> Using unprotected cells if I pull them from the charger when the lights turn green they read exactly 4.20v, however if I leave them on the charger for several hours after the green light (monitoring heat and voltage) the cells return to room temp and steady themselves at 4.18v.
> 
> Has Ultrafire released a new version of this charger that completely stops charging when the lights go green?


 
I dont leave the charger unattended and always check voltage when the batteries come off. I have never had any protected cells go above 4.2v they are usually always about 4.18v-4.19v when the light turns green.
Having read a lot of threads about this particular charger it would appear that I also got a good one thankfully.


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## falconx (Nov 12, 2007)

I have ordered one of these chargers and was wondering how long on average it should take for it to fully charge a cell so i can set a timer and not forget about it. The batteries I bought are protected 3.7v 18650s (sku 6979) I was told this should charge fine with this charger. 
Btw, I would just like to verify that the negative side of the battery faces the head of a WF-600 and makes contact with the spring? This is the first light I have that hasn't got the spring in the tail so I thought I'd make sure before something blows up. Cheers


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## DM51 (Nov 12, 2007)

falconx said:


> I have ordered one of these chargers and was wondering how long on average it should take for it to fully charge a cell so i can set a timer and not forget about it. The batteries I bought are protected 3.7v 18650s (sku 6979)


If you divide the capacity of your cell in mAh by the output of the charger, you will get an indication of how long it will take. If your 18650 has a capacity of 2,250 mAh and the charger an output of 450 mA, the cell would in theory take 5 hours to charge from empty (5 x 450 = 2250). 

In practice it is not quite like that, as Li-Ion charging utilises a constant current followed by constant voltage charging cycle, so the charger's output will vary. But it gives you an approximate idea.

To get the maximum life from your cells, you should not run them down to empty each time - it is better to top them up after each use. 

You should never leave Li-Ion cells charging unattended.


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## indycrucible (Nov 12, 2007)

My WF-139 terminates charging at 4.2V also. So far, it has never gone higher than that.


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## WadeF (Nov 12, 2007)

While everyone is on the topic of this charger, this charger will safely charge AW's 14500's?


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## FatTony (Nov 13, 2007)

Yes it will as long as they are 3.7v cells.


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## Yenster (Nov 18, 2007)

falconx said:


> Btw, I would just like to verify that the negative side of the battery faces the head of a WF-600 and makes contact with the spring? This is the first light I have that hasn't got the spring in the tail so I thought I'd make sure before something blows up. Cheers


 
I'm thinking you probably already figured this out, but I briefly had a WF-600 (sent back because it wasn't the "18650 Only" version) and the positive battery terminal faces the head. Check to see if the tail is also spring loaded by pressing down on the brass terminal (the spring may be underneath it).


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## mrQQ (Dec 5, 2007)

i'm sorry for a stupid question, but since everyone keeps telling how dangerous LiIon is, i'll better be stupid than sorry  should wf-139 be making a "hiss" sound when charging batteries? the sound is in sync with red flashes - when they turn green for a split second the sound turns off, and comes back?


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## half-watt (Dec 5, 2007)

mrQQ said:


> i'm sorry for a stupid question, but since everyone keeps telling how dangerous LiIon is, i'll better be stupid than sorry  should wf-139 be making a "hiss" sound when charging batteries? the sound is in sync with red flashes - when they turn green for a split second the sound turns off, and comes back?



i have a number of chargers that make a similar sound. a small AA/AAA 4-pocket NiMh one which plugs directly into an outlet w/o using a power cord is going right now is making that noise (sometimes with NiMh chargers hi-current pulse charging might be taking place too).

even my age-degraded hearing can still pick up on the sound that you refer to.

i have to believe that it is quite normal. actually, i'm not sure that i DON'T have a charger that i can't hear some soft sound from when it's operating.

as far as i'm concerned:

sound = 'ok'
sparks = not 'ok'
smoke = not 'ok'
flame = very not 'ok'


still, i always monitor Li-ion charging and have the charger on my coal stove when the stove is not being used; elsewhere (another non-flammable surface) when the stove is in operation. good advice DM51 gives - heed it.


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## ampdude (Dec 5, 2007)

DM51 said:


> The charger is not recommended for unprotected cells because it can carry on trickle-charging after the light has turned to green, and this can result in damagingly high over-charging.



This can happen just as easily with protected cells, especially at a trickle charge rate in which the protection circuit typically won't kick in.


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## DM51 (Dec 5, 2007)

ampdude said:


> This can happen just as easily with protected cells, especially at a trickle charge rate in which the protection circuit typically won't kick in.


Most over-charge protection circuits are set at 4.25-4.30V, which is higher than a Li-Ion charger ought to go, but still within safety margins. 

AFAIK there have been no reports of good-quality protected cells being trickle-charged to >4.3V. 

Good Li-Ion chargers terminate properly at ~4.2V, and do not rely on a cell's protection circuit. 

The main problem is with the potentially dangerous combination of poor-quality unprotected cells being charged in chargers that don't terminate properly and carry on trickle-charging to >4.3V.


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## Yenster (Dec 5, 2007)

I don't have the WF-139, but I have other chargers that are rated at 4.2V output. When I measure the actual output with my DMM, I see that they measure at 4.24V. So I'm guessing that it doesn't really matter whether the charger trickle charges or not...the battery can't possibly be overcharged to anything greater than 4.24V. Is that right?


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## DM51 (Dec 5, 2007)

4.24V *is* overcharged. The extra 0.04V doesn't sound much, but it is another ~4% of energy that is being forced into the cell, and that will shorten its life because it is not designed to take it.

However, you say you have charger*s* (plural) that measure 4.24V. It sounds strange that more than 1 charger should register at precisely the same incorrect figure. Are you sure your DMM is reading correctly? 

If you can, ask an electrician or electronic engineer to calibrate it against his own instrument, which will probably be more accurate. If your DMM is off by as much as 0.05V, it is not really accurate enough for this sort of work.


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## mrQQ (Dec 5, 2007)

i just charged 2 18650's and 4 RCR123's which were just received from AW.. i measured them all about 5 hours later. all 4 RCR123's came out at 3.97-3.98v, 1 18650 was 4.02v, and 1 was 3.76v. I put that one into charger again, and 10 minutes later it was at 4.02v. 

so how come my charger doesnt put them to 4.2 like everyone's? and what's with that one undercharge?


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## Yenster (Dec 5, 2007)

DM51 said:


> 4.24V *is* overcharged. The extra 0.04V doesn't sound much, but it is another ~4% of energy that is being forced into the cell, and that will shorten its life because it is not designed to take it.
> 
> However, you say you have charger*s* (plural) that measure 4.24V. It sounds strange that more than 1 charger should register at precisely the same incorrect figure. Are you sure your DMM is reading correctly?
> 
> If you can, ask an electrician or electronic engineer to calibrate it against his own instrument, which will probably be more accurate. If your DMM is off by as much as 0.05V, it is not really accurate enough for this sort of work.


 
I agree that 4.24V is slightly overcharged...but at least it's under your 4.25V - 4.30V safe margin.

I actually have 5 chargers rated at 4.2V ... 1 @ 4.22V, 2 @ 4.23V, and 2 @ 4.24V...so they are all within tolerance. My DMM isn't a cheap one (Radio Shack 22-812), so I tend to believe it's the variations of those chargers and not that strange (I think it would be strange if all 4.2V chargers actually measured 4.20V).

However, my assumption is that a battery in a (measured) 4.24V charger will not charge over 4.24V even if left in there for weeks. Is that right, or is there something else that might cause further charging?


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## Yenster (Dec 5, 2007)

mrQQ said:


> i'm sorry for a stupid question, but since everyone keeps telling how dangerous LiIon is, i'll better be stupid than sorry  should wf-139 be making a "hiss" sound when charging batteries? the sound is in sync with red flashes - when they turn green for a split second the sound turns off, and comes back?


 
Interesting....is the WF-139 supposed to flash between red and green? I'm thinking that's not normal behavior and might be the cause of your undercharged batteries.


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## da.gee (Dec 5, 2007)

Mine flashes between red and green. I think this is normal.


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## Yenster (Dec 5, 2007)

The flashing seems odd. Has anyone monitored with a DMM to see if the voltage/current goes on/off with the flashing?

Also, what is the open voltage of the charger (without a battery in it)?


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## DM51 (Dec 5, 2007)

Yenster said:


> I agree that 4.24V is slightly overcharged...but at least it's under your 4.25V - 4.30V safe margin.





Yenster said:


> I actually have 5 chargers rated at 4.2V ... 1 @ 4.22V, 2 @ 4.23V, and 2 @ 4.24V...so they are all within tolerance. My DMM isn't a cheap one (Radio Shack 22-812), so I tend to believe it's the variations of those chargers and not that strange (I think it would be strange if all 4.2V chargers actually measured 4.20V).
> 
> However, my assumption is that a battery in a (measured) 4.24V charger will not charge over 4.24V even if left in there for weeks. Is that right, or is there something else that might cause further charging?


I failed to answer your question – my apologies.

If you apply a maximum of 4.24V to a cell, you are right in assuming that there is no way it can be charged to more than that voltage. It would however be very unwise to leave the cell on the charger for an extended time, especially as this would presumably entail leaving it there unattended. 

You say that 4.24V is “inside your 4.25-4.30V safety margin”. Please – this isn’t “my” safety margin! I have not set it! As far as I know, nobody has. It would be wrong to do that. It just happens to be the voltage at which some over-charge protection circuits are set to trip. Personally, I would prefer them to be set at 4.2V.

Please don't assume 4.25V-4.30V is 100% safe - there is no magic cut-off point between safe and unsafe (nothing in life is 100%). 4.2V is the correct maximum. 4.1V is safer than 4.2V. 4.3V is less safe. Etc, etc. If you want a “serious danger” figure, then I would say >4.4V, at which point you are looking at a very imminent nasty firework scenario. 

The effect of over-charging on the cycle life of Li-Ion cells is indicative. SilverFox is the CPF authority on all matters to do with batteries, and he posted a table some time ago in another thread, showing the number of cycles you get if you charge a Li-Ion cell to a given voltage:


Charging to 4.1 volts gives you >2000 cycles.​Charging to 4.2 volts gives you 500 cycles.
Charging to 4.3 volts gives you <100 cycles.
Charging to 4.4 volts gives you <5 cycles.

Your 4.25V figure would indicate that you might get ~200 cycles out of your cells – in other words, you would be drastically shortening their life.


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## Yenster (Dec 5, 2007)

Thanks DM51 for taking the time to explain.


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## mdocod (Dec 5, 2007)

> i just charged 2 18650's and 4 RCR123's which were just received from AW.. i measured them all about 5 hours later. all 4 RCR123's came out at 3.97-3.98v, 1 18650 was 4.02v, and 1 was 3.76v. I put that one into charger again, and 10 minutes later it was at 4.02v.
> 
> so how come my charger doesnt put them to 4.2 like everyone's? and what's with that one undercharge?-MrQQ



I have found that in some cases, what happens is, you pull off the charger, and the cell MEASURES ~4.00V, but then as soon as you put a temporary load on it, it spring up to the 4.20V that it is actually at... I have yet to figure out what causes this behavior, It only happens with my AW protected 18650 cells, and I think it has something to do with the protection circuit..

try putting those "~4.0V" cells into their device (flashlight or whatever), then turn it on for a second, pull the cells, and test again.


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## mrQQ (Dec 6, 2007)

i will do that, i just don't have any devices for them yet lol.

anywa, considering the hissing sound between flashes disappears, my guess would be that the voltage is cut aswell. and i just measured open voltage between contacts without battery inserted and it read 4.77 on both channels.


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## Yenster (Dec 6, 2007)

Thanks for the feedback mrQQ. So this charger outputs 4.77V and has the potential to overcharge if batteries are left in the charger.

I still don't quite understand the flashing from red to green to red again. I'm wondering if it only flashes when the battery gets close to fully charged, or, does it also flash when a drained battery is starting its charge.

I also have a DSD charger that has an output of 5.5V (5.94V measured). It will cut off the power completely when the light turns green so it doesn't seem to trickle charge.


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## mdocod (Dec 6, 2007)

most chargers "pulse" on and off and take voltage measurements of the cell with the charge "off." see.. it wouldn't get a very accurate reading of cell voltage of the charging was active at the time it takes the reading. So that's why it "flickers" back and forth. My Vanson Speedy box does the same thing with NIMH cells... the only charger I own that doesn't kick on and off like that is my intellipeak pulse pack charger for NIMH/NICD stuff.. It does things a little different, but is the best pack charger I've ever owned.


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## mrQQ (Dec 6, 2007)

well, it goes like this - i plug the charger to socket, and both channels light up green. i then put in battery, and the light turns to red, that red stays for a second, then for a split second it will flash to green, and back to red for another second, and so on so forth. and the hissing sound is in sync with red light. i'm not too worried, because AW kinda says that it's how it's supposed to work:

http://www.cpfmarketplace.com/mp/showthread.php?t=142521



> **The red LEDs will blink every few seconds when the Samsung IC checks the feedback voltage from the battery. In fact, it 'll check the feedback 3 times during every blink. It is the designed charging parameters of the charger and is perfectly normal.


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## Yenster (Dec 6, 2007)

That's interesting about the flashing. I guess my chargers don't do that...or maybe they do but the light just doesn't blink. I have the DSD, Nano (3.6), and another kind from DX (2x18650 4.2V 2x1A) and none of them blink. Well the DSD blinks when there's no battery in it, but it's solid red when charging and solid green when charged. My DMM doesn't seem to sense any voltage or current fluxuation during charging.

Thanks for the info.


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## Alan B (Dec 6, 2007)

My new WF-139 seems to end the charge at 4.28V.

May have to dig in and change the sense resistor. Anybody done that already on this unit?

-- Alan


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## mrQQ (Dec 6, 2007)

if you manage to figure out how to fix termination voltage, please do tell, because mine terminates at 4.05 

btw, to those who know - how much % of total capacity do i get at 4.05v?


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## ALWZWFO (Dec 6, 2007)

Mine terminates at 4.209 just after turning green with Tenergy 2600 protected.


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## SilverFox (Dec 7, 2007)

Hello Mdocod,



mdocod said:


> I have found that in some cases, what happens is, you pull off the charger, and the cell MEASURES ~4.00V, but then as soon as you put a temporary load on it, it spring up to the 4.20V that it is actually at... I have yet to figure out what causes this behavior, It only happens with my AW protected 18650 cells, and I think it has something to do with the protection circuit..
> 
> try putting those "~4.0V" cells into their device (flashlight or whatever), then turn it on for a second, pull the cells, and test again.



I have seen that happen when the over voltage protection circuit kicks in. 

Tom


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## mrQQ (Dec 9, 2007)

SilverFox said:


> Hello Mdocod,
> 
> 
> 
> ...


 
i tried putting them into flashlight, and they still came out at ~4.. so does that mean my charger is bugged? that would suck, cause shipping it back would cost more than whole charger + shipment cost me..


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## mrQQ (Dec 9, 2007)

i discharged one of them to 3.85, then put it into charger, and it still only charged them to 4.03 

seems i ended up with a dud charger and can do nothing about it


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## gravityz (Dec 9, 2007)

mrQQ said:


> i tried putting them into flashlight, and they still came out at ~4.. so does that mean my charger is bugged? that would suck, cause shipping it back would cost more than whole charger + shipment cost me..


 

i think that will be the problem of the company you bought it from

if they ship yuo a faulty piece then they will have to send you another one
they will also have to pay for shipment back
if this is more expensive than the charger itself i think they will tell you not to ship it.


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## mrQQ (Dec 9, 2007)

That company is AW..


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## gravityz (Dec 9, 2007)

is this only with the 18650 or also with others like 14500

personally i would not think this is a problem because batterylife is prolonged greatly at this voltage
cell would still be charged to around 95% i think

what if you leave it in the charger after the green light turns on

will voltage decline or will it slowly raise.


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## DM51 (Dec 9, 2007)

mrQQ, are you 100% sure your DMM is giving you accurate readings? Before doing anything else, I would suggest you check it against another meter. 

If your DMM proves to be accurate, then it sounds as if your charger is a faulty one. 

gravtyz, a Li-Ion with a resting voltage of 4.0V is ~80% full, not ~95%.

When a charger's light turns green, the cell should be removed straight away, NOT left there.


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## gravityz (Dec 9, 2007)

DM51 said:


> mrQQ, are you 100% sure your DMM is giving you accurate readings? Before doing anything else, I would suggest you check it against another meter.
> 
> If your DMM proves to be accurate, then it sounds as if your charger is a faulty one.
> 
> ...


 

thanks for correcting me

i only did an educated guess(which apparently ws not so educated)


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## mrQQ (Dec 9, 2007)

gravtyz said:


> is this only with the 18650 or also with others like 14500
> 
> personally i would not think this is a problem because batterylife is prolonged greatly at this voltage
> cell would still be charged to around 95% i think
> ...


 
it happens with RCR123's aswell.

i didnt try them leaving for very long, but half hour later they still read same 4.04 or so.


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## mrQQ (Dec 9, 2007)

DM51 said:


> mrQQ, are you 100% sure your DMM is giving you accurate readings? Before doing anything else, I would suggest you check it against another meter.
> 
> If your DMM proves to be accurate, then it sounds as if your charger is a faulty one.
> 
> ...


 
I rechecked them with analog multimeter, and it read same..

80% is a bit low.. if it was around 90% i probably wouldnt mind at all..


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## DM51 (Dec 9, 2007)

If this is happening with a number of cells and your multimeter(s) agree on the voltage, there is a fault with your charger. You should return it and ask for a replacement.


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## mrQQ (Dec 9, 2007)

I think we'll solve it with AW somehow  He seems to be a very cooperative and nice guy! =)


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## Rzr800 (Dec 9, 2007)

DM51 said:


> "...There appear to be inconsistencies in the manufacture of these units, with some giving different results to others. You seem to have a good one if it is not taking any cells above 4.20 volts.
> 
> Ultrafire have not released a new version of this charger AFAIK.


 
I have one light on the way with but one 18650 in it (my only li-ion light). If I keep track of the charging time with this unit; would it probably be my best buy for the buck using protected cells purchased with it? (and to sneak in another...would you choose the Maha MH-C9000 for my Eneloops; as has been generously suggested by another member?).


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## DM51 (Dec 9, 2007)

Rzr800 said:


> I have one light on the way with but one 18650 in it (my only li-ion light). If I keep track of the charging time with this unit; would it probably be my best buy for the buck using protected cells purchased with it?


The QC on these WF-139 chargers seems quite hit and miss. The majority of them are probably OK, but some of them overcharge, and a few (like mrQQ's one) seem to undercharge. 

The WF-139 is NOT recommended for use with UNprotected cellls, as it can continue trickle-charging after the light has gone green. At least with a protected cell, the protection will prevent gross over-charging and possible venting with flame. With an unprotected cell left on charge unsupervised, a nasty accident is very likely.

See what it does with your protected cell. Pull the cell off the charger as soon as the light goes green, leave it to rest for a while and then check the voltage. In all probability the charger will have terminated correctly at 4.2V (+/- 0.01V) and you will then know you have a good one. 

If on the other hand the voltage is high, despite taking the cell off charge promptly, it is likely to continue doing that.

Timing the charge is only a rough guide, as the duration of the charge will depend on the initial voltage of the cell.


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## Rzr800 (Dec 9, 2007)

DM51 said:


> "The majority of them are probably OK...See what it does with your protected cell. Pull the cell off the charger as soon as the light goes green, leave it to rest for a while and then check the voltage. In all probability the charger will have terminated correctly at 4.2V (+/- 0.01V) and you will then know you have a good one.
> ."


 
Thanks for the advice as I just can't beat the price or (evidently) service from this AW fellow and with only a few protected 18650's (at this time) to worry about..your assurance is very helpful in making this decision (probably spend the money saved here on the MH-C9000 for the Eneloops).


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## AW (Dec 10, 2007)

mrQQ,

A replacement charging unit has been shipped.

AW




mrQQ said:


> I think we'll solve it with AW somehow  He seems to be a very cooperative and nice guy! =)


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## mrQQ (Dec 10, 2007)

Amazing! I'm definitely going to order some more stuff from you!


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## gravityz (Dec 11, 2007)

Wow

really good support

i which i bought my charger also from AW

let us know what the end voltage on the new charger is.


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## nanoWatt (Dec 14, 2007)

Question,

Can I charge single 18650 cells with this charger? Or do I have to double them up? I will be needing a battery for a laser that uses a single, and need to know. This is the charger I have.


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## fa__ (Dec 14, 2007)

It's a two channel charger, like the wf138, so you can use one or two channels without difference


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## cernobila (Dec 14, 2007)

Well, might as well add my experience to this. My charger has been used to charge the C size cells and they all took different times to charge for the first time which is ok. After they came of they varied from 4.02 to 4.2. I placed the ones with less than 4.2 back in the charger after about 30 minutes rest to see what happens and they all came out between 4.19 to 4.22....I guess that this is within tolerances. My question is why do some trip the green light at 4.02 and others trip the green light at 4.2........


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## CallMeDave (Dec 22, 2007)

DM51 said:


> Good Li-Ion chargers terminate properly at ~4.2V, and do not rely on a cell's protection circuit.




So what are other high quality chargers besides the WF-139 that started this thread? 

I'm a non-technical user interested in getting into some of the new 18650 powered throwers, and would rather use a charger with known high quality control.


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## Rzr800 (Dec 22, 2007)

I was shipped a couple of what look like 9/16" stepped 'spacers' with (I believe) the 18650s (or maybe the WF-139 charger) and two tiny magnets with the two 14500s that I'm about to charge now. Does anyone know what these are for and if I have to use them in this charger? (the WF-139 was shipped with no instructions).

Thanks.


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## Alan B (Dec 22, 2007)

Rzr800 said:


> I was shipped a couple of what look like 9/16" stepped 'spacers' with (I believe) the 18650s (or maybe the WF-139 charger) and two tiny magnets with the two 14500s that I'm about to charge now. Does anyone know what these are for and if I have to use them in this charger? (the WF-139 was shipped with no instructions).
> 
> Thanks.


 
Those cylinders are to make short cells (such as RCR123 size) fit. The cross-wise terminals are not connected, so you need to use the longer slots and terminals. 

The tiny magnets are sometimes needed to make up for the flat end on some cells. Make certain they don't drift to the edge and possibly cause a short.

-- Alan


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## Rzr800 (Dec 22, 2007)

Thanks, Alan and a very Merry Christmas to you and yours.


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## DM51 (Dec 22, 2007)

CallMeDave said:


> So what are other high quality chargers besides the WF-139 that started this thread?


The Pila IBC charger is the best of the 2-bay 'automatic' chargers.


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## mrQQ (Jan 9, 2008)

i got a replacement and it works fine. great service!


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## Gatsby (Jan 9, 2008)

An interesting situation - the choice seems to be use the WF-139 and test it when the light turns green promptly to see if it is working and if so, make sure to monitor the charge and remove it promptly (something easy for me to do as I charge while sitting at my desk at work so as to keep an eye on things and remove cells from my Nano as soon as it goes green) or get the Pila IBC for a much more predictable result. I have to admit that the $18 shipped versus $49 plus shipping difference might make me inclined to monitor the charges with the WF-139 ... but I also keep asking myself what price for safety?


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## mrQQ (Jan 9, 2008)

actually, i've left 18650 in wf-139 for 8 hours after turning green, and it wasnt overcharged a bit.


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## nanoWatt (Jan 9, 2008)

Was it a protected cell?



mrQQ said:


> actually, i've left 18650 in wf-139 for 8 hours after turning green, and it wasnt overcharged a bit.


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## mrQQ (Jan 10, 2008)

yeah, AW..


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## fa__ (Jan 10, 2008)

So you tested the protection circuit, not the wf139


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## mrQQ (Jan 10, 2008)

well yeah, i guess you're right


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## gravityz (Jan 10, 2008)

i also tested this

with AW the batteryprotection circuit kicks in
voltage with a green light WHILE THE CELL IS STILL IN THE CHARGER IS 4.6 volts because the protction circuit is open


with trusfire the chargerprotection circuit kicks in
voltage with a green light WHILE THE CELL IS STILL IN THE CHARGER IS 4.20 volts because the it resembles the voltage of the cell

the $100 question would be
When will either the batteryprotection or the chargerprotection be reset.

i think regarding to AW the circuit is open but is still reading 4.6 volts on the clamps so it will not be closed until you take it out of the charger

regarding to trustfire. if the voltage drops below a certain point the charger might pick up again because it thinks the cell is not full anymore.

you can not test this because once it starts it will stop probably after a minute because the voltage is high enough again.
this behaviour can overcharge a cell


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## pbs357 (Mar 4, 2008)

I tested 4 unprotected rcr123's in a DSD charger and my new WF-139. I bought the WF because of the independent channel charging, and also I've read that the DSD doesn't fully charge the cells.

All 4 cells were between 3.81v-3.85v. After a little less than an hour, I checked both chargers and all lights were green. Interestingly, all 4 cells read 4.12v-4.14v, none of them at a full 4.2v but both reaching "green light" at the same time. Another observation is that the WF charged cells were very warm, while the DSD charged cells were cool. At initial charging, the WF made an electronic buzz, almost like a hissing noise. Just wondering if I really "upgraded" by buying this?


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## fxstsb (Mar 4, 2008)

pbs357 said:


> I tested 4 unprotected rcr123's in a DSD charger and my new WF-139. I bought the WF because of the independent channel charging, and also I've read that the DSD doesn't fully charge the cells.
> 
> All 4 cells were between 3.81v-3.85v. After a little less than an hour, I checked both chargers and all lights were green. Interestingly, all 4 cells read 4.12v-4.14v, none of them at a full 4.2v but both reaching "green light" at the same time. Another observation is that the WF charged cells were very warm, while the DSD charged cells were cool. At initial charging, the WF made an electronic buzz, almost like a hissing noise. Just wondering if I really "upgraded" by buying this?


Hi, what was the current rating of the batteries?


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## fxstsb (Mar 4, 2008)

DM51 said:


> The QC on these WF-139 chargers seems quite hit and miss. The majority of them are probably OK, but some of them overcharge, and a few (like mrQQ's one) seem to undercharge.
> 
> The WF-139 is NOT recommended for use with UNprotected cellls, as it can continue trickle-charging after the light has gone green. At least with a protected cell, the protection will prevent gross over-charging and possible venting with flame. With an unprotected cell left on charge unsupervised, a nasty accident is very likely.
> 
> ...


So is this the answer to PBS357s question? After the light goes green it trickles. After a few hours is it 4.2 volts?


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## Black Rose (Aug 12, 2008)

I am contemplating jumping into the world of CR123 lights and was considering getting the WF-139 charger (modding it to use the 123 bays) and charging AW RCR123s in it.

Is there any way to determine if a WF-139 charger is one of the "OK" ones vs one that will overcharge?


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## DM51 (Aug 12, 2008)

You wouldn't need to mod it - just make 2 spacers so the RCR123s cells fit in the longer bays, or buy 2 of AW's dummy 123-size cells, which will do the same thing.

The best way to avoid over-charging problems with the WF-139 is to watch over it throughout the charge and pull the cells immediately the light goes green. 

My recommendation would be for you to invest in a Pila IBC, which is a better charger all round.


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## Black Rose (Aug 12, 2008)

DM51 said:


> My recommendation would be for you to invest in a Pila IBC, which is a better charger all round.


According to a post by the admin of the board at flashlightZ, Pila does not recommend using the IBC charger for RCR123 cells.

Probably just a CYA measure by them, but still...


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## DM51 (Aug 12, 2008)

As you suggest, I think there is a bit of &$$-covering there.

AW's RCR123s are rated at 750mAh (under a heavy load, they would achieve about 600mAh).

The Pila IBC output per bay is 600mA, so the charge rate would not exceed 1C and is therefore perfectly OK.


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## Black Rose (Aug 13, 2008)

Based on mdocod's thread about the WF-139, I'm going to hold off on this one and wait until I have enough $$$ to get the Pila IBC.

I invested a fair amount of money in Maha chargers for my NiMh cells, I think it's better to do the same for Li-Ion cells.


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