UltraFire WF-139 overcharges batteries? other option?

[stockae92]

i have read that the UltraFire Model: WF-139 overcharges batteries to up to 4.3V, which will shorten the life span of the batteries

what other charger option out there that can charge 18650 and RCR123 with auto top off without overcharging?

overcharging is equally bad for both protected and unprotected batteries?

 

[mdocod]

it will only over charge your cells if you let it.

 

[TITAN1833]

take batts of charge when light turns green. and they will not be over charged!

and leave them to settle a wee while before using.

 

[ampdude]

The WF-139 overcharges the batteries only in the sense that you leave them in the charger for an extended period after the light turns green.

It gives them a "full" charge to 4.25V like it's supposed to do and does a very good job of it. At least mine does. It does not charge at the advertised 450mA though, more like 300mA as others have observed. This is not a big deal though for such a versatile charger. Hopefully the charging current will be improved in a future version.

 

[mudman cj]

I actually prefer the cheaper DSD charger because it doesn't have the annoying sliding contacts that hang up and make it difficult to adjust for inserting an 18650 and it doesn't overcharge. The drawback is that the DSD requires spacers to charge 50 mm long cells, but I use them as well with no complaints.

 

[JimmyME]

Mine overcharges. If anyone thinks it doesn't, I'd be happy to trade with you.


If I take my batteries out as soon as the light turns green, they are 4.3 volts +

 

[JimmyME]

A follow-up:


I've thrown my WF-139 in the garbage and ordered a PILA IBC charger. I did this since my WF-139 is clearly overcharging and I don't want to take any chances with lithium cells.

I contacted the vendor who sold me the WF-139 but there was no effort to replace it. To me safety is more important than haggling over a $12 charger.

 

[mdocod]

maybe there's some duds in the bunch. I pull cells when they go green and have never seen higher than 4.201V. Usually it goes green at about 4.18.

[EDIT IN] I am editing this post from awhile back to point out that I have noticed that DURING the charge (while light is still red) the cell voltage actually rises to around 4.3V... then settles to around 4.20.... more on this in a later response...

 

[stockae92]

so some do overcharge and some don't??

 

[TITAN1833]

So out of the 2 i have, maybe one over charges and one wont.must get a battery for my multi meter soon and test.

 

[mudman cj]

I have read that they seem to overcharge unprotected cells more than protected. Mine charges AW protected 18650s and Ultrafire protected 18650s to 4.20 V. I haven't tried RCR123 or unprotected cells.

 

[mdocod]

hmmm, the protection theory seems plausible, all my cells are protected.

 

[stockae92]

so charging protected cells should be fine [without overcharging]?

where did you guys get your UltraFire WF-139 from? are they not all equal?

 

[AndyTiedye]

"Won't overcharge if we take it off as soon as it turns green" isn 't really good enough.
How often are we expected to check this thing?

It should TURN OFF when the battery is charged.

 

[hank]

It's time to make a little circuit:
Photodiode notices when LED turns green
Sends power to solenoid
Yanks cord out of wall
With a backup circuit:
Photodiode notices when infrared temp exceeds 451 degrees F
Sends power to solenoid 2
Discharges fire extinguisher aimed at charger.

That's basic safety. People can't just sit watching for a little light to come on to remove power from a device that's going to be dangerous if they don't.

That's what went wrong at Chernobyl, remember? (wry grin).

Seriously --- this is why the Underwriters Laboratories tests devices.

No matter how smart you are, and how careful --- some day, the device is going to be picked up by someone else, maybe out of your garbage can, and tried out by someone less well informed or less careful.

If it's bad enough to throw in the trash, hit it with a big rock first, and send the parts to the electronics recycler, eh? There's someone picking up used and dead electronics now in most major cities free, just to keep the stuff out of the landfills.

 

[nickz]

I agree. I was charging an AW unprotected 18650 the other evening in my dsd charger. I have a cold so I took some nyquill and started watching tv. Woke up next morning, went to work and about 9 am stood up and said "oh sh*t!" Got home from work at 9:05 am and pulled cell from charger and cell sat at 4.21v on my multimeter ! I got lucky that time! 16 hours on charge!!

 

[rdh226]

"Won't overcharge if we take it off as soon as it turns green" isn 't really good enough.
How often are we expected to check this thing?

It should TURN OFF when the battery is charged.

Hearing the same thing, I ran an experiment, I charged up a pair of AW 18650s, one on each of two
chargers; both turned green; left them sitting there for a good 6 hours, pulled and both batteries
were in the 4.17-4.19V range, same as when I pull them as soon as the LEDs go green. I have a
third WF-139 that tends to go 4.16-4.18V rather than 4.17-4.21V.

I have a vague theory that 14500's tend to come off at a higher voltage (4.2-4.23V) than my 18650s,
but this theory isn't even half baked yet.

I also have not correllated to room temperature (62F vs 66F let alone summer's 80F).

It is NOT line voltage variations as I run off a Furman regulator that holds 119-120V AC.

I really like the little WF-139 chargers, they're slow (read: "gentle"), sample of three behave nicely, they
run off of either 120VAC or 12VDC, and they handle everything from 14500 -18650s with aplomb
AND NO SILLY LITTLE SPACERS to get lost.

Granted, they are no Tritons, but I can buy five or six of the WF139s for the price of one Triton on
special closeout sale, and I can NOT misprogram the WF139 to overcharge a LiIon cell.

I do wish I could set them to run 4.1V program rather than 4.2V.

I bought my WF-139s from AW, for what that's worth.

And I will further opine that people who say "mine went to 4.203V -- that is unacceptable" and who
cannot qualify that with an "on my calibrated Fluke DVM" are engaging in mental masturbation.

-RDH

 

[stockae92]

I agree. I was charging an AW unprotected 18650 the other evening in my dsd charger. I have a cold so I took some nyquill and started watching tv. Woke up next morning, went to work and about 9 am stood up and said "oh sh*t!" Got home from work at 9:05 am and pulled cell from charger and cell sat at 4.21v on my multimeter ! I got lucky that time! 16 hours on charge!!

wait a sec, so both ultrafire and DSD chargers won't turn off automatically when the battery is fully charged? they will only turn the LED to green or something and keep on charging? they would at least reduce the charging current to very low level, right?

 

[gunga]

I have an WF-139 and have read a few things. Once the light turns green the charger chages to a trickle charge mode. It does a periodic test I believe and continues to slowly trickle charge. If you leave it a few hours, you can overcharge your unprotected cells. To my knowledhe, there shouldn't be problems with protected ones (since they are protected againts overcharging) but it's still a good idea to take the cells out once the light turns green.

No idea about the dsd...

 

[mudman cj]

The DSD terminates charging when the light goes green - no trickle.