WF-139 How long to turn green

[bullpup]

Please help. I just plugged in my dx charger with unprotected batteries. When should I check to see if green? Any idea how many hours aprox? I feel funny falling asleep while possible overcharging. THe battery's are ultrafire 14500 900 MA they are fresh from the package and it is the first charge ever. TIA

 

[mdocod]

depends on cell size, depends on how drained they are.

give more info!, lol.

 

[AlgaeEater]

Just got mine from Lighthound today and have been charging since I got home.

All I know is for 14500 AA cells, it takes about an hour. I basically just have the charger right in front of my computer so I can keep an eye on it at all times. Once it hits green solid I take it out.

 

[nickz]

Personally I never sleep while charging Lithium Ions. I have done it once by accident with my dsd and an unprotected 18650 but that was a puckering experience when I realized what I had done the next day.

 

[bullpup]

To answer it turned green in about 1 1/2 hours maybe even closer to 1:15. A lot quicker then I would have thought

 

[AlgaeEater]

To to answer it turned green in about 1 1/2 hours maybe even closer to 1:15. A lot quicker then I would have thought

It's an agressive charger, 450ma @ 4.2V. That's why I'm scared to leave anything in there. But yeah, I get about an hour until green like I said on my first post.

 

[bullpup]

I think I better buy some protected 14500 my next problem is runnning them to low!!!

 

[cfromc]

My unprotected 18650s (2400mAh) take a lot longer than an hour, in fact, I think its closer to 3+ hours when they are low, but, every time I've charged them they've come out to an exact 4.20V so I'm not complaining.

 

[HarveyRich]

My experience has been that you need to take the battery out well before the charger reads solid green if you want the voltage to be at 4.2v. If you let it go to solid green you'll likely have 4.3+v on the battery, which is over the limit. It's pretty annoying because you have to pay attention and can't forget about the charging process. I've been thinking of looking for other than Ultrafire chargers because of this.

 

[doc_felixander]

oh well....my efforts to add an overcharging protection IC failed.
It should have terminated at 4,25V (TI UCC3952-1), but it still went up to 4,40V. This sucks.
I really like this charger because it takes any cell size I have lying around here, but I think it definitely NEEDS a new circuit.

 

[DM51]

4.4v is really bad. Cell life is dramatically reduced (Silverfox reports down to only ~4 cycles) and it in serious danger of blowing.

 

[doc_felixander]

yup, I marked that cell and I'll watch how it behaves in the next few cycles.

I must add that the cell must have been sitting in there for a few hours before I removed it, I can't really tell how long the charger has been trickling. Unfortunately I didn't measure the voltage when the LED turned green.

It seems the Texas protection IC can't cope with the pulsed current during trickle charge.

Would be interesting if it causes venting after some time, and how long it would take.
If I manage to build a box that can handle a bursting cell, I'll do a test run.

 

[AlgaeEater]

I think all Ultrafire chargers have trickle-charge problems. I know it's not 100% the safest way to ensure overcharging by just pulling the batteries the moment it turns green, but it helps take out a lot more risk than leaving it in.

I don't know what to say really, Li-on's are tricky batteries. Sometimes I just charge 30-60 minutes and then yank them out and measure the voltage. If it's above 4.1, I consider it charged enough, even if the battery isn't topped off.

 

[Effulgence]

I've noticed that when using AW Protected 14500s 750mA (brand new from lighthound), the charger is blinking every so often - this is normal, but it also produces a hissing sound. AW 14500s have overcharge and overdischarge protection, so this thing does have vents, which is why I'm cautious right now. The Tenergy charger I got from BatteryJunction.com (looks just like the DSD) doesn't result in this hissing. I swapped batteries around (I have 9 of these) and between the WF-139 (I have 2) and it still produces the hissing (only on charging cells).

I'm wondering if this hiss sound is a dangerous indicator and if these cells are itching for an explosion. Anyone have this 'problem' too or is this perfectly normal?

 

[AW]

Effulgence,

Are you sure the ' hissing ' noise is from the batteries ? Not from the charger electronics.

AW

 

[doc_felixander]

If you're using the AC input, it's most probably the internal switching power supply.

 

[the servents of twilight]

I have been using mine with DX unprotected 14500s. I have had no problems so far. I have been taking them out when light turns green, and they have been under 4.2v every time.

 

[Effulgence]

Sorry If I came off sounding like a bash, I didn't intent it to be. It's just that I have 2 WF-139s and 9 AW 14500s and that hiss noise is a little odd... Only the charging cells do this, I'm in the U.S. and am using a wall outlet to plug the charger in (AC I believe).

I ask because I don't know if it is the cells or the charger electronics.

Edit: (BTW, these WF-139s came from DX)

 

[jumpstat]

My experience with unprotected cells is that once it hits 4.4v chuck it away. I killed 2 600ma 16340. Its my fault really since I used an RC charger......