Running tests on the WF-139. Interesting results. A must read for WF-139 users.

[15miki15]

Is WF-139 charging method good? Or it is destroying faster that "classic" method lowering current (no CC/CV)? Iam thinking to buy it. I do not plan spending a lot of money for Pila charger.

 

[old4570]

There is no evidence the WF-139 damages cells ..
If you buy a cheap charger , and cheap nasty batteries , and the cheap nasty batteries fail or degrade ?? Do you blame the charger , or the cheap nasty cells .

All chargers are some what safe when monitored ...

I just tested a charger that fried itself after charging one battery , not what I would call a safe charger .... The WF-139 does the job , and it does it well for the price you pay ...

 

[David Cameron]

I just received my WF-139. With no battery in a slot the reading is 4.25 V on each slot. When an almost fully charged battery(3.99 V) type 18650 is put in the slot the reading is 4.01 V. This charger for all intensive purposes charges to 4.2 V. People who have posted seem overly concerned about the last .05 V without taking into account the internal resistance of the battery. This resistance is overcome by charging voltage being higher than target battery voltage. This is not a sophisticated multistage charger but it does appear to safely charge the 18650 cell. There is no such thing as constant current AND constant voltage charging. Either voltage is varied to maintain a constant current through the varying resistance of the battery or the voltage is held constant and the current varies as the battery internal resistance varies. I prefer constant voltage with a current limiter

 

[DM51]

I prefer...

To those who ask how it is possible for someone to run a country and still find time to try and sound knowledgeable about battery charging, my usual response is "It is not easy at all."

 

[Mr Happy]

There is no such thing as constant current AND constant voltage charging.

There is such a thing as constant current OR constant voltage however, which is what a CC/CV control algorithm is supposed to do.

 

[45/70]

......This is not a sophisticated multistage charger but it does appear to safely charge the 18650 cell. There is no such thing as constant current AND constant voltage charging

This is why a charger that utilizes a two stage process is prefered (from Battery University). The first stage is CC and when the circuit voltage reaches 4.20 Volts, in the case of a LiCo cell, stage 2 begins, which is the CV stage. A charger which utilizes these two stages therefore is in effect, a constant current and constant voltage charger.

Dave

 

[tandem]

To those who ask how it is possible for someone to run a country and still find time to try and sound knowledgeable about battery charging, my usual response is "It is not easy at all."

LOL!

We should all be pleased to see the current Prime Minister of the United Kingdom, David Cameron, stop in to chat about a cheap sub-optimal charger. Who knew?!

 

[DM51]

LOL!

We should all be pleased to see the current Prime Minister of the United Kingdom, David Cameron, stop in to chat about a cheap sub-optimal charger. Who knew?!

In fact, this sort of thing happens quite frequently.

 

[ElectronGuru]

Is WF-139 charging method good? Or it is destroying faster that "classic" method lowering current (no CC/CV)?

There's a table somewhere showing a list of different max charge voltages and their corresponding lifespans (number of charges). Lower the top voltage -> less stress on the cell -> more charges before the cell declines. More time before the cells need replacement.

I think of CC vs CC/CV the same way. CC/CV is more gentle, but costs more, so get the charger that corresponds with the value of your battery stash. If you have $35 in cells (a couple of 18500's), a $20 charger makes sense. Another $35 in x years, not a big deal. $180 worth of cells (10x 2900's) changes things a bit.

 

[Alpinebully]

I just received an Ultrafire WF-139 Charger, bundled with a 2X Ultrafire BRC 18650 3000mAh and a new 2nd Generation Fenix TK35.

My brief testing of the WF-139 Charger ive received shows:

The Open Circuit / OC for the charger is 0 Volts.

Installing moderately discharged batteries results in a charge of 0.330A being fed into the batteries. The voltage at completion is 4.17Volts.

It does not trickle charge at the end of charging and the LED indicators function as follows; Power On with no Cells installed = Solid Green. Discharged Cells installed = Red, blinks to Green every 1.5-2 seconds. After Charging has completed = Solid Green.

 

[Alpinebully]

Sorry, just a little further information to add to my post above;

Im not sure about the CC/CV thing... not sure what my charger is doing.

It seems like it is immediately going into a CC cycle. Install cell, current is constantly floating between 0.330-0.335A. The voltage simply slowly rises until the LED's go Solid Green. At which point the Cell voltage is 4.17V.

I havent been able to find much information online at all about this Open Circuit = 0V 'Generation' WF-139. The one and only reference i found to it, suggested it having a higher charge rate around 1-1.5Amps. Clearly mine does not.

 

[razvan-l]

HELLO !
iam new here end i say hello to all mebers.
a received today a last version of a WF_139 , and the open circuit voltage is 4,25 volt
after complete test will post the measurement
sorry for my bad english
razvan
if you request i atach the foto with pcb