Which Charger Should I Use ?

[Bob96]

I own two chargers. I use the Ultrafire WF-138 for my RCR123's. My other is a Ultrafire WF-139 I use for 18650 batterys. Looking at the spec. labels on the back of the units the 138 supplies 3.60 V at 250 mHa and the 139 suppplies 4.2 V at 450 mAh. Both the 123 & 18650 batterys are rated at 3.7 V and supposed to come off the charger at 4.20 V. Does this mean that my 123"s charged on the WF-138 unit are not up to capacity as the green light I guess comes on at 3.6V ?
I have ordered some AW IMR 123 cells and some 15mm spacers that allow the 123 size to be charged in the WR-139 unit. Am I better off in getting maximum performance to charge my 123 size cells using the spacers in the WF-139 and having the green come on at 4.20V ?
The WF-138 also has a 3.0V switch but I use the 3.6V setting.I wonder why this unit uses lower voltage to charge the cells ?

 

[Mr Happy]

What is written on the back of a charger can sometimes be misleading. It is better to refer to the operating instructions that come with the charger. Both chargers should be charging to a nominal 4.2 V.

Also, are you using Li-ion cells without using a voltmeter to check the voltage off the charger and before charging them?

 

[45/70]

It pretty much boils down to what our Chinese friends feel like printing on the backs of their chargers, Bob.

LiCo and LiMn Li-Ion cells are 3.6-3.7 Volt cells, nominally, or under a load. The open circuit (OC) voltage is 4.2 Volts for these two chemistries.

The "3 Volt" setting on your WF-138, is for charging LiFe Li-Ion cells. LiFe cells are 3.0 Volts nominally (actually closer to 3.2-3.3 Volts, but anyway), and 3.6 Volts OC off the charger.

And, Mr H has a good point. You should be using a Volt meter to check these types of cells, before trying to charge them. This can help to avoid problems down the road.

Dave