Output from WF-139

Batteries and Chargers Chargers
1

A post by kramer5150 in another thread regarding the output of a charger, made me measure my UltraFire WF-139... why does my DMM show ~5.32v instead of ~4.32v ???

2

Out of curiosity, I just checked my uf wf-139 and it shows 5.37v. What's up with that?

3

lol so I am not the only one...

4

You're definitely not the only one. I'm going to check my other chargers.

5

I have 2 WF-139's. The older of the 2, the one that I had to mod to accept the longer protected cells has an open circuit voltage of 5.13. The newer of the 2, the latest revision that accepts the longer cells, has an open circuit voltage of 4.23. Both of these chargers charge to exactly 4.2V

6

Here's my other chargers:

TF TR-001 = 4.23v

Pila IBC = 4.13v

Something must be wrong with our UltraFire WF-139's.

7

So thank god our batteries didn't explode while charging???

Anyone else with a wf-139???

8

The chargers start out in constant current mode.

This constant current won't cause your cells to explode.

9

nothing wrong with it, just try to charge a battery and check its voltage

10

Batteries charge fine, I was just wondering if the charger operates at a higher voltage if this is damaging the batteries... other chargers from what it seems, work at 4.2v as expected.

11

higher open circuit voltage doesn't mean automatically that it will overcharge the cells, mine wf-139 has 5.36V oc voltage, and charges the cells to 4.20V

12

I'll give it a try.

13

How do you measure the out output from a charger? I've been using my WF-139 for about a year now with no problems of over charging. But one bay does charge faster then the other.