WF-139 not able to charge 2 cells at a time?

[jsholli]

After doing several searches, I decided just to post this...please forgive me if it has been covered or otherwise beaten to death:

Has anyone found that their WF-139 charger will only charge one cell at a time? I have had my new wf-139 about 6 months and have charged about 3 pairs of ultrafire 3000mah cells...after a long period of use, I started to recharge another pair out of my M1X. The cells were down to about 3.5v each and both will charge separately in either bay, but not together. [when both cells are put in, the charger holds green for about 1 sec and blinks to red for about 0.3 sec...not red for a sec with a fast blink of green as before]

Has anyone else experienced this problem or heard of it [or how to address it]?

Thank you,
John

 

[jsholli]

Well...I guess that I answered my own question tonight; and, I doubt that anyone out there has had quite the same issue.

I noticed from the first charge cycle that the charger got warm at the upper top and bottom of the charger, so I added my own makeshift heat-sinks with some extra Neo magnets that I had lying around the house. I put a rectangle on the back and several washer types on the front...this was the cause of my problem of not being able to charge two cells at once. I removed and added the magnets a few times and was able to cause and remove the fault.

I guess the moral of the story is to beware of strong magnets...I didn't notice any adverse effects when using just one as a spacer, but 15 at once is a different story!

 

[march.brown]

Most chargers get warm at least during the first part of the charge when there is maximum current ... They shouldn't get too hot to hold ... Are you saying that you put magnets on the plastic to act as a sort of heat-sink ?

Covering the plastic with magnets might prevent the plastic from losing the heat normally ... If you are worried about too much heat, you could always dismantle the charger and drill holes (air vents) in the plastic top and bottom casing where the heat is worst.

I stand my chargers where they can get a good air flow underneath them as most of them don't have any cooling vents ... I put something under one end to lift it about an inch or so ... This does get rid of some of the waste heat better than laying the charger flat on the desk.
.

 

[jsholli]

Yes, I put one tall, thin one on the back and a column of round washer types on the front to pull the heat from the plastic and to prop the charger up off the counter top. They seemed to work quite well as simple heat sinks, but they were indeed the cause of my dual charging problems.

I've got some extra computer case fans lying around that may eventually get incorporated with this charger...it doesn't get too hot to touch, just warm enough make me think that it should be improved upon.