I just recieved a brand new Solarforce protected 3.7v 16340 in the mail today and as i normaly do, checked the Voltage before throwing it on the charger and I get 0.00... Whiskey Tango Foxtrot? I have never had this happen before.
I did... all I get is a green light (Ultrafire WF-139) it doesn't start charging at all.
Hi Light. Some chargers are incapable of resetting the protection circuit. What you might try, and there is a bit of risk here, is parallel the Solarforce cell with another "good" cell for one second, or less.
If you attempt to do this, do so in a safe environment and only parallel the cells for one second, no longer. Usually, this will reset the protection circuit, if that is the problem. Check the voltage of the cell afterwards, if it is ~3.00 Volts or so, the cell should then charge normally on your WF-139. If there is no voltage after paralleling the cell with a good cell, the Solarforce cell is likely damaged, or defective. If the voltage comes up, but not to around 3 Volts or more, I would abandon the effort, as the cell has been over discharged.
A good way to parallel the cell with a good one, is to hold both cells on the edge of a metal kitchen sink, positive (nipple) side down, and bridge a table fork across the bottom (negative) ends. Again, do not parallel the cells for more than one second maximum, or you may run into trouble.
Also, cells that are reset in this way should be monitored closely when charging, for several cycles. If you notice the cell is warmer than normal when charging (if it gets "hot" stop charging!), does not hold a charge well, or any other anomalies, discard/recycle the cell, as this is a sign that the cell has been damaged.
And last but not least, try this at your own risk! The chances of something bad happening are minimal, but......
Hey thanks 45/70, I tried it and it worked. I had no idea about this. I now only get a volt reading of 2.6 though, so I guess this cell is no good. Well I learned something new and Solarforce-sales said they would send me another so I'll just chalk it up to a learning experience and another reminder how great CPF is.
Yeah Light, it's best not to take a chance. That's great that they are sending you a replacement.
I maybe should have mentioned why I like the kitchen sink/fork method for paralleling cells. Stainless steel is a relatively poor conductor of electricity, for a metal anyway. If you set the cells on the edge of a SS sink, or the SS strip that surrounds many other types of sinks, and then use a SS fork, you in effect reduce the inrush current when you parallel the cells. It's probably not a big deal, but I think it's probably a bit safer than using 4 gauge copper jumper cables, for example!
45/70, I have had this (0.0v pcb off) happen with brand new batteries and batteries that where discharged down to low voltage cut off point. Sometimes when discharged down to cut off voltage it seems they hang up turned off. The Wf-139 or my hobby charger has always set them back on. My question, is it that some chargers are reading this as a bad cell and want apply any voltage to the cell to turn the pcb back on? Or is it the larger current with the voltage that turns the pcb back on?
My question, is it that some chargers are reading this as a bad cell and want apply any voltage to the cell to turn the pcb back on? Or is it the larger current with the voltage that turns the pcb back on?
Hi mod. I think the answer to to your question may be, both. It depends not only on the charger, but what version of the charger, as well.
As far as I know what actually resets the PCB is a very short in duration, voltage spike. Chargers that do not employ this brief spike (which may be incorporated either by design, or is accidental) are the ones that are incapable of resetting the PCB. When paralleling two cells together, this creates a similar spike, and thus resets the PCB.
Chargers that read a cell in which the PCB has tripped, as a "bad" cell, are a different story. I believe most of these chargers however, will only reject cells that are low in voltage, eg. some value above 0.00 and below ~2.50 Volts, but will still reset a cell that reads zero. I'm not sure about that though.
45/70 thanks for the reply. What you have described seems about spot on to me. I know that my hobby charger will detect a bad low voltage cell without question. It will not charge a low voltage cell at all if its out of spec. So there must be some sort of voltage spike it sends before testing the cell. Because it will reset the pcb with no problem. As for WF-139, they change the circuits and components around so much that this feature could be in some or left out. Mine will reset the pcb as far as what I have tested so far. It could also be that the pcb needs so much voltage or current to turn itself back on. And there are differences in pcb's from battery pcb manufactures.
Perhaps my charger is out of date, but this trick from 45/70 just got two sets of 16340's charging again. Despite a few different attempts to get the battery charger to go into the "red" light mode, all I could get was the slow trickle or no charge "green" light. I used a steak knife for the positive terminals, two forks to bridge the negative terminals and an 18650 battery that was charged and left to rest several months ago to perform 45/70's trick. I put the cells back in the charger, plugged it in and the red light is on! I'll check the voltage tomorrow.