XTAR WP2 II ...not impressed.
- Thread starter Johann
- Start date
Help Support Candle Power Flashlight Forum
I just bought a WP2 II myself after coming to the conclusion that it's the best charger for the price. It can be had for $16, which is just a little more than the inferior WF-139.
Here's a full review from HKJ, which helped me tremendously in my decision
http://lygte-info.dk/review/Review%20Charger%20Xtar%20WP2%20II%20UK.html
Here's a full review from HKJ, which helped me tremendously in my decision
http://lygte-info.dk/review/Review%20Charger%20Xtar%20WP2%20II%20UK.html
Actually, the manual specifies 4.2±0.05V...see photo below.
I put the same Panasonic battery in an old DSD charger and as soon as the light went green the voltage measured 4.199V.
Then I tried an Ultrafire in the XTAR and it measured even lower @ 4.165V.
All XTAR charges where done in "1" Gear.
What accuracy is your Fluke DMM rated at?
To get the cell to hold and measure 4.2V after removing from charger, the cut-off voltage would have to be higher than the manufacturer specified 4.2V, or the cut-off current would have to be lower, much lower, a few hours of trickle charging at 4.2V might make the cell show near 4.2V on a multimeter. Again this is overcharging the battery since the charge goes on longer than manufacturer specifications.
it is possible that some batteries with extremely low internal resistance will actually show 4.2V when they come off charger that followed a proper charge algorithm, but this is rare, and we don't really use those kinds of cells in flashlights. By extremely low I mean in the order of 10mΩ for a 1000mAh cell.
it is possible that some batteries with extremely low internal resistance will actually show 4.2V when they come off charger that followed a proper charge algorithm, but this is rare, and we don't really use those kinds of cells in flashlights. By extremely low I mean in the order of 10mΩ for a 1000mAh cell.
jasonck08
Flashlight Enthusiast
It's a common misconception that a charger should charge a cell to 4.20v. As others have mentioned, this is not the case. The charger should have a 4.20+/- 0.05v CV stage. Depending on the cells age, internal resistance and cutoff current, the cell could come off the charger anywhere between about the 4.1v - 4.2v range (resting voltage after 1 hour). 4.17v is about perfect considering that it probably has about a 4.20v CV stage and then the voltage drops about .03v shortly after it terminates.
Some individuals choose to charge with a 4.1v CV stage to increase cell cycle life.
Some individuals choose to charge with a 4.1v CV stage to increase cell cycle life.
Yes, this is true in one sense. If the OP hasn't understood the truth after many great explanations then that would be unfortunate. However, this thread is very likely benefitting the many people out there that have the same misconception/misunderstanding of li-ion charge voltage. A lot of well explained and informed replies here.
G.D. Wolfie
Newly Enlightened
- Joined
- Feb 10, 2012
- Messages
- 2
Agreed, a great threat to shed light on some common misconception.
Gentlemen it's about perception. If my vehicle spec has a 20 gallon tank but mine only holds 19 then I feel cheated. How many of us buy the highest capacity batteries knowing full well that we'll never need a 20 hour runtime in a dark cave? Now if the item said you get 20 units of whatever and it actually holds 21, hey thats great, I got something better than the rest. How many rants have we had over 3.6v or 3.7v with that in mind anything over 4.0v should be extra. My bits of wisdom from a senile old man who spent too much on the latest and the best when last years model was half price.
I just charger Panasonic NCR18650A (3100mAh)unprotected with hobby charger. First with fast charge program (just 0.5A CC, no CV, end voltage 4.2V). OCV was 4.14V after charge. Then I charge it again with normal program( 0.5A CC, 4.2V CV and CV end current was 0.1A). Normal program charges 35mAh more and OCV was 4.19V. Difference was smaler than I expect.
.
Mr Happy
Flashlight Enthusiast
I just charger Panasonic NCR18650A (3100mAh)unprotected with hobby charger. First with fast charge program (just 0.5A CC, no CV, end voltage 4.2V). OCV was 4.14V after charge. Then I charge it again with normal program( 0.5A CC, 4.2V CV and CV end current was 0.1A). Normal program charges 35mAh more and OCV was 4.19V. Difference was smaler than I expect
But keep in mind you were using quite a low charging current. If you repeated the test using, say, 1.0 A or 1.5 A as the CC current the difference would be larger.
HKJ
Flashaholic
45/70
Flashlight Enthusiast
I guess this "LiCo cells should be charged to 4.20 Volts" myth will never go away. This discussion comes up over and over again.
It's really fairly simple. As far as I know, there is no specified voltage for which any Li-Ion cell should reside at, when fully charged and taken off the charger. The only specification is the maximum voltage of the charging circuit during the CV stage of the charge. For most LiCo and LiMn chemistry Li-Ion cells, this is 4.20 Volts +/- 1%, or 4.20 Volts +/- 0.05 Volt.
When a cell is removed from the charger, the cell voltage will decline, to some degree, depending on the age of the cell, it's use history, actual ingredients and compoents used in the cell (which varies from manufacturer to manufacturer), and so on.
I think part of the problem may be confusion between the terms "charging voltage" and "charged cell voltage". These are two different terms and are not really directly related to each other. As a result of the CC/CV charging process however, a cell will be limited to a voltage which is equal to, or less than the CV voltage of the charger. It will never be higher.
It alarms me that many strive to charge their LiCo, or LiMn cells so that, after charging, they read 4.20 Volts off the charger. Some have even gone so far as to modify chargers (usually inexpensive ones that don't use a proper charging algorithm to start with) so a voltage reading after removal from the charger of 4.20 Volts can be obtained.
This modification is potentially damaging to cells, and IMO, a dangerous practice. The older, or more used a Li-Ion cell is, the more likely it is to become unstable. The worst thing you can do to an old, or unstable cell, is to charge it to a higher voltage than is acceptable, for that particular cell. In addition to causing unnecessary wear to the already worn cell, there is some potential that the cell may "vent with flame" under these conditions. The CC/CV charging algorithm is used, not only to extend cell longevity, but as a safety measure, as well.
So, one more time, "charging voltage" and "charged cell voltage", as pertains to all chemistry of Li-Ion cells, are two different voltages, and should not be confused. The first is the voltage of the charging circuit (cell included) and the other is the voltage of the cell independent of, or removed from the charger. These two voltages will very rarely ever appear to be the same. I say "appear to be the same" because the cell voltage independent of the charging circuit, will always be less than the charging voltage. The only reason the two voltages may appear to be the same, is the limited resolution of the voltage measuring device, and this situation will likely only arise with very new cells.
Dave
It's really fairly simple. As far as I know, there is no specified voltage for which any Li-Ion cell should reside at, when fully charged and taken off the charger. The only specification is the maximum voltage of the charging circuit during the CV stage of the charge. For most LiCo and LiMn chemistry Li-Ion cells, this is 4.20 Volts +/- 1%, or 4.20 Volts +/- 0.05 Volt.
When a cell is removed from the charger, the cell voltage will decline, to some degree, depending on the age of the cell, it's use history, actual ingredients and compoents used in the cell (which varies from manufacturer to manufacturer), and so on.
I think part of the problem may be confusion between the terms "charging voltage" and "charged cell voltage". These are two different terms and are not really directly related to each other. As a result of the CC/CV charging process however, a cell will be limited to a voltage which is equal to, or less than the CV voltage of the charger. It will never be higher.
It alarms me that many strive to charge their LiCo, or LiMn cells so that, after charging, they read 4.20 Volts off the charger. Some have even gone so far as to modify chargers (usually inexpensive ones that don't use a proper charging algorithm to start with) so a voltage reading after removal from the charger of 4.20 Volts can be obtained.
This modification is potentially damaging to cells, and IMO, a dangerous practice. The older, or more used a Li-Ion cell is, the more likely it is to become unstable. The worst thing you can do to an old, or unstable cell, is to charge it to a higher voltage than is acceptable, for that particular cell. In addition to causing unnecessary wear to the already worn cell, there is some potential that the cell may "vent with flame" under these conditions. The CC/CV charging algorithm is used, not only to extend cell longevity, but as a safety measure, as well.
So, one more time, "charging voltage" and "charged cell voltage", as pertains to all chemistry of Li-Ion cells, are two different voltages, and should not be confused. The first is the voltage of the charging circuit (cell included) and the other is the voltage of the cell independent of, or removed from the charger. These two voltages will very rarely ever appear to be the same. I say "appear to be the same" because the cell voltage independent of the charging circuit, will always be less than the charging voltage. The only reason the two voltages may appear to be the same, is the limited resolution of the voltage measuring device, and this situation will likely only arise with very new cells.
Dave
