XTAR WP2 II ...not impressed.

Only charged a 18650 Panasonic to 4.174v, battery is basically brand new. Used a Fluke DMM for the reading.
Looks like I'll be returning it to the seller at my expense.

That's perfectly within specs. If +/- 1/40th v doesn't suit you, you should consider a high-end hobby charger.

LOL

4.2 is a center of range spec. A bit above or below that is ok.


The cells actually last longer if you don't try for 100%






4.174/4.2 = 0.9938

0.006 difference.


That's WELL within the range that a battery would be charged to.



What's the accuracy of your Fluke DMM?

Standard Li-Ion resting voltage after charging is 4.20v +- .05.

Johann said:

Only charged a 18650 Panasonic to 4.174v, battery is basically brand new. Used a Fluke DMM for the reading.

Click to expand...

That is just about the perfect voltage.

hellokitty[hk] said:

Standard Li-Ion resting voltage after charging is 4.20v +- .05.

Click to expand...

No, charging voltage is 4.2 +/- 0.05 volt, resting voltage will be lower. How much lower depends on a lot of factors, including age of battery, termination current and time since charging.

A charge curve looks like this (This is from one of my battery tests):

Johann said:

Only charged a 18650 Panasonic to 4.174v, battery is basically brand new. Used a Fluke DMM for the reading.
Looks like I'll be returning it to the seller at my expense.

Click to expand...

If the battery came off the charger at 4.20 V the charger would be defective. If the battery comes off the charger at 4.17 V the charger is working perfectly.

Johann said:

Only charged a 18650 Panasonic to 4.174v, battery is basically brand new. Used a Fluke DMM for the reading.
Looks like I'll be returning it to the seller at my expense.

Click to expand...

I charged Panasonic 18650A(3100mAh) by using Xtar WP6 & Xtar WP II charger and both constant charge voltage is 4.2±1% as shown in the manual specifications.
Rounding off the numbers to three decimal places, I got the final voltage 4.18~4.19V and it depends on the charging time mostly if the batteries are brand new.

I prefer using a charger that charges the cell to 4.17v
In fact, 4.1X volt is fine, remember 'less is more' for li-ions, especially unprotected cells:wave:

4.2, 4.17,4.1 wont have a large difference in their capacity

candle lamp said:

I charged Panasonic 18650A(3100mAh) by using Xtar WP6 & Xtar WP II charger and both constant charge voltage is 4.2±1% as shown in the manual specifications.
Rounding off the numbers to three decimal places, I got the final voltage 4.18~4.19V and it depends on the charging time mostly if the batteries are brand new.

Click to expand...

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.

4.2±0.05V

Click to expand...

Do the math on that. Most of us would take 4.15v over 4.21v any day of the week.

You don't seem to get the point.
4.2V +/- 0.05V means that anything from 4.15V - 4.25V would be within specs.
Like TEFJ already pointed out, the XTAR charged your cells to 99% so nothing to worry about.

fvdk said:

You don't seem to get the point.
4.2V +/- 0.05V means that anything from 4.15V - 4.25V would be within specs.
Like TEFJ already pointed out, the XTAR charged your cells to 99% so nothing to worry about.

Click to expand...

You cannot measure the charge voltage, when the charge has stopped!
Look at the curve I posted earlier in the thread. There I charge to 4.2 volt (4.196), but the second after the charge terminates the voltage is 4.18 volt and one hour later it is 4.16 volt. Depending on a lot of factors the voltage could drop more or maybe a bit less.

To make people, that believe in 4.2 volt, happy, some chargers cheats and charges to above 4.2 volt. This way it is possible to measure 4.2 volt just after charge is stopped.
One well know charger that does it is the WF-139, here is one of the worst examples I have recorded:

Johann said:

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.

Click to expand...

So you have a new version of the WP II. Mine is an old one.
There is a spec. on the cardboard box of the WP6 & old WP II in detail as shown in the following picture.





Anyway, 4.2V±1% is 4.158~4.242V and it's almost same as 4.15~4.25V(=4.2±0.05V).
I think your WP II is working quite well as a charger.

this thread is somewhat odd.

My XTAR WP2 charger works as advertised and reviewed, I have a problem with that :ironic:

I love my WP2 II . It's small, safe and feels solid, and the usb out should be a standard on all chargers to come.

Yeah, the Xtar charger is working perfectly. If all cells came off a charger at the same 4.2v voltage that is indicative of a bad charger, as it just has a 'dumb' voltage cut-off. The 4.2v max is a guideline not an exact indicator for each cell. The Xtar uses a (near to) CC/CV algorithm to measure when each battery is fully charged and tailor the charge to it. As a cell gets older or lower quality over time then the ending charge at rest will be lower. If that is not the case then the charger is not working as well as it could and perhaps should be.

Again the Xtar is a good charger and the fact it charges to 4.17 on some cells and 4.16 on others is a sign of this.

The cell manufacturer's suggestion of 4.20 +/- 0.05v will maximize capacity of the cell, and minimize cycle life. Most of us want to get 500-1000 cycles out of our cells at near-full-capacity, not 100-500 and then a steep drop in real capacity.

Johann said:

Actually, the manual specifies 4.2±0.05V...see photo below.

Click to expand...

That does not mean the battery is supposed to be charged to 4.2 V. You are not interpreting the specifications correctly. Take a careful look at the posts by HKJ where he explains this in great detail.

I'll mention once again that if you take a battery off the charger and it measures 4.20 V the charger is defective.

RedForest UK said:

Yeah, the Xtar charger is working perfectly. If all cells came off a charger at the same 4.2v voltage that is indicative of a bad charger, as it just has a 'dumb' voltage cut-off. The 4.2v max is a guideline not an exact indicator for each cell.

Click to expand...

I have done a test with different charge terminations, mostly to measure capacity, but it also shows what voltage the the battery has after termination. With some conditions you might get very close to 4.20 volt just after charge termination, but it will not last for long.
I hope to do some more test with this, when my battery test is finished in a couple of months.

AnAppleSnail said:

The cell manufacturer's suggestion of 4.20 +/- 0.05v will maximize capacity of the cell, and minimize cycle life. Most of us want to get 500-1000 cycles out of our cells at near-full-capacity, not 100-500 and then a steep drop in real capacity.

Click to expand...

The 4.2 volt charge will make the cell perform as specified in the datasheet. Lower charge voltage will probably give more charging cycle and will give longer lifetime. The lifetime part is probably more important for most flashaholics, not many need to do a full charge each day of their LiIon batteries.