New XTAR WP2 II Li-ion charger

Features:
XTAR WP2 charger is apply to charging for two 14500/ 14650/ 17670/ 18500/ 18650/ 18700 3.7V Li-ion battery simultaneously but independently, it can charge for 10440/16340 when use 2pcs spacers. It is designed with undervoltage lockout and algorithm (TC.CC.CV) charging method which can monitor the battery's status real time and control charging safe automatically.
WP2 designed with USB output function, use fully charged battery can supply electricity to those devices power below 5.0V/500mA.
WP2 Charger adopts reverse-polarity protection circuit board and over/under voltage disconnecting technology, can prevent the possibility like sundries, wrong polarity and misoperation caused short circuit.
WP2 built battery over discharging activating function, it can repair varying degrees discharged battery and then charging automatically, it is your first choice safer and reliable Li-ion battery charger.

more info qualitychinagoods

I received today from qualitychinagoods good build quality, I think this is one of the best "low-budget" li-ion charger

switch
0 - USB 5.0V/500mA
1 - 500mA
2 - 1000mA

pics, details

Nice pictures :

Charges @ 1A and 500mAh - 3 position switch at the front ...
0 position is for the USB charge function
1 Position is for 500mAh charge rate
2 position is for the 1A charge position

So far seems to perform solidly , still testing .. But looks good ..

Did I mention those are some nice pictures ? What is the termination voltage range on that one ? If one may ask ...

Cool I'll be interested to see if the circuit has the same problem as with the V1 that causes the voltage and current to constantly spike up and down. I observed the same behavior in other Li-ion charge IC's when they are overheating.

fully charged Jetbeam 18650

jasonck08 said:

Cool I'll be interested to see if the circuit has the same problem as with the V1 that causes the voltage and current to constantly spike up and down. I observed the same behavior in other Li-ion charge IC's when they are overheating.

Click to expand...

I have not seen that problem on WP2, but it does turn off the charge current each second to check cell voltage.

HKJ said:

I have not seen that problem on WP2, but it does turn off the charge current each second to check cell voltage.

Click to expand...

How do you know its turning off the charge current every second to check voltage? That's definitely not proper behavior of any Li-ion charging IC I've ever heard of... I'm more inclined to think that the IC is in thermal limiting mode and overheating, thus reducing the current to pulses to avoid frying the IC. When i measured the current a while back I constantly saw spikes form 100mA to 500mA.

jasonck08 said:

How do you know its turning off the charge current every second to check voltage? That's definitely not proper behavior of any Li-ion charging IC I've ever heard of... I'm more inclined to think that the IC is in thermal limiting mode and overheating, thus reducing the current to pulses to avoid frying the IC. When i measured the current a while back I constantly saw spikes form 100mA to 500mA.

Click to expand...

My Ultrafire WF-188 does this same pulse mode charging. I'm using the 300ma charge rate.

EDIT: Posted in the wrong thread, but nice pics, gopati!

Dave

jasonck08 said:

How do you know its turning off the charge current every second to check voltage? That's definitely not proper behavior of any Li-ion charging IC I've ever heard of... I'm more inclined to think that the IC is in thermal limiting mode and overheating, thus reducing the current to pulses to avoid frying the IC. When i measured the current a while back I constantly saw spikes form 100mA to 500mA.

Click to expand...

With a oscilloscope connected to the charger it is easy to see. This "turning off to measure voltage" is very common behaviour on LiIon chargers, it has nothing to do with overheating.

Be-Seen Triker said:

My Ultrafire WF-188 does this same pulse mode charging. I'm using the 300ma charge rate.

Click to expand...

HKJ said:

With a oscilloscope connected to the charger it is easy to see. This "turning off to measure voltage" is very common behaviour on LiIon chargers, it has nothing to do with overheating.

Click to expand...

Ultrafire is a very low quality charger with only a constant current charge method. This charger claims to have a CC/CV charge profile, and as far as I am aware, this is only achievable by the use of a Li-ion charging IC. No Li-ion charging IC i've seen should exhibit this type of behavior of measuring the voltage every 1 second, and decreasing the voltage and current as a result.

HKJ, have you logged the average charge current of the charger? I've only done 5 minutes worth of testing with the WP2, and I observed pulses of 100mA to 500mA constantly. Your charging graphs look somewhat similar to my initial testing of the LTC-4054-4.2 when the IC was overheating. It would do about the same thing, pulse for about 1 second then stop then pulse again. This only happened however during the CC stage, because there is far less heat dissipated through the IC during the CV stage.







The pulsing and noise is quite similar. Can anyone point out what type of main chips they are using on the PCB?

jasonck08 said:

Ultrafire is a very low quality charger with only a constant current charge method. This charger claims to have a CC/CV charge profile, and as far as I am aware, this is only achievable by the use of a Li-ion charging IC. No Li-ion charging IC i've seen should exhibit this type of behavior of measuring the voltage every 1 second, and decreasing the voltage and current as a result.

Click to expand...

You can easily make a LiIon charger with a small microprocessor controlling a smps. I believe that I have seen this packed into a single IC.

jasonck08 said:

HKJ, have you logged the average charge current of the charger? I've only done 5 minutes worth of testing with the WP2, and I observed pulses of 100mA to 500mA constantly. Your charging graphs look somewhat similar to my initial testing of the LTC-4054-4.2 when the IC was overheating. It would do about the same thing, pulse for about 1 second then stop then pulse again. This only happened however during the CC stage, because there is far less heat dissipated through the IC during the CV stage.

The pulsing and noise is quite similar. Can anyone point out what type of main chips they are using on the PCB?

Click to expand...

I have not been running a average (not anymore than my meters are doing), but I have used an oscilloscope to see the current pulses, they do not look like any overheating shutdown.
The chip used is not a LTC-4054 or any of the derivates, that chip uses linear regulation and this charger does not use linear regulation (The 62 Khz frequency in the current shows this).

Measuring the voltage during OFF pulse would measure something that's closer to OCV, which isn't what you're aiming for when you're charging Li-Ion...

shadowjk said:

Measuring the voltage during OFF pulse would measure something that's closer to OCV, which isn't what you're aiming for when you're charging Li-Ion...

Click to expand...

You are not measuring the rest voltage, but the actual voltage at the chemistry, eliminating all resistance. As you can see on my graph the voltage will drop a bit, when charging is stopped.
But as you also can see from the graph the charger never goes above 4.2 volt, even when charging.

The CC/CV algorithm uses the voltage during charge, not voltage at 0 current, so I don't know what use there'd be to cycle current on/off, except that if you measure both voltages you can work out the internal resistance of the cell + circuit/lead resistances...

I agree the measuring of the cell voltage every second is not really what the CC/CV algorithm calls for. This pulsing / noise whether intentional or not is a design flaw in the unit IMO.

It's really OK to use some different algorithm than CC/CV. CC/CV not a prescribed rule that you must follow lest terrible things happen to you.

As HKJ explains above, there are prescribed limits on the charging of the cell that must be satisfied: you should not exceed the maximum voltage (4.2 V) and you should not exceed the maximum charging current (e.g. 0.8C). Within those limits there are a whole variety of charging algorithms that could be used, and for various reasons some of them could be a better engineering choice than others. They are not wrong, merely different.

It happens that a pure CC/CV algorithm will charge a cell to completion in the shortest time compared to any other algorithm. If that is your goal, then a pure implementation of CC/CV is good. However, if you perhaps want an efficient charger, a small charger, a light charger, or an economical charger, then charging as fast as possible may not be the goal that drives your design decisions. Good engineering as about making the right decisions for the right reasons. Blindly following rules because they are engraved on a stone tablet is never a good basis for design.

HKJ has tested this charger and analyzed it carefully. The analysis shows it is charging safely and respecting the prescribed limits of the cells. Therefore the design is perfectly satisfactory and it is not defective at all.

@ Mr happy, true that the charger may not be damaging to cells, and probably works just fine, however the two things I have a problem with are:

1) Claims to be a CC/CV, but it's not really.

2) Claims 500mA / 1000mA charge current, but with constant pulses from ~100mA to 500 or 1000mA, its clearly not charging at those currents.

jasonck08 said:

@ Mr happy, true that the charger may not be damaging to cells, and probably works just fine, however the two things I have a problem with are:

1) Claims to be a CC/CV, but it's not really.

2) Claims 500mA / 1000mA charge current, but with constant pulses from ~100mA to 500 or 1000mA, its clearly not charging at those currents.

Click to expand...

From an examination of the review measurements provided by more than one reviewer here, those claims seem close enough to me. I would be very happy to own and use the charger. (I come at this with a technical background and therefore some appreciation of the design choices faced by the designers of the charger. I think the demand for pure CC/CV behavior with perfectly smooth lines on the graphs would result in a different charger from the one you see--a charger that would likely be bigger, heavier, more expensive, hotter in operation and unlikely really to offer much practical benefit for those differences. I want the charger reviewed here, not the ideal CC/CV charger of theory.)

jasonck08 said:

@ Mr happy, true that the charger may not be damaging to cells, and probably works just fine, however the two things I have a problem with are:

1) Claims to be a CC/CV, but it's not really.

Click to expand...

As you can on the curves in my review it is close to a CC/CV charger.

jasonck08 said:

2) Claims 500mA / 1000mA charge current, but with constant pulses from ~100mA to 500 or 1000mA, its clearly not charging at those currents.

Click to expand...

My measurements does not show that, it shows 500 mA / 1000 mA with short breaks to measure the voltage. Please provide some oscilloscope traces showing the swing between 100mA and 500 mA current. A typical DMM is not fast enough to show the off pulses and will show some random value between the charge current and some lower value (could be 100mA, but it depends on the DMM).