Review of Charger Xtar XP4

[ggroyal1117]

I use Dr. Marty's conductive grease to lubricate the slides.

http://www.bigsquidrc.com/dr-martys-easy-on-conductive-grease-review/

 

[RI Chevy]

Also some diaelectric grease or Super Lube!

 

[rlapporte]

I realize that this thread is a bit old, but I was trying to research the right current to use for charging my lithiums in my new XTAR VP2 and this thread touches on it. I assume I should be using 0.25A for 18350 and RCR123. The owner's manual states that you should use 0.25A up to 18700 but it takes forever to charge my 18650 at 0.25A.

Several concerns...

I'm most concerned with safety. Is there any risk to charging at 0.25A? As I understand it, it can be risky to undercharge a cell because the charger doesn't recognize when it's fully charged.

My next concern is long term battery life. If I charge at 0.50A or 1A, am I shortening the life expectancy?

Of course, I'd love to charge the batteries faster, but not if safety or battery life would be compromised.

And on the topic of charging faster, I'd love a 4-cell charger that is just as good. In reading the reviews, I'm not sure that anything else out there compares to the XTAR. Will the XP4 be the next best thing if I wanted to charge 4 simultaneously?

Thanks

 

[HKJ]

I realize that this thread is a bit old, but I was trying to research the right current to use for charging my lithiums in my new XTAR VP2 and this thread touches on it. I assume I should be using 0.25A for 18350 and RCR123. The owner's manual states that you should use 0.25A up to 18700 but it takes forever to charge my 18650 at 0.25A.

Check the VP2 review, it has a table with my recommendations for current settings for different battery sizes.

I'm most concerned with safety. Is there any risk to charging at 0.25A? As I understand it, it can be risky to undercharge a cell because the charger doesn't recognize when it's fully charged.

That is for NiMH, with LiIon the only risk is that you fill the cell a bit more and get shorter battery lifetime due to that.

My next concern is long term battery life. If I charge at 0.50A or 1A, am I shortening the life expectancy?

As long as you stay below the batteries rated charge current, it will last the rated 300 or 500 cycles.

Of course, I'd love to charge the batteries faster, but not if safety or battery life would be compromised.

Batteries usual has two charge rating. A low one (Usual between 1A and 2A for 18650) that means it will last the rated number of cycles and the highest safe charge rate, but with reduced lifetime.

And on the topic of charging faster, I'd love a 4-cell charger that is just as good. In reading the reviews, I'm not sure that anything else out there compares to the XTAR. Will the XP4 be the next best thing if I wanted to charge 4 simultaneously?

There is a couple of LiIon chargers that can works fine with 4 channels, XP4 is one of them.

 

[ven]

I use 0.25 and 0.5A settings for my 16340 cells ,i would not use the 1A as imo a bit too much,however if you require a quicker charge 0.5A should be fine(has been for me).

I use the 0.25A setting for my 10440 cells mainly.

 

[rlapporte]

Thanks to both of you for your quick replies. So it looks like I can safely go up to an amp, even up to 1.7 amps if the charger allows for it. Very different from the chart in the Xtar manual. So HKJ, do you have a favorite 4-bay unit? I don't really care if it also does NiMH, as I already have a Maha. I'm looking for a way to quickly (and safely) charge my 18650s, 18350s, and CR123s. Considering the Xtar XP4 and the Jetbeam i4 pro, but I'm open to others. Thanks for all of your help on this.
Best,
Rob

 

[HKJ]

Thanks to both of you for your quick replies. So it looks like I can safely go up to an amp, even up to 1.7 amps if the charger allows for it. Very different from the chart in the Xtar manual. So HKJ, do you have a favorite 4-bay unit? I don't really care if it also does NiMH, as I already have a Maha. I'm looking for a way to quickly (and safely) charge my 18650s, 18350s, and CR123s. Considering the Xtar XP4 and the Jetbeam i4 pro, but I'm open to others. Thanks for all of your help on this.

Take it easy, 1.7A may be to high, depending on the battery.

Generally I like Xtar very much for LiIon chargers, they may not always be perfect, but they are never bad.
Soshine has a 4 bay unit, but due to temperature it might be best to limit it to 3 cell.
ThruNite (And Fenix) does also have a decent 4 bay unit.

There is also a Opus 4 bay analyzing charger (BT-C3100), it is not perfect and definitely not a perfect charger, but the total package is acceptable, due to the analyzing function.

I have done a review of all of them, where you can see more details.

 

[rlapporte]

thanks. I read your reviews, and they are amazing...but I'm still left wondering which one I should get I'll reread them and figure it out. I see you didn't mention the i4. Is it not in the same league as the others you mentioned?

The reason I mentioned 1.7 amps is because I read that 0.5c is acceptable and I have some 3400's.

Best,

Rob

 

[HKJ]

I see you didn't mention the i4. Is it not in the same league as the others you mentioned?

Generally I do prefer non pulsing LiIon charger.
I am working on the 2014 version off the i4, look for the review in a few weeks.

The reason I mentioned 1.7 amps is because I read that 0.5c is acceptable and I have some 3400's.

0.5C is not acceptable for all cells, for Panasonic 3400mAh it is acceptable, but not for 2900 and 3100mAh cells.

 

[rlapporte]

I see. So there's obviously not a general rule that will allow you to calculate the ideal charge current based on the capacity. Bummer.
Looking forward to your review

 

[HKJ]

So there's obviously not a general rule that will allow you to calculate the ideal charge current based on the capacity.

No. Once it was 1C and that is still a good guess for smaller cells. For 18650 the safe value is 1A.
Reading some data sheets may increase the charge current significantly for many cells, some high current cells can be charged at 2C (Price is reduced lifetime).

 

[rlapporte]

No. Once it was 1C and that is still a good guess for smaller cells. For 18650 the safe value is 1A.
Reading some data sheets may increase the charge current significantly for many cells, some high current cells can be charged at 2C (Price is reduced lifetime).

Thanks so much.

 

[Sethaas]

I will have the latest XP4 version hopefully within a week. I can post a review of the charger. It will not be as half as technical and profound as HKJ's one, but it will answer some interesting questions. Are you guys interested?

Hi Viperxp

This thread has probably been abandoned for good, but I'm interested to know if your unit has the problems that HKJ pointed out? Thanks!

 

[espresso]

I received the charger today and noticed Sanyo XX was getting too warm at 1A. It had 57°C (134F) when I decided to terminate the charge. I'll see how NiMH batteries do in the following days.

Efest IMRs worked fine with 4,16V just after the charge finished, followed by a drop to 4,15V moments later. They had around 40°C at 4x1A which is 2-3 degrees hotter then Intellicharger i4 at 4x375mA. That looks ok.

 

[HKJ]

I received the charger today and noticed Sanyo XX was getting too warm at 1A. It had 57°C (134F) when I decided to terminate the charge. I'll see how NiMH batteries do in the following days.

You will often get a fairly hot battery just before the charger terminates, due to the way -dv/dt works.

 

[kreisl]

You will often get a fairly hot battery just before the charger terminates, due to the way -dv/dt works.

with some chargers the cell gets hot around the top part because of plain heat conduction lambda from the hot positive terminal to the cold battery

 

[espresso]

Ok, it has just finished charging four Eneloops at 1A and the temperatures at the end of the charge were 71C (160F) in the upper half of each of the first three cells, vs 64C (147F) in their lower halves. An exception was the cell furthest to the right which had 64C in the upper half (didn't get the lower half of it).

So this charger will destroy your NiMH cells, in short. I'm certainly never going to use it again on 1A with NiMH cells. I will try lower modes with AAA and AA, however.

The problem is that the positive terminals, as kreisl mentioned, transfer insane amount of heat to the batteries. The terminals are still very hot minutes after removing the cells...
I'm just not sure how this heat transfer doesn't affect Li-ions... It could be that the electronics don't get as hot when the charger outputs higher voltages needed for li-ion (due to reduced power dissipation of some sort), or the larger 18650s simply absorb the heat better with their volume.

Intellicharger i4 still remains the safer charger out of the two. But I just can't tolerate slow charging speed so I can put XP4 to better use.

 

[HKJ]

The problem is that the positive terminals, as kreisl mentioned, transfer insane amount of heat to the batteries. The terminals are still very hot minutes after removing the cells...

The charger often heat the cells, but the 71C temperature you get would probably be from the -dv/dt termination.
But the XP4 do get fairly warm when charging.

Intellicharger i4 still remains the safer charger out of the two. But I just can't tolerate slow charging speed so I can put XP4 to better use.

Because i4 is charging at a low current the temperature raise will be lower and it does also use voltage termination with eneloop.


The best way to keep the batteries cool at the end of the charger is to termination before the batteries are full as a lot of chargers do. I.e. if you want cool batteries go after a charger with voltage termination, if you want full batteries go after a charger with -dv/dt termination.
A charger with a fan can keep the temperature lower, but a -dv/dt termination will still get warm.

 

[espresso]

While I do agree that dv will cause higher temperatures than peak voltage termination, I cannot accept that 0,5C charging rate with properly implemented dv can cause temperature as high as 70ºC.

For instance, GP "Smart 2" charger that applies 2A to the cells, plus transfers a great deal of it's own heat to them, leaves the same cells at 60ºC at the end of charge. And this is a complete charge (maybe 50mAh less than the full capacity which is acceptable for 1 hour charger).

But XP4 takes it to a new level, it toasts cells 10ºC hotter at half the rate

 

[espresso]

Here are my final observations about this charger.

Charger terminals at 1Amp are very hot to the touch (no matter what battery you're charging). You'll burn your finger if you keep it on the terminal for longer than a second. This is definitely the reason why it heats up batteries so badly.

The only thing stopping 18650 from getting toasted is 18650's big volume. It's a massive cell which spreads heat across itself very good so contact area between charger's positive terminal and battery pole just isn't enough to transfer more heat.
But that cannot be said for smaller AA batteries. They're unable to get rid of the heat transferred by the charger, plus they warm up more than Li ions during charging.
I suppose, if you tried charging smaller li ions at the highest current setting, things would not look so good.

Why is it so hard to make a charger that doesn't heat up the batteries. They could have used wires to connect the terminals to the pcb instead of directly soldering terminals onto pcb. That's what's killing this otherwise great charger.


One more observation is that when a li ion cell is charged alone, it will receive a slightly more complete charge (4,19 vs 4,17 in the charger). If more than one cell is being charged, the charger is not able to maintain 4,19V constant voltage, and terminates at 4,17.

Charging four AA Eneloops at 500mA produced safe temperatures - around 40C at the end of the charge. But this charging rate is useless because I also experienced early termination. Eneloops charged this way yielded 1170, 1350, 1450, 1420 mAh (tested by c9000). I must say that my BC700 completely charges Eneloops at 500mA without a problem.

As for 4xAAA (eneReady) at 500mA, the hottest one had 57C at the end. If I charge only one AAA, the temperature is 37-40C.

I really hoped this charger could be the one.
But instead of making a charger that helps take away heat from the cells, they made one that feeds the heat. I have no choice but to continue piling up chargers in search for the ideal one.