Consumer Li-Ion "cradle" charger roundup...

[KiwiMark]

Charging method:
Constant Current @~250-350mA per channel (seems to vary) with V-test every ~1 second (pauses charging for a fraction of a second to take the reading) till 4.20V V-test is achieved.

Safety Information/Warnings:

• The charging method used here is not recommended by any Li-Ion cell manufacture that I am aware of. On smaller cells charging voltage can reach and even exceed 4.35V. Small protected cells will often terminate the charge via PCB.

I have 2 of these chargers (WF-139) and they seem to work well - though the charge method is different from the standard one. It occurs to me that the charge should be quicker by not tapering off the current at the end and that the final charge state should be exactly the same as achieved by the standard CC/CV method. The only real difference would be that during the final stage of charging the voltage of the cell is higher while the charging current is flowing than the 4.2V which is recommended as a maximum voltage. But given that the time a cell spends above 4.2V is short - does anyone know what sort of damage that does to a cell? I'm thinking that it would not be much degradation (especially for cells that are not charged often, but would be more of a concern for cells topped up regularly).

I consider rechargeable batteries to be a consumable item that needs to be replaced every few years anyway, but I wouldn't want to cut down the useful life of a Li-ion cell from 4-5 years down to 2-3 years - that would be quite a large hit to the lifetime. If we are talking about cutting down an average lifespan of 4.5 years down to 4.4 years then I really couldn't care less. I am doubtful that the Li-ion year lifespan would be reduced by more than 10% and suspect it would be much less than 5%, maybe only a fraction of 1% - if this is the case I will happily use the WF-139 whenever I like.

I do have a couple of Turnigy hobby chargers that I can use most of the time - but there are times I want to recharge a bunch of different cells all at the same time, having 2 WF-139 chargers & 2 hobby chargers & 2 NiMH chargers means I can charge 8 NiMH cells and a bunch of Li-ion cells all at the same time. But I do wonder about how much or how little the WF-139 charger's 'unusual' charging method affects the life of the cells it charges.

My Turnigy chargers are much better for my 32600 Li-ion cells because I can charge at 2 or 3 amps and get them full in a quick time (and they use the CC/CV method). The 'cradle' chargers are a very convenient & easy way of charging up the 16340 & 18650 cells without worrying about settings - much better option for the average Joe.

 

[mdocod]

... But given that the time a cell spends above 4.2V is short - does anyone know what sort of damage that does to a cell? I'm thinking that it would not be much degradation (especially for cells that are not charged often, but would be more of a concern for cells topped up regularly).

I suspect as you do, that it would depend on how frequently the user is topping off.

Read response #17 in this thread:
http://www.candlepowerforums.com/vb/showthread.php?t=268431

The charger he is referring to there uses a relatively fast charge rate (~800mA IIRC) and a CC only charge algorithm that is actually terminated by the PCB. Resulting termination and resting voltages at the cell will usually measure ~4.15-4.23V with this type of charger depending on the internal resistance of the cells charged. But it's important to note, that this charge method when used with the cells it is intended for (18500, 17670, and 18650 size PROTECTED), is producing almost the exact same charge routine that a WF-139 will when charging a RCR123/14500 size cell.

I don't think anyone has any way of knowing absolutely what difference in wear and tear this charge method makes. I'm inclined to say that as cells have become safer and more abuse tolerant in recent years, these CC only charge methods are reasonable provided that there is a true termination.

The biggest problem with the WF-139 is not knowing what you're going to get or what you have unless you know how to run some tests. There is a version out there that will completely skip termination if a cell that is already mostly charged is installed. The ramp-down and termination algorithm starts around 4V. If the charger doesn't see ~4V at the cell through the charging process, it will never initiate the algorithm that results in termination. The original 139, (12V open circuit), will trickle charge endlessly after the light goes green, probably shooting for 12V. (PCBs will prevent it ever achieving this, but trickle charging from 4.20V up to 4.35V would be absolutely horrendous wear and tear for most cells).

I do have a couple of Turnigy hobby chargers that I can use most of the time - but there are times I want to recharge a bunch of different cells all at the same time, having 2 WF-139 chargers & 2 hobby chargers & 2 NiMH chargers means I can charge 8 NiMH cells and a bunch of Li-ion cells all at the same time. But I do wonder about how much or how little the WF-139 charger's 'unusual' charging method affects the life of the cells it charges.

Have you considered building cradles or gutting a few cheap li-ion cradle chargers so that you could use your turnigy chargers to charge more cells at once?

You can charge li-ion cells in parallel and they will balance out just fine. The important thing is that the cells are within say ~20% or so of each-others state of charge when put in a circuit together in parallel so that no extreme charge/discharge rates occur as the cells balance with each-other. Making an effort to match up cells that are of a similar capacity and internal resistance is also semi-important but not entirely necessary. Set charging rates depending on how many cells and what capacity are installed in the cradle. Shoot for ~0.5C charge rates. Use diligence when installing multiple cells insuring that none are installed backwards 😉

Eric

 

[45/70]

Do you have any links to any real testing of this charger? I read the 4 page thread which was mostly guesses and wishes, some reported too high voltages, and the "proof" that it doesn't trickle charge isn't valid, my XXC charger will pass that test as well (it trickle charges and still the cell voltage will never be above 4.20).

I think there is a review on the YOHO somewhere here, you may have to look back a few years. As I remember, the YOHO does trickle charge, but at a very low rate, similar to the HG-103W9V, so you really should pull the cell(s) when the LED turns green. That was one of the reasons it's algorithm wasn't considered as good as the Pila's. Discussion of the YOHO is moot anyway, as it has apparently been discontinued.

The Pila's algorithm isn't perfect either. One of the shortcomings is, that it terminates charge at a set 50mA during the CV stage. This generally falls close to the acceptable range of 0.03-0.1C (where "C" is the charge rate, not the capacity of the cell) for most cells, however. At least, it does terminate the charge.

Because it's probably expensiver? "Logarithmic Current" charging is fine for most people, myself included, as long as the charge voltage doesn't rise above 4.20: it will take a bit longer but it's not harming the cell.

Most people couldn't care less about the proper algorithm if those chargers cost much more and are just slightly faster.

"Logarithmic Current" charging may be fine for most people, I guess, as long as they understand that it is not recommended by the manufacturers who make the cells, and understand the possibility of damaging the cells, as well as the safety risks involved. Also a charger that maintains a cell at a certain voltage after charge completion, is trickle charging. A proper charge algorithm such as the Pila's, or a hobby charger, terminates the charge upon completion, as can be witnessed by a drop in the cell's voltage.

It will still be in the final part of the CV phase for some hours after the LED turns green, going from 4.17 to 4.20 using a very low current, and I will have powered it off long before it reaches 4.20. That's why I said it was fine, not that an actual trickle charge is OK. And the charge voltage is 4.20 so it won't charge it higher than that.

There is too much emphasis on a charger not charging over the maximum voltage recommended. While this is certainly important, it's just as important, or in some cases more important, that a charger terminates the charge and doesn't trickle charge after the charge is complete. While a charger that maintains ~4.20 Volts after charge completion is probably less dangerous than one that keeps trickling to 4.35 Volts, in either case they are both trickle charging. This is a safety risk in addition to being bad for the cell, as pointed out in my last post. A proper CV stage, as recommended by the Li-Ion cell manufacturers, terminates the charge at 0.03C or above, thus eliminating the possibility of trickle charging.

Do you think the recent activity this has sparked will generate any results?

Eh, doubtful. :sigh:

Dave

 

[bstrickler]

Does the DSD do the 2rd "topping stage," or does it just bring the batteries to 4.2 volts and leave them there without full capacity?

My DSD stops mine at around 4.1-4.14 volts. Since most of my stuff is 500ma-1a draw, that extra 0.05-0.1 volts isn't gonna make a big difference to me.

The only thing I hate about my DSD, is that it charges at about 220 ma, not the 450 rated.

~Brian

 

[mdocod]

Do you have any links to any real testing of this charger? I read the 4 page thread which was mostly guesses and wishes, some reported too high voltages, and the "proof" that it doesn't trickle charge isn't valid, my XXC charger will pass that test as well (it trickle charges and still the cell voltage will never be above 4.20).

Your pressure to generate results has done so 🙂 I'm glad you have forced the subject because we can now put 4 pages to rest as a waste of our time.

I've just partially-completed a really thorough test of the YOHO-122. It holds 4.20V under trickle charging and lacks true CC/CV charge method just like many others. Previous testing that I conducted was not in-depth enough to un-cover the trickle behavior. It was literally tricking one of my DMMs. (the last time I tested it I was using a different DMM, I've since obtained a slightly better one) All of the positive thoughts I had about the YOHO-122 can now go out the window with the rest of this garbage. My results can be found in the first post of this thread. I have numerous personal statements made in favor of the 122 around the forum that I have just proven incorrect. I hate being wrong but I'm going to have to go around and do some damage control here. I was wrong about this charger.

What I have really proved here again, is that the Pila IBC remains the only charger that is worth a handful of beans.

From here on out, until a manufacture wants to compete with the Pila IBC and drive this price down for a competent charger, I'll be telling people to pony up $50 if they have any interest in running li-ion cells. I've said it before but didn't hold true enough to it: "li-ion chargers will be guilty until proven innocent."

A revised version of that statement will be as follows: "All Li-Ion chargers should be considered guilty until proven innocent, if the manufactures of these chargers would like me to treat them less like the IRS would and more like the US constitution would, then they are going to have to make some changes."

-----

OK, having said that, for healthy new cells, combined with a monitored charge and cell removal upon "solid green," the charger is really good in some ways. I'm going to have to keep this charger on hand for when I need to charge up a lot of cells quickly, like when a storm is headed our way and I want to be ready with plenty of reserve power for flashlights in case of a power outage. It's faster than any cradle charger I have tested.

Eric

 

[mdocod]

Exactly how fast?

I've just completed a charge speed test comparing 5 different chargers. The results are in the first post of this thread.

I had previously done a couple quick tests using IMR16340s, but figured, I better do a test with larger cells from a good low state-of-charge (~20%) to make absolutely sure.

The IBCs 600mA rate charged faster than the Cytac 2x18650 claimed 1A charging rate. And only came in a few minutes behind the speed of the YOHO-122 (also rated 1A).

Both of these "1A" chargers never really spend any time at 1A, and they both taper down their charging rate through the charge long before the target voltage is reached. The continuous 600mA CC of the IBC is able to compete because it doesn't drop off until the target voltage is reached.

Eric

 

[45/70]

Interesting results with the YOHO-122, Eric.

I didn't realize that it didn't follow the CC/CV algorithm, at all! Still, it seems to do a pretty good job in that the cells come off at an exceptable voltage, and the trickle charge simmers down to such a low amperage that if the cells are pulled off within a reasonable time after the indication of charge completion, the cells won't suffer too badly. Just the same, overall, the Pila is better with it's actual termination of charge and I agree, is the only proper cradle charger, which is the topic of this thread.

Nice work! :thumbsup:

From post #15 in this thread,

I expect to see a major western government crack-down on this market in the next few years. Big brother is looking for the next target at all times. All can be been avoided if consumers purchase with their brains rather than their shampoo.

This is my primary reason for commenting in these type threads. I'm selfish, and don't want others ignorance of the proper use and care of Li-Ion cells to ruin my hobby! I really couldn't care less whether people use a proper charger and burn their house down, or whatever! Me me me! There, I said it. :naughty:

OK, just kidding (calm down TMG, if you read this🙂), but there is a fair amount of truth in that statement. If folks (and cheapo charger manufacturers) aren't willing to better, or perhaps I should say completely understand and implement the proper care and feeding of Li-Ion cells, they will become harder to obtain. Actually, this has already started to some extent, unfortunately. :sigh:

Dave

 

[Black Rose]

Thanks for the more in-depth test of the Yoho-122.

I always monitor the charge process and pull the cells as soon as the light turns green, but still it's frustrating to have to continue the quest.

Later this month I think I'm going to spend the money and get myself an Accucel-6 hobby charger (cheaper than importing an IBC @ $75 with shipping) and be done with it.

EDIT: Priced out, the Accucel-6, power adapter, and shipping are only $20 cheaper than an IBC.
Then there are the cradles and/or balance leads to figure out

 

[45/70]

Good solution, Black. They are a bit more complicated to get going with the necessary cradles, hookups etc, but hobby chargers seem to work quite well. The only caveat I see with them, and it's a very minor one, is that most hobby chargers terminate the charge at 0.1C (of the charge rate) rather than 0.03C, so the cells may not come off as fully charged as with say, a Pila. The actual difference in capacity is of course minimal, and the cells will last a bit longer. 🙂

Dave

 

[mfm]

"Logarithmic Current" charging may be fine for most people, I guess, as long as they understand that it is not recommended by the manufacturers who make the cells, and understand the possibility of damaging the cells, as well as the safety risks involved.

What is the safety risk with logarithmic charging?

Good solution, Black. They are a bit more complicated to get going with the necessary cradles, hookups etc, but hobby chargers seem to work quite well.

I don't think hobby chargers are better for most people, quite the opposite:

The bad incidents with the cheap Li-ion chargers discussed here are limited to the primary transformer side going poof, sometimes with some smoke and some theoretical problems with [FONT=Verdana, Arial, Helvetica, sans-serif]corrosion and plating of metallic lithium that noone has reported beeing a victim of.

That is in sharp contrast to people with hobby chargers who have burned down houses, cars, trucks, trailers, you name it. The fiddling with complex settings and various selfmade cradles is a much greating risk than the theoretical trickle charge that usually won't happen anyway.

This is from using a hobby charger:

BTW, got my new HG-1210W charger today, we'll see if it's any good...
[/FONT]

 

[45/70]

What is the safety risk with logarithmic charging?

As I pointed out already, a CV charge that doesn't terminate, trickle charges. I think the approach to charging Li-Ion cells should be one that follows the manufacturers recommendations, which are very strict. It's better to be safe than sorry when dealing with cells that have so much potential energy, and again, they do not recommend a logarithmic charging method, only CC/CV with charge termination.

On hobby chargers being more dangerous than cradle chargers, I don't think you have the statistics to back that assumption up. There are probably a hundred (or more) times as many people using hobby chargers for R/C use than people charging individual Li-Ion cells for flashlights, or any other use. It's a bit like saying Honda Accords are more dangerous than 1939 Studebaker pickup trucks, because they are involved in more accidents. Any method of charging Li-Ion battery cells can be dangerous. It's the nature of the beast.

BTW, got my new HG-1210W charger today, we'll see if it's any good...

Do let us know what you think.

Dave

 

[KiwiMark]

Have you considered building cradles or gutting a few cheap li-ion cradle chargers so that you could use your turnigy chargers to charge more cells at once?

You can charge li-ion cells in parallel and they will balance out just fine. The important thing is that the cells are within say ~20% or so of each-others state of charge when put in a circuit together in parallel so that no extreme charge/discharge rates occur as the cells balance with each-other. Making an effort to match up cells that are of a similar capacity and internal resistance is also semi-important but not entirely necessary. Set charging rates depending on how many cells and what capacity are installed in the cradle. Shoot for ~0.5C charge rates. Use diligence when installing multiple cells insuring that none are installed backwards 😉

Eric

I can easily charge up to 8 cells at once - I have a Elephant II body running 8 x IMR 18650 cells. For that the hobby charger is the best one to use. (Lux Luthor made me up some balancing leads with magnets)

But I have several single cell lights - when I decide to go through my lights and charge the cells from them I need fully independent charging channels. If I grab the 14500 from the light in my front left pants pocket and the 16340 from the light in my left jacket pocket and the 18650 from the Jet-IIIM - well you get the idea. (I have lights that use 1 x 10440, 1 x 14500, 1 x 16340, 1 x 18650, 2 x LiFePO4 16340 - with several lights using some of those configs) Of course I don't use the WF-139 for the 10440 cells, but the others charge fine on the WF-139 or the hobby chargers.

 

[mdocod]

The Million Dollar Question:

Anyone tested one of the cheap popular hobby chargers to ensure that they are terminating correctly?

 

[Mr Happy]

As I pointed out already, a CV charge that doesn't terminate, trickle charges. I think the approach to charging Li-Ion cells should be one that follows the manufacturers recommendations, which are very strict. It's better to be safe than sorry when dealing with cells that have so much potential energy, and again, they do not recommend a logarithmic charging method, only CC/CV with charge termination.

I don't believe there is anything required about the CC/CV charging algorithm. It just happens to give an optimum charging speed.

The key things about Li-ion charging are:

1. Do not exceed the maximum charging current (that's what the CC bit does -- it applies the maximum charging current, but you could use lower currents if you like);
2. Do not exceed the maximum charging voltage (that's what the CV bit does -- it applies the maximum charging voltage, but you could use lower voltages if you like);
3. Stop charging (terminate) when the cell is charged. All chargers should do this.

What you will find is that if you use lower charging currents or voltages (such as with the logarithmic charging behaviors), then charging will take longer. However, as long as the charger terminates at an appropriate time this is just an inconvenience, not a safety hazard.

The laws of chemistry and physics are complicated, and the universe does not generally come up with neat and tidy solutions such as a "perfect" charging algorithm. Everything involves pluses and minuses, and compromises between opposing factors.

 

[Black Rose]

The Million Dollar Question:

Anyone tested one of the cheap popular hobby chargers to ensure that they are terminating correctly?

Excellent question.

And with the Accucel-6 (I'm assuming that's the one you are referring to) there are 2 versions now. The old 5A version and the recently updated 6A version.

 

[45/70]

I don't believe there is anything required about the CC/CV charging algorithm. It just happens to give an optimum charging speed.

Thanks for the input Mr H.

So, a pure logarithmic charging algorithm may work, although not recommended by any manufacturer that I am aware of.

However, as long as the charger terminates at an appropriate time this is just an inconvenience, not a safety hazard.

And, a logarithmic charging algorithm that does not terminate the charge is a safety hazard. That was my point. 🙂

Dave

 

[mdocod]

Hi Mr Happy,

I entirely agree with your 3 considerations there. Amazing that they can't build a charger that will cover all 3 bases, and I agree, there is a LOT OF ROOM for variations within those parameters set. If these 2 Cytac chargers, charged in the exact same way that they charge right now, but actually terminated when the light went green, then I would be calling them the only reasonable alternative to the IBC. My samples charge a hair higher than I personally like but not by enough to be a concern.

---------------

I want to give credit where credit is due here:

CPF member lebox97 (illuminationgear.com) sent me the Cytac chargers for testing, and is sending me a few more chargers for testing in the next few days here. I figure I'll probably have them in a week or so. He is trying to find an alternative to the IBC (which he offers) to offer on his site that he can feel comfortable selling. I'm more than happy to test any chargers being sent to me as it benefits all of us. He has latest gen 139s which are semi-reasonable IMO, but I think we'd all like to see something better.

Eric

 

[LEDAdd1ct]

1) Eric, thank you for all the hard work you've put into this thread.

2) I would like to get a second charger, but a second IBC is out for now. I've also toyed with the prospect of getting a friend into 18650 cells, but I wouldn't want to get him an unsafe charger, which, according to the latest facts in this thread, is pretty much every charger *but* the IBC.

The one remaining charger on my "safe or not safe?" list is the Shekor. Do you have one of these to play with yet?

 

[hazna]

I'm a little confused about the Pila IBC. According to their own specifications they claim to have a standmode mode where it trickle charges???

http://www.pila-usa.com/pilaparts/charger.html

 

[hazna]

I'm a little confused about the Pila IBC. According to their own specifications they claim to have a standmode mode where it trickle charges???

http://www.pila-usa.com/pilaparts/charger.html

Nevermind, its explained here (point 5):
http://www.candlepowerforums.com/vb/showpost.php?p=2534238&postcount=1