Best budget charger for 14500?

(LOL im meant to be writing assignments, but ranting is more fun.. heres some stuff that I feel like putting out there)

RE: Lithium in consumer devices ... Also rememeber the amount of cell monitoring hardware used in device that use Lithium chemistry. High discharge devices (laptops) have so much going on to monitor the battery. Capacity based discharge monitoring (historical records of charge/discharge cycles, capacity etc.. stored for each and every battery used), individual cell voltage monitoring, temperature readings (im getting 4 temp readings on my battery atm), current draw, its all measured and recorded. This is all monitored by the computer, and within the battery itself, there is circuitry which interfaces with the computer. (so a battery identified as dead, will still be identified as "dead" when put into a different computer, for safety)

Our torches lack this level of monitoring, and given the highly variable uncontrolled environments (eg. people driving XM-Ls hard with RCR123 single cells (not LMR cells)), are more likely to become a problem, and are also not likely to be detected my most users until something catastrophic occurs.

Individual cell protection circuits, and a current measuring charger that provides some feedback make me a little more comfortable with running a triple 18650 torch, but all the same, its a risk that I feel is low enough with some awareness of the risk factors and how to manage them. What really scares me are the RC lithium batteries I use. Large fist fulls of lithium battery packs, discharged at 20C, and thrown about. Accordingly, they only last 50-100 cycles before their internal resistance reduces comfortable discharge rates below 5-10C (no longer useful for RC).

As a side note, the internal resistance of the RC packs are measured under 10mOhms per 2A capacity cell. I consider them end of life by the time their resistance reach 100mOhms. The lithium cells (trustfire) 18650 measures an internal resistance of around half an ohm, or 500mOhm when new. Its related to a different chemistry, but in an effort to bring this post back on topic... This internal resistance makes discharging a difficult and inefficient process, and at the same time, makes charging very slow (for a true CC/CV profile) because the cell reaches the CV stage very pre-maturely (i.e. slow charge current much earlier, takes longer to reach full charge). Maybe the other reason a True CC/CV charger doesn't exist is because such a charger that doesn't over-charge above 4.20v takes another 20% longer to charge?

Speaking of charging rate, I charge my lithiums based on their actual capacity, not what they are quoted to be. I tend to charge 0.6-1.0C, So the 18650s charge at 1.4-2.0A, the 16340s at 0.4-0.5A, the 14500s at 0.5-0.7A

I’ve been using this charger ever since i first got in THE flashlight world!
I totally recommend it. Never failed me once and it charges all my batteries to exactly 4.2V when tested with a multimeter.
I usually charge my batteries at night so even after being in THE charger after à long periode on green light they are still at 4.2V… What more can you ask from à charger this cheap! Absolutely love it.

I know the Pila is easier to use, but before I spent that kind of money, I'd just go with a hobby charger for around the same price. Then you're ready to charge anything at any rate you want.

A hobby charger is more dangerous than any cheap DX charger.

Only if you don't use it right. You can use a DX charger correctly and it can still blow up on you.

If you by "blow up" mean a capacitor popping with a little smoke then yes, otherwise very unlikely unless the cell is damaged. Also "use it right" doesn't compute with "beginner" and "you have to fiddle with your own home-made charging cradles."

That really couldn't be further from the truth. Sure you could klutz your way into some problems, but I imagine everyone here is sensible enough to ask if they are trying to do something they're not sure about.

Hobby chargers are safer for a selection of reasons, most notibly they generally have a digital read out of both voltage and charged current, they completely shut off charge to the batteries once it's reached the appropriate cut off for that batteries chemestry and you can charge batteries at an appropriate rate (mine will do 100mA to 5A).

I bought a charger from DX that would have been too unsafe to use, in that any atempt to remove it from the power socket would have resulted in you pulling the case apart exposing mains voltage wires. I bought it for parts knowing they were terribly built.

A lot of the cheaper ones vary a lot.

I bought a WF-139 ages ago and it has never given me any trouble. It has a no load voltage measured with the highest impedance meter (With my crappiest meter it measures nothing at all as it needs a new battery) I've got as a few millivolts and is supposed to be one of the early ones that overcharges cells. All I can say is that the highest voltage I've ever seen out of a cell charged in it (Overnight - more than once I've gone to bed forgetting there were cells in it) is 4.22V. Some are alleged to have shown 12V on no load. This is not good.

Others have seen over 4.3V out of cells from the same chargers. This is not good as cell life at 4.3V is maybe a few tens of cycles (Or the potential of flames the next time you charge that cell). Above around 4.5V that cell is going to die - if you are lucky it will do so gracefully. Most do but some don't.

I've had an Xtar MP1 for a few weeks now, it really is a rather nice unit and can be bought for only a few dollars on eBay. It's fixed 500mA charge rate would make it suitable for any li-ion 16340 and up. You would of course need to sort out spacers.

I have a set of these http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=170487358129&ssPageName=ADME:B:EOIBSA:GB:1123#ht_570wt_920 which I've just tried with the MP1.

One spacer is enough for a 14500 and two for a 16340, they work but I would probably recomend slightly longer spacers just to give a bit more secure fit.

The "complete shut off" is largely irrelevant as long as the charger is using the correct charge current (usually 4.20V) since then the battery will stop taking up energy at 4.20 regardess. Your cheap DX charger will do the same thing every time, so just test it a few times so you know what it does, you also can't really do anything dangerous with it, it will simply charge the inserted battery.

When you're using a hobby charger the danger is that you may have changed battery type between charges but not the settings, or your home-made mess may not be 100% working (this is why charging loose 18650s is less secure than lipo packs with balacing circuitry and contacts).

If you mess up with a hobby charger your house becomes a smoking pile of ashes.

In any case, I'd get the XTAR WP2 if I had to buy a new charger.

You can say the same about toasters, matches, etc. Used properly a hobby charger is perfectly safe. If you bang the hobby charger against your head repeatedly, however, you could hurt yourself, and in that sense is unsafe.

With respect mfm, I cannot agree with you.

"Unlike nickel-based batteries, it is not recommended to continue to trickle charge Li-Ion batteries. Continuing to trickle charge can cause plating of metallic lithium, a condition that makes the battery unstable. The result can be sudden, automatic, and rapid disassembly."

From "Charging Lithium-Ion Batteries: Not All Charging Systems Are Created Equal"

Obviously balacing circuits are of no use on single cells so that's rather irrelevant, my home modified charge solution for 18650's has less possible points of error than a lipo pack. The only probably point of failure would be knocking the cell out of it's holder, which would result in a loudly beeping and shut of charger.

There are very few ways to make a cell explode with a passible hobby charger, if you select the chemistry the cell would usually be rejected it's possible you could mix up a Lifepo4 and chartge it up to 4.2v but while that will shorten the life of the cell nothing else will happen. So you could perhapse decide to charge that 250mah cell at 20C, your charger should reject it as a bad cell once it realises that it's refusing to take the charge...there is a chance that might not happen, but then you shouldn't have done something that stupid in the first place.

You could say that the most dangerous type of charger is a dumb NiMH charger that will happily carry on trying to charge what ever you connect to it untill you turn it off, I don't think any of us are that stupid or lackadaisical.

...but yes, the XTAR WP2 looks to be a better quality version of the other economic chargers and so should be a good buy.

Well I think I'll go with the Xtar mp1 and a spacer set when I get to that point. After reading all the reviews and comments here, it seems to be the safest and best built out of the low cost chargers. Charge rate seems ideal for 14500, it terminates well and does so at a low current.

Irrelevant comparison, a toaster has to pass safety regulations and have no requirement for user interaction beyond inserting a bread slice and setting the heat level. A hobby charger can leave you with a metal- and chemical fire if you press the wrong button, have the wrong settings or your homemade charging cradles have some problem.

I know about trickle charge of Li-Ion but the thing is that it won't apply in this case if the charging voltage is low enough.

Let's say you have a cheap charger that that has a maximum charging voltage of 4.20V. During the CV phase the green light will shine when the current is below a certain limit, and after that it will continune to charge at some level. But some hours later the voltage of the cell will also be 4.20V and it can no longer accept any charge until self discharge has lowered the cell voltage.

Yep it's not great to leave it like this for weeks ofcourse, but it's an academic point compared to the hazards of a hobby charger.

I really doubt the "bad cell" detection will trigger until it's too late. People have burned down houses, cars, trailers, mobile homes etc using hobby chargers by just choosing the wrong setting (such as the charging current or cell configuration).

Oviously they are only guessing what the problem was, if it's burned down the area it was in then it's really rather unlikely the charger is still in a working state to show that it was configured wrongly.

Do you have any evidence to support that claim? If you do I would be interested to read it.

When the charger does not terminate it continues to apply power to the cell. When the cell can store no more energy the power from the charger causes lithium plating of the anode. This is very undesirable as it lowers the effective capacity and makes the cell more likely to fail with nasty consequences. To put it bluntly, there is no such thing as a low enough voltage to safely trickle charge a LiCo cell.

From the Battery University (emphasis mine): "Li-ion cannot absorb overcharge, and when fully charged the charge current must be cut off. A continuous trickle charge would cause plating of metallic lithium, and this could compromise safety. To minimize stress, keep the lithium-ion battery at the 4.20V/cell peak voltage as short a time as possible."

Here is another reference stating: "No trickle charge is applied because the Li-ion is unable to absorb overcharge."

And my original reference at Microchip.com, designers of charging chips: "...it is not recommended to continue to trickle charge Li-Ion batteries.", since you forgot it when quoting me.

Yes, this is the important point here. When the cell cannot accept any more charge, any energy that continues to be applied form the charger contributes to lithium plating.

You're correct, it has been the subject of much research by cell manufacturers and the designers of the chips that implement the charge algorithms in our chargers. They seem to take it pretty seriously.

As far as the relative risks of using 'DX chargers' or hobby chargers, your guess is as good as mine! Unless you have some references you would like to share?

Several of the users realized that the setting was wrong (after the fact).

I think you are mixing different conditions and states since I'm not talking about fully charged cells: at 4.20V the cell can store more energy but if the charge voltage is also 4.20 then there is no "trickle charge" nor any "plating of the anode" because there is no potential difference. There are simply no electrons moving.

There are numerous reports of hobby chargers causing fires while I've seen none reported from using a cheap DX charger (and many of them are sold with more expensiver flashlight brands such as Solarforce or Wolf-Eyeys). All the flashlight incidents i've read about have been from damaged cells (by overdischarge) or by reverse charging.

I use a ball bearing between the spring and battery with mine to charge 14500s, works great. It does take awhile to charge 18650 but my batteries always go green at 4.17 volts everytime. It is such a small charger and inexpensive too, I like it.