I’m not done messing with this thing yet. I like a good mystery, and I’m trying to figure out what’s going on before I get all panicky.
I took it outside in a safe dry location and put four Eneloops in it this afternoon. They were only partially drained, from a radio that I’ve been using them in. They are relatively new and have been cycled (always as a set, since new, in a Maha C-9000) perhaps four or five times. They terminated pretty close to way they should, at 1.45 / 1.45 / 1.46 / 1.39.
As soon as I have some 18650s somewhat run down, I’m going to try it again. I don’t remember for sure, but I think both of the termination anomalies involved the left-side slot #1. I want to see if the problem repeats itself, when I’m home and free to watch it closely. I’d like to do a set of 4, at 0.5 A in all the slots, and then a pair using slots 1 & 4 at 1.0 A.
The ‘scorched electronics’ smell does seem more pronounced after charging the Eneloops. I guess I just want to make sure this wasn’t an isolated incident, and I want to make sure it’s the chargers fault and not the fault of a cell, or operator error of some kind. Finally, I don’t want to be slagging Xtar unfairly. To that end, I’m almost regretting opening my mouth in the first place. I should have done further tests before posting here. There are a whole lot of folks out there using these chargers with obvious satisfaction.
If it catches fire or a battery goes ballistic, then I’ll feel justified in addressing the matter with Xtar. Either way I’ll post what happens when I get to that point.
Is US based XTAR Direct an arm of XTAR or just a distributor?
If there is a problem you would think XTAR would be pretty keen to get their hands on this charger to see if it’s an isolated issue or if there could be a problem with an entire batch. Nothing destroys a companies reputation like a series of fires.
The Eneloops were fresh off the charger, where they had remained for <\ 15 minutes after termination.
I think mine come off the Maha at about 1.48 as well, and usually quite even. The 1.39 cell was noteworthy, but at least nothing was dramatically out of line. None of them got more than modestly warm.
I should note that the VC-4, prior to this and with its first use, did charge a pair of older Trustfire ‘flame’ 26650’s and four brand new Vappower IMR 26650’s in a normal fashion. That was a month or so ago, but I don’t recall any anomalies. The ‘Flames’ have been unused since, and I just tested them at 4.11 v. (I do hope that name is not prophetic!)
I’m curious - does anyone else’s VC-4 have a quite a strong odor? I’m not sure if this is frying resistors I’m smelling or if it’s natural. Give your VC-4 a snort for me please, and let me know. This one is pretty pungent, and I think it’s worse after charging the Eneloops.
I got 2 LCD failures out of my 40pcs purchased this year. I have already forwarded my findings to vendor and received full refund for them. I did open them up for visual check but found nothing abnormal (e.g burnt components) this time.
Pretty much useless warranty because it will cost more to ship to China than the charger costs. Xtar has really disappointed me with their warranty service which is basically nonexistent. Currently have 13 Xtar chargers but only 4 have been used. Two of those four have stopped working, 50% failure rate. Buy a different brand, one that will last.
4.17v is great in my opinion. I did some tests with my hobby charger and the difference between 4.2 and 4.17 was only about 3% if I recall correctly. From what I understand the batteries will last longer and be happier when charged to < 4.2.
Can’t help you with the smell, it may just be burning off some residue from the manufacturing process, how old is the charger?
As for only charging to 4.17 volts, it’s GREAT for the batteries. As I understand it, the closer you get to max capacity per charge, the shorter the life of the battery. The flip side of this is that the less MAH’s stuffed into the batteries, the sooner they need to be charged. It would be an interesting long term experiment to see where those two graphs intersect. Number of lifetime charges vs hours of useful output vs end voltage.
hmmm, lets see, I’ll need a sponsor, a fleet of batteries, a fleet of chargers with precisely controllable end voltage, a couple dozen identical flashlights… Should probably have them all in integrating spheres to watch the light output…
I think I might have a related problem. I’ve bought a new Xtar VC4 and went on to charge 1 AA (I don’t remember the brand) that usually holds 1600 mAh, as tested with my other charger, the Opus BT-C3400.
The thing here is that the charger keep charging the battery until about 4600 mAh were show in the display… I was afraid it was going to blow away! The voltage was at ~1.45 but it kept charging and charging (the battery was very hot).
I left the charger working in a safe spot, went to sleep and found out the next day that it stopped around 4600 mAh @ 1.5 v. Should I worry about it? How could it be possible that it putted that much mAh into the battery and it didn’t blow up?
Please let me know what you think; thanks in advance.
BTW, it was a battery that started with the “0v revival function”, i.e., other smart chargers (as the Opus) wouldn’t even recognize it because of the low voltage that it had, so I used this function from the Xtar to charge it. I don’t know if this would have anything to do with it.
if i were in xtars shoes i would want to know RIGHT FN NOW! if i had a bad batch of chargers that would replicate the samsung note 7 fiasco so i could recall them,pull off the shelves and get them all back.
but thats just me.
on the good side you have to really overcharge a high quality modern cell to get a nasty outcome.like 12v
iirc thats one of the ul tests.
with whateverfire grade cells all bets are off.
Yeah, there’s source voltage, there’s the load, and there’s a series resistance in-between to limit the current.
That’s why you can take a 9V battery, 3V LED, and 1kΩ resistor, and get only 6mA through it. The voltage across the LED will read 3V, and the resistor will drop 6V.
Same like float-charging Pb-acid batteries. They’ll soak up (depending on their size) a certain amount of current without increasing their voltage, so you can hit ’em straight from a 24V bell transformer (and diode, etc.) with only an appropriate-value series resistor, and they’ll safely float away for their full service life without a hitch.
That’s why I like those cheapo 2buk chargers FT sells, because they’re so low a charging current you’d really have to leave them in for days on-end to hurt the cells.
A fast-charger, of course, needs to be WAY more critical in its source voltage.
One suggestion, or at least something on my “wish list”, is to have an option to charge a cell to only 90% capacity, for longer life at the expense of runtime.
Charging to only 4.1V (or 4.0V), say, would also leave more “headroom” in case of overcharge.
Before all dogpiling on XTAR , let’s wait to hear back what their customer-service says.
I got a WK50 with a bit of a wonky switch (only intermittent problems), contacted the vendor to see if they had just a replacement switch to send, vs snailmailing everything back’n’forth, and was told to keep the light, they’d send me another (it’s on the way!), and even sent instructions with pix as to how to take apart the tailcap and play with it myself to have 2 working lights. I was sufficiently wowed.
Absolutely, it’s in XTAR’s best interests to get back the charger and find out what went wrong, even if they have to eat the cost of return postage. A few bad incidents of Li cells going supernova would make XTAR chargers the equivalent of Galaxy phones. Forget recalls (shady sellers would keep selling them anyway). What they’d lose in terms of sales just from BLFers would be probably hundreds of times the cost of the return postage.
I kinda get the feeling that one of their distributors in Canada would realise this and offer to cover return postage.
