Tmart's deal of the day: http://www.tmart.com/ShopWays/Daily-Deals.html They don't look protected but at 2 for 5 bucks, not a bad deal if you're looking for some spare cheapies for those lights you dont' use often. I ordered 4, not much of a risk at this price...and for US buyers, ships from the US warehouse.
Some users here are saying to always keep away from UltraFires...
I would not take those if they were free. They are most likely used, rerun, recycled, worn out cells. Fire and explosion lottery tickets with poor performance until then.
This is why I listed this as a possible deal...I know they're not always the best but they're definitely cheap.
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No one is mad at you, but it is important to avoid Ultrafire cells...
Here is a link to a thread at our beloved sister forum:
http://www.candlepowerforums.com/vb/showthread.php?280909-Ultrafire-18650-3000mA-exploded
I have some of these and they Push upwards of 4A to my C8 XM-L's!, but I only paid 3.99 a pair, also at TMart. Here is the current link. To those that pooh-pooh cheap batteries, let me ask you, is better to spend a lot and get screwed, or pay a little and get screwed. I really don't have much confidence in ANY of the batteries.
http://www.tmart.com/2Pcs-37V-3000mAh-UltraFire-18650-Liion-Rechargeable-Batteries-Red_p143123.html
I would rather spend more and not be injured.
3000mAh, my @$$!
I understand your point,
I have no way to measure the mAh capacity of the batteries I buy. I realize there is no such thing as a 3000mAh cell for $2, but I also know that most, if not all cells are over rated.
I mentioned that these cheap 2/$3.99 cells deliver upwards of 4A to my C8- XM-L's. What this means to me is that they are of very decent quality, not garbage. The reasoning on my part is that they must have rather low internal resistance to be able to deliver that kind of current. I have other so called "better" cells that will not deliver as high a current.
If one were to put 2 cells in parallel, one would double the mAh rating of the combination. Also the internal resistance would be cut in half (the 2 internal resistances of each cell in parallel). Therefore I assume that internal resistance of a cell is an indirect measure of the relative mAh capacity of that cell.
There is a correlation between internal resistance and mAh capacity. In fact one way to look at the effect of discharging a cell is that as it discharges the internal resistance increases.
Not directly, it is more depend on the battery construction. A battery designed for high current drain will have a low internal resistance (Check AW 1600mAh).
The internal resistance does not change much with charge condition (As can be seen on the trip test chart in all my battery tests), but does change with age/usage.
The point is that it only takes one bad battery for something bad to happen. I realize there have been a million 18650 batteries of the worst sort sold to people on ebay and with package deals or whatever. There have been very very few reports of anything bad happening. Also, probably part of the reason these high powered lights haven't gone mainstream is that people buy these off ebay and get crappy batteries that run for 5 minutes and dismiss ever buying again because it's chinese junk.
Anyways I'm just saying even with AW batteries there's a chance of failure, but these cheap Ultrafire (especially these exact ones with know failures) are just asking to burn your charger, or explode in your light. Don't buy the Pinto because it's cheap when it might blow up! At very least don't run them in multi-cell lights in series.
Hey, I liked my Pinto...what's the risk there anyway?
HJK - Would you say though, all things being equal, that a lower internal resistance is at least an indication that the battery is NOT of poor quality, or worse recycled? The point I was trying to make is that in this environment (Chinese sellers) You can get less than you pay for. It is also possible to get more than you pay for.
My mantra concerning purchases where I do not have all the facts is "Buy cheap and figure it out later"
As far as safety is concerned, I do NOT trust and of these cells and act accordingly.
If the battery has high internal resistance it is old or bad quality, but you cannot assume that a low internal resistance means good quality.
Batteries like the Panasonic 2900/3100 are very safe.
The NCR’s specifically, due to HRL?
Or you mean that generally proper brand-name cells are very safe, not only NCR-based cells, but also Sanyo cells, Samsung cells and others?
Yes.
I do mean that proper brand names are safe, but the HRL increases that safety.
The brand names does a lot of safety test on their LiIon batteries, but in the descriptions I have seen they do not repeat stuff. I.e. the battery can safely be discharge to 0 volt or even reverse polarity, but do not try to charge them afterwards.