Are these batteries good? Seems cheap for an 8 amp-hour Li-Ion battery. You get two for $7.77 plus $2 shipping, or maybe $5 apiece..
DESCRIPTION: Quantity:2 Standard voltage is 3.7V, the voltage of full charge & empty condition is 4.2v & 2.5v respectively Particularly suitable for flashlight, electric tools, electric bicycles, electric vehicles Capacity: 8000mAh Voltage: 3.7V Material: Li-ion
They lie. The very best 26650 Li-Ion are the Panasonic NCR cells, which are about 5000mAH. The Ultrafire cells would be typically 1/3 of that, or 1600mAH. Likewise all the other *fire Chinese brands (TrustFire, SureFire, CatchOnFire, etc).
Furthermore, there's a whole industry repackaging dead cells scavenged from old equipment.
On a sunny day (Thu, 19 Nov 2015 01:46:11 -0800) it happened mike wrote in :
Well I really do not know,
2 years ago I posted this here
$3A$209V$20Battery$20or$202$20x$20AAA$20with$209V$20Converter|sort:relevance/sci.electronics.design/DbgPnYXfGcY/KndUBmUUj7AJ (scroll down, it says:): " here one of my flashlights, with battery out:
Li-ion, rechargeable, 3.7V 3.2Ah, LED, has several brightness stages, flashing mode too, came with charger. I have several smaller Cree ones, those all have Eneloop AAA those, and will still work a year after charging. All ebay stuff. The big Cree has as defect that it melted the plastic around the LED when I left it on to test how long the battery lasted. Now the beam looks a bit different... " So it delivered a real amount of power for a long time, the flashlight melted, the batteries are still OK. Fixed the flashlight, it was not properly assembled.... So far I have no complaints. Since I took out the spare utra-fire battery just now, I am recharging it in all by itself in that 2 x charger you mention and that is still on. No smoke from that area yet.. It was at 3.85 V, but OK..
Yes, sure I read those stories in the news of people getting burned to death or something using Li-ion or whatever... There is one in every laptop? Batteries is a consumable, I have plenty more problems with lead acid, be it sealed or just normal car batteries, than with these Li-ions or lipos.
It is important that the flashlight works for a reasonable amount of time if you have not used it. Since I DO use it more often .. I dunno, but this spare battery I am charging now was still near almost? full, and that was a bad one.
I have eneloops in a smaller LED flashlight, those work OK too, and are used several times a day, for example for inspection of stuff.
If yer life depends on it, then you need to keep several flashlights maybe with several battery technologies, a fire maker, drinking water, gun to shoot deer, and of course your cellphone to call for help.. ;-)
I do not normally buy at flee markets.... ebay is much better.
And that is my experience.
Maybe somebody should measure discharge times.... Maybe somebody has.
Still it may be different for different batches / sources.
Someone who claims to be into technology should be able to quote more than one level. Most of this stuff is a repeat of its prior post.
Jan Panteltje wrote in news:n2kb4r$dcb$1 news.datemas.de:
> Path: eternal-september.org!mx02.eternal-september.org!feeder.eternal-september.org!weretis.net!feeder4.news.weretis.net!newsfeed.datemas.de!news.datemas.de!.POSTED!not-for-mail
You need to exercise extreme discretion. Think "brand-name" and "reputable seller". That is a no-brainer when buying such items from Fleabay. Even so when buying from Amazon, Amazon allows counterfeit sellers left and right.
Yes, that seems about right mWH instead of mAH. I went shopping at Fry's today and couldn't find any LI batteries over 2500mAH and they were 12 bucks each. I did see a new item I hadn't seen before. A 10,000 mAH 'D' NiMh cell for 10 bucks. It was in a package of 2 for $19.95. But I already have several 4000 mAH Ni-Cad 'D' cells that still work. I see a lot of used cell phone batteries at swap meets for $1 each, so I could parallel 2 or 3 to get a higher capacity. . . .
I mistakedly bought a couple 18650 Ultraf*re batteries- far less than marked capacity- I dissected one- it was not a used cell, just poorly made and significantly lighter than a good one from a reputable manufacturer.
It's kind of interesting when you open them up- the energy is still in there, of course, and bits will spark and smoke when you breach the film separator barrier.
It looks like there was once a valid UltraFire source that was either compromised or cloned up the wazoo. Prices don't look unreasonably low for some offerings, by chemistry and size but the mAH ratings are off the wall - might read as WHr - would make more sense.
When the polymer protective layer breaks on an internally protected cell contact (permanently), there's often energy stored in the dead cell. The protection method wass unpopular, as the polymer seemed unpredictable with age and environment, producing premature opencircuits.
On disassembly, this remenant can result in spontaneous combustion.
I disassembled these things under water, when I had to. Once a useful source of plated stamped copper mesh. I'm not so sure all that free lithium is good for you, unless prescribed by local MH Professionals.
On a sunny day (Fri, 20 Nov 2015 09:04:58 -0800) it happened Jeff Liebermann wrote in :
Wow, did not know about that site. Sure, from the spelling on the battery it is clear you are not dealing with a real multinational:
But, it gets the work done, if it was made of chewing gum and kept my flashlight working I would be happy too, even if it had only a picture of Mickey Mouse on it.
I get many things from China that look like 'home made', for example the 1 Ah lipos with Varta on it, I am still not sure it really _is_ Varta, but... 300 charge / discharge (90 %) cycles later I see a slight decrease in capacity. reasonable for a lipo...
Its just a consumable... Because I did see that decrease, and these need to run 12 hours a day, (now talking lipo) I bought some of these power packs to test:
I still have to solder these in... It is actually these:
These ones have _no_ protection unlike the Varta marked ones, so BIG currents may flow. So... 25 A discharge? Will see, will likely add a fuse.
What you are probably buying are 1000 ma-hr 18650 cells marked with whatever the vendor thinks will sell. The cell is good enough for most things, but not if you're trying to squeeze every last coulomb out of the cell, as in quadcopters or flashlights. They're probably just fine for your instrument experiments, eBikes, and vapo-smog generators. I'm not sure about the number of charge cycles on these batteries. It's my understand (possibly wrong) that cell design can optimize capacity or charge cycles, but not both.
At 90% discharge, you should be killing those batteries. At what terminal voltage do you stop brutalizing those batteries? See Fig 2:
10% would be about 3.50V.
For extra fun, run a frequency scan of your LiIon battery and watch it age: I haven't done this but plan to throw together something to do it, some day, later, maybe...
Money is also a consumable. Whatever works for you, as long as it doesn't become a collectable, which is responsible for my mess.
I use similar batteries, mostly those used by the RC community. This is my favorite 11.1v battery pack: Yes, I pay extra for the shrink wrap, power connector, balance charging connector, but don't want to build battery packs (until I get spot welder).
The aformentioned favorite 11.1v battery is rated at 25C continuous discharge: 25 * 2.2A = 55A with a maximum charge rate of 5C or: 5 * 2.2A = 11A You might as well use a PCB trace as a fuse. However, you can get chargers with overcurrent protection: 3S, 4-5A 3S, 10-15A
Jeff Liebermann email@example.com
150 Felker St #D http://www.LearnByDestroying.com