3.7V Li-Ion Battery has Built-In Protection Circuit? - Page 1
Forum section: electronics / general

author: Mechatrommer
author_rank: Super Contributor
timestamp: June 06, 2013, 01:22:03 pm
content: i bought one non-working batt that i thought was working. and then this "built in circuit" print out got me interested since its just a battery, so i made a "nonreversing" teardown....this "UltarFirc battery"... built-in circuit my chinese arse!

author: tom66
author_rank: Super Contributor
timestamp: June 06, 2013, 01:38:26 pm
content: "UltarFire"!It's always got non-obvious reasons for fire.On the plus side you've got some lithium which will be fun to play with in a bowl of water.

author: digsys
author_rank: Unknown
timestamp: June 06, 2013, 03:21:00 pm
content: There are a LOT of sad stories about the UltraFire Lithium batteries. I bought the M20 X-Warrior CREE LED Torch kit,and it has the exact same batteries !! (checking them now). The torch itself is great, but I worry about the chargeralso. EVEN though I scoured the Forums and bought the kit based on user comments. I'm sure there's even worse out there !

author: Mechatrommer
author_rank: Super Contributor
timestamp: June 06, 2013, 07:22:53 pm
content: Quote from: tom66 on June 06, 2013, 01:38:26 pmi dont know. just tried it. there are black matters, tin foil and copper like foil, put a small amount of everyone in water, nothing! i guess the black matter is recycled gunea pigshit or something. back to the bin.Quote from: digsys on June 06, 2013, 03:21:00 pmi spotted my other 3 "imitation" batteries that are poorly performing. one is more "legitimately spelled" UltraFire, and one is "Bluebaby" and another one is "Tomo". all with the claimed "built-in protection circuit". i'm really into bad section of electronics, or am just learning new lesson. what a waste.

author: BravoV
author_rank: Super Contributor
timestamp: June 07, 2013, 01:15:29 am
content: Just don't understand why whine and complain if you already fully aware that you've bought cheap junks, it is still a garbage no matter how they labeled it or how you're expecting it, and consider you're lucky they didn't burn down your house or exploded straight at your face.Next time, save a bit of money and buy only top tier cell like a genuine panasonic brand, and from now on stop buying these re-labelled junks like those "Bluebaby"or "ULTRA-crap" or "shitty-FIRE" thingie.Examples of these Panasonic cell photo assuming that you've never seen one, again, although these cells look ugly compared to those crap-fire thingy and without those bling-bling label or cool name battery of yours, you will be amazed how these cells perform.

author: iloveelectronics
author_rank: Frequent Contributor
timestamp: June 07, 2013, 01:27:12 am
content: The funny thing here is that "UltraFire" on its own isn't even a legit brand, meaning there isn't even a "genuine" Ultrafire brand yet there are all these misspelled "fake" brands like "UitraFlre" and the above mentioned "UltarFirc"

author: jh15
author_rank: Frequent Contributor
timestamp: June 07, 2013, 01:32:41 am
content: Live long and prosper, you have a long sheef life ahead.

author: westfw
author_rank: Super Contributor
timestamp: June 07, 2013, 05:04:32 am
content: QuoteSo where do you recommend that one BUY these genuine panasonic protected cells? It seems that the "respected" manufacturers won't sell such things through normal low-volume distributors, with or without"protection circuits", and I have little faith that the eBay and Nth party battery sellers are selling real panasonic cells, even if they claim to be doing so...

author: IanB
author_rank: Super Contributor
timestamp: June 07, 2013, 05:52:38 am
content: Quote from: westfw on June 07, 2013, 05:04:32 amI believe that some of the retail suppliers like AW and Redilast do have good quality original cells. They have been independently tested and found to perform within expected parameters.

author: IanB
author_rank: Super Contributor
timestamp: June 07, 2013, 05:57:22 am
content: Quote from: Mechatrommer on June 06, 2013, 07:22:53 pmThere should be no metallic lithium present in a normal lithium ion cell. It is lithium primary cells like the CR123A that have actual lithium metal inside them (but those cells are also like mini-grenades, so don't mess with them unless you know what you are doing).

author: tom66
author_rank: Super Contributor
timestamp: June 07, 2013, 06:56:31 am
content: Very similar Panasonic NCR18650 are used in the Tesla Model S.

author: Mechatrommer
author_rank: Super Contributor
timestamp: June 07, 2013, 12:08:15 pm
content: yes i just bought whats given locally. after several cycle of buy and test, i asked for the more expensive battery, its the "Bluebaby" @ ~$9 a piece, thats all they got. i still doubt it can deliver the 3AH as printed. one day i will struggle and insist on the "original" brand, one day.

author: amyk
author_rank: Super Contributor
timestamp: June 07, 2013, 01:22:42 pm
content: It's hilarious how they're making clones of already low-grade brands... UltraFire (the real one) and the other *Fire are still mostly just relabeled recycled cells."Bluebaby"!? As if the *Fire complete with flame-based logo imagery wasn't ironic enough...

author: uoficowboy
author_rank: Regular Contributor
timestamp: June 07, 2013, 08:05:08 pm
content: A couple things to note here:It looks like you sawed into the side of the case to open it up. That really is not necessary - you can just pry apart the crimped end (+) of the cell.I've never seen an 18650 cell with a built in protection *circuit*. I have seen one or two that had a PCB sitting on top of the cell and then shrinkwrapped to make it look like it was a part of the cell. But I've never, ever seen circuitry inside one. Not that it would be impossible - but I simply have never seen it. This page:http://www.lygte-info.dk/info/battery%20protection%20UK.htmlshows some cells with external circuits.However, most 18650s do have a couple protections built in to them. Specifically - a CID and a PTC. The CID (Current Interruption Device) is essentially two pieces of metal spot welded to each other. During overpressure conditions inside the cell they spot weld breaks, permanently disconnecting the cell from the outside world. The PTC is a small resistor in series with the cell that will heat up during high current loads and cause the output voltage to drop. It of course is not a permanent change. These two parts are good for overcurrent/short protection. Not exactly a circuit, but it could be argued that that was what the label was referring to.

author: Mechatrommer
author_rank: Super Contributor
timestamp: June 08, 2013, 08:23:42 am
content: Quote from: uoficowboy on June 07, 2013, 08:05:08 pmpryting + tab wont get me in there, it will only make a small opening. the metal shell is spot welded on the + side end, worst.. "circumferenced welded" around. i looked carefully before making the autopsy, this is a one way ticket design. sawing is the easiest way. the fun of it was that, the shell got hot when i sawed it, i guess some short circuiting to the body happened.Quote from: uoficowboy on June 07, 2013, 08:05:08 pmcontradicting and confusing statements.thanks for the link though, good info.

author: Neilm
author_rank: Super Contributor
timestamp: June 08, 2013, 09:01:55 am
content: Quote from: Mechatrommer on June 08, 2013, 08:23:42 amNo they aren't. The 18650 does not have a protection *circuit* (by which I mean FETs, Ics and the like). However, within it's construction it has certain features that offer a degree of protection in fault conditions. For instance, the cell is designed to go open circuit in the event of it getting too hot. This is a single shot protection system that is designed to work as a last resort.The protection circuits are there to help prevent overcharging, over discharging etc. These are designed to disconnect the output in fault conditions and can be reset.Neil

author: Mechatrommer
author_rank: Super Contributor
timestamp: June 08, 2013, 11:25:36 am
content: yes my mistake, i was too obsessed with *circuit*

author: uoficowboy
author_rank: Regular Contributor
timestamp: June 08, 2013, 06:28:22 pm
content: Quote from: Mechatrommer on June 08, 2013, 08:23:42 am18650 cases are not solid. They have two terminals, separated by a small bit of plastic. You pry at that separation point. I like using old heavy duty wire snips. I've dissected maybe 40 or so 18650s, and this technique has never failed me. Much easier, and much less likely to damage the guts.I'm not sure what was confusing, and it's definitely not contradictory - there is no internal circuit, but there is a system for protecting the cell from *some* faults.

author: SeanB
author_rank: Super Contributor
timestamp: June 08, 2013, 07:10:40 pm
content: There are designed in overpressure rupture points and disconnects to open circuit the cell (permanently and with some deformation of the case) if overcharged or overtemperature, but these are only there so it does not actually explode in failure or go short circuit.There are some entertaining tests done on the cells, involving using a nail gun to shoot a steel nail through a fully charged cell to short it out, and it must not catch fire during the resulting venting.

author: IanB
author_rank: Super Contributor
timestamp: June 08, 2013, 07:19:03 pm
content: Quote from: SeanB on June 08, 2013, 07:10:40 pmI think that's pretty unlikely with LiCo cells. There is a flammable organic electrolyte and lots of heat caused by the short circuit (if you punch a nail through the middle of the cell the short circuit protections will be bypassed). Heat plus flammable vapour equals flames.

author: uoficowboy
author_rank: Regular Contributor
timestamp: June 08, 2013, 07:41:34 pm
content: Quote from: IanB on June 08, 2013, 07:19:03 pmSome cells are designed to handle it gracefully. A former employer's cells were among them.Not to say they didn't get hot as hell - but they were designed to not catch fire.