Lithium ion cells - Page 1
Forum section: electronics / general

author: rexxar
author_rank: Frequent Contributor
timestamp: March 06, 2014, 11:37:49 pm
content: Hi all. I'm working on a battery-powered project, and I need to buy some lithium ion cells. I'm aware that most of the cells you find on the internet are recycled crap batteries, so I've been very skeptical of everything I've seen so far.Amazon has some 18650 cells that are supposedly Panasonic brand. Any ideas if these are legitimately Panasonic cells?linkIs there somewhere that cells LiIon cells for reasonable prices? Where do you guys get lithium cells from?

author: johansen
author_rank: Super Contributor
timestamp: March 07, 2014, 12:15:52 am
content: here you go:http://lygte-info.dk/review/batteries2012/Common18650Summary%20UK.htmlhttp://www.candlepowerforums.com/vb/showthread.php?330236-Battery-test-review-summaryI do recall someone making the statement that the best cells are sold in a name brand battery pack and you have to buy the 18v pack, or the laptop batteries (6,8,9 cells) to get the cells. i believe they are panasonic, and they are not sold separately.I wouldn't pay more than 5$ per cell unless i knew what i was getting.

author: NiHaoMike
author_rank: Super Contributor
timestamp: March 07, 2014, 02:59:09 am
content: Unless you have a good spot welder designed to attach tabs, get the cells with the tabs already attached. It's very easy to damage a lithium battery with too much heat. The tabs allow you to make the actual solder joints a distance from the actual terminals.Use a soldering iron or gun with plenty of heat capacity, pretin your wires, and work quickly.

author: johansen
author_rank: Super Contributor
timestamp: March 07, 2014, 09:23:45 am
content: that's not true at all.on the positive side, the end of the cell is isolated by isolated fingers extending from the formed seal, the seal itself can hold back 150C or more, depending on the material, it would take a 50 watt iron a minute or so to even get the seal to 150C.......on the negative side, provided you solder from the top down, meaning gravity holds any free liquid (hint: there should NOT be any) away from the solder jointthen there's no chance for high pressure to form. yes, you will vaporize a few micrograms of free liquid stuck to the bottom of the cell, but that's it.the steel container the cells are pressed out of has such poor thermal conductivity, you won't even warm the sides of the cylinder up before the solder joint is complete.

author: nctnico
author_rank: Super Contributor
timestamp: March 08, 2014, 01:28:30 am
content: The problem is that most people mess around with tips and irons way too small for soldering a relatively big lump of iron quickly.

author: tom66
author_rank: Super Contributor
timestamp: March 08, 2014, 01:56:52 am
content: Really wish we could buy cells at the price Tesla pay, less than $3 each for quality Panasonic modified 18650 type, 3.1Ah, 4C peak 45sec/2C continuous.One thing to look forward to: in 10 years time when some older EVs get scrapped, there's going to be a good source of high quality 18650 cells (probably with over 80% capacity remaining if they treat them well like Tesla, not if they bake them like in the Leaf.)There's nearly 8,000 cells in one car...

author: Kjelt
author_rank: Super Contributor
timestamp: March 08, 2014, 11:02:14 am
content: Quote from: tom66 on March 08, 2014, 01:56:52 amUnfortunately car makers have already thought of that:QuoteSo probably the same reason you are not able to buy these batteries now is going to be the same reason you are not able to buy them then. Huge contracts for huge volumes, closed market.

author: amyk
author_rank: Super Contributor
timestamp: March 08, 2014, 02:35:45 pm
content: That's funny, since the Chinese were recycling laptop batteries long before that - and if all the *fire brands are indeed recycled and not new, then there's evidence to say that a lot of the 18650s that get thrown outstill have quite a bit of capacity. Even an 18650 that has only 1500mAh left is still over 5Wh which is more than the best new AA NiMHs (~4Wh). Torches and other devices can still make use of this capacity.

author: tom66
author_rank: Super Contributor
timestamp: March 08, 2014, 02:59:34 pm
content: I imagine (hope) they'll still be a market for crash damaged batteries.In the Model S, there are 16 modules. If one of these is compromised, car will have very short range (*in the Roadster one module failure lead car to go from 240 miles to 30 miles range. )So there hopefully might be a supply of modules from scrapped cars. as repairing/replacing the pack on a car with 100,000 miles is probably not worth it, especially if vehicle has other severe damage.

author: JoeO
author_rank: Frequent Contributor
timestamp: March 08, 2014, 10:47:57 pm
content: Quote from: tom66 on March 08, 2014, 01:56:52 amI have been buying used 18650 batteries for less than 50 American cents each. Just look for used/dead? laptop battery packs.Be very careful opening them up and separating them.Buy a charger and test them. Works for me.

author: amyk
author_rank: Super Contributor
timestamp: March 09, 2014, 09:15:23 am
content: What capacities do you get from them?

author: JoeO
author_rank: Frequent Contributor
timestamp: March 09, 2014, 09:47:06 am
content: The batteries are speced at 2200maH to 2900maH.

author: Rasz
author_rank: Super Contributor
timestamp: March 09, 2014, 06:20:40 pm
content: your best bet is brand cells from reputable sources (like amazon, but real amazon, not amazon resellers)next is ORIGINAL new battery packsnext ORIGINAL used battery packs, even 2 year old sanyo/panasonic cells witll hold >1500mahanything from ebay will be 400-600mah with 5000mah sticker

author: justanothercanuck
author_rank: Frequent Contributor
timestamp: March 09, 2014, 09:35:20 pm
content: I've been hearing a lot of good things about the Sony US18650VTC4. 2100mAh, with a 30A continuous discharge. The price seems to range from $8-12 a piece, depending on where you get them from.