18650 li-ion cell source?

[Haku]

In a few weeks time I hope to have enough money to buy a bunch of 18650 li-ion cells to re-cell one of my ebike batteries, I intend to build a circuit before I get them so I can do charge/discharge capacity tests to match cells when putting them in parallel and weed out any 'bad' ones.

Does anyone have any suggestions of reliable places to buy them in bulk? with tabs already on as I don't have the necessary equipment to spot weld the cells.

There's some nice deals on eBay for UltraFire cells in bulk but reading around the web it appears anything advertised above 3000mAH is most likely fake, as in re-badged unknown cells with random capacities, certainly not something I'd like to put into a bike battery.

 

[jerrysimon]

The cost of these genuine cells seems a lot. Is it really worth it plus the hassle of re-celling ?

Ps I thought these were the Headway cells so maybe not as expensive. Even though presumably you are going to builld a larger 36V 9Ah battery you will need a lot which is quite a bit of work including a BMS to protect it all.

Could you retro fit a Ping battery ?

Regards

Jerry

 

[jerrysimon]

PPS Might be worth reading this. Looks like they are only any good for 1C.

Endless-sphere.com • View topic - Building a 48 Cell 18650 Li-Ion Battery Pack?

Regards

Jerry

 

[Haku]

I don't have a lot of money but I do have electronics knowledge and spare time, plus the 26v pack I intend to re-cell is designed such that it appears pretty straightforward to replace the 28 cells as they're all mounted in two plastic holders specifically designed to hold 15x 18650 cells.

Plus if all goes well it means the further idea of building a special pack for my Urban Mover UM30 (where the battery pack is long and thin and fits inside the frame) looks very likely to happen.

 

[jerrysimon]

Ok keep us posted, as I would like to see how it works out

Regards

Jerry

 

[Deleted member 4366]

There's lots of different types of 18650 cells with different capacities. The ones that I have range from 1000 to 2250maH. Naturally, you want the ones at the top of the range because it gives more capacity for less weight. I got mine (enough for two 10aH 36v batteries plus convert every torch/searchlight and bike headlights etc to lithium power) from laptop batteries. They sell job lots of used laptop batteries on Ebay I got two lots for about £50 including postage. Nearly every cell was OK, but there's a lot of testing (charging and draining to figure out which are the best ones. If you go this route, look out in particular for Toshiba batteries, which have nice Panasonic cells - mainly G5s an G7s that are 2000maH.