EBIKE BATTERIES.?

Spartacus

Finding my (electric) wheels
Feb 2, 2018
10
3
86
Newark
Hi All. I bought a used Ebay, electric bike four years ago,.36v 250 watt rear wheel motor.. Quite pleased with it. But the lead acid battery weigh:s in at 28 lbs...Ran out of power,8 miles from home.Like pedalling a Sherman Tank?. I am in the process of making a 36 v , li ion cell, battery,approx 1/ 5th the weight. I.will keep you posted with progress.. Regards,,Spartacus
 

Nealh

Esteemed Pedelecer
Aug 7, 2014
19,988
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West Sx RH
You can't come on here make a statement and then just tease us :rolleyes::rolleyes:.

What cells at are you using and configuration ?
How are you building the battery soldering, spot welding or other ?
 

Spartacus

Finding my (electric) wheels
Feb 2, 2018
10
3
86
Newark
Hi I plan on using about 40 used 18650 ex laptop batteries. not sure of the series/parallel configuration yet, further advice needed , I will not be soldering or welding the tabs to each cell, but i hope to rely on compression joints, as i want to be able to isolate each cell for testing purposes. At the moment all the info, layout plans etc are stored in my head:. hope it works okay ? Will keep you posted . I AM. Spartacus.
 

craiggor

Esteemed Pedelecer
Jan 9, 2015
498
171
Hi I plan on using about 40 used 18650 ex laptop batteries. not sure of the series/parallel configuration yet, further advice needed , I will not be soldering or welding the tabs to each cell, but i hope to rely on compression joints, as i want to be able to isolate each cell for testing purposes. At the moment all the info, layout plans etc are stored in my head:. hope it works okay ? Will keep you posted . I AM. Spartacus.
I don't think you will be going far on 40 used laptop cells. Vruzend .com do a nice kit for holding 18650's under compression. New version coming soon. See their website for more info.

Sent from my T1005 using Tapatalk
 

soundwave

Esteemed Pedelecer
May 23, 2015
15,971
6,292
you will have to test all the cells for capacity first as if there under 2000mAh then id not use them.

and as there used from laptops some cells might be a dead short so best to test them.
 
D

Deleted member 4366

Guest
Hi I plan on using about 40 used 18650 ex laptop batteries. not sure of the series/parallel configuration yet, further advice needed , I will not be soldering or welding the tabs to each cell, but i hope to rely on compression joints, as i want to be able to isolate each cell for testing purposes. At the moment all the info, layout plans etc are stored in my head:. hope it works okay ? Will keep you posted . I AM. Spartacus.
Don't waste your time. 40 cells isn't enough. Used cells have massive sag, so you need at least 80 to get a working battery, which will be double the size and weight of a new ebike battery. By the time you've bought the necessary test equipment, BMS and other stuff, it'll be no cheaper either.
 

Spartacus

Finding my (electric) wheels
Feb 2, 2018
10
3
86
Newark
Hi Craiggor. d8veh. soundwave. I am aware of the points you raised. and agree with you, But i am already committed to trying a different battery.I need to exercise my brain cells more, and this seems a good way,so onward & upwards, if this is the last you hear from me,. take it. that i have short fused or blown myself up,and am peddling away with the angels up yonder.. Will put a good word in for all Pedelecs members. Cheers. Spartacus.
 

Nealh

Esteemed Pedelecer
Aug 7, 2014
19,988
8,170
60
West Sx RH
Even though this might be a wasteful effort using old laptop cells the knowledge gained is worth it, esp with wiring a BMS and then being able to fault find issues with future batteries.
Certainly a worthwhile small project to keep the brain cells ticking over and for later if you decide to use better cells.
 

Spartacus

Finding my (electric) wheels
Feb 2, 2018
10
3
86
Newark
Even though this might be a wasteful effort using old laptop cells the knowledge gained is worth it, esp with wiring a BMS and then being able to fault find issues with future batteries.
Certainly a worthwhile small project to keep the brain cells ticking over and for later if you decide to use better cells.
 

Spartacus

Finding my (electric) wheels
Feb 2, 2018
10
3
86
Newark
Hi Nealh. Thanks for your input. i am not using a BMS i am fusing every cell link to the next, and to the bus bar using tinned copper fuse wire. what i am not quite sure of is the wire current rating of each cell to cell, and each 5 parallel cell, pack to pack..any info would be welcomed?. Spartacus.