<$2.50 18650s? Cheapest cells per Wh?

[TomCasalino]

I need help on finding cells for a new battery back for my 36v bike. I am currently using a 10s4p pack comprising of recycled laptop batteries that only have an average capacity of ~800 mAh each (the entire pack is about 3.2Ah, 36v nominal). This setup only gets me about 3-4 miles before I hit LVC, and I am looking for a solution for a much longer range, preferably 20+ miles per charge. what would be the cheapest way to accomplish this goal? I would prefer to use only new cells, as recycled laptop battery cells vary greatly in capacity and are generally not very pleasant to work with.

 

[riba2233]

These are cheapest per capacity but low C rate

http://eu.nkon.nl/rechargeable/18650-size/samsung-inr18650-29e.html

http://eu.nkon.nl/rechargeable/18650-size/samsung-icr18650-26j.html

http://eu.nkon.nl/rechargeable/18650-size/panasonic-ncr18650b-made-in-japan.html

 

[redilast]

What motor wattage are you using? Any idea about your Wh/mile? 20+ miles on a 40 cell pack might be a bit tricky for $2.5 per cell.

 

[999zip999]

Some vendors offer 3 spot welded in parallel cells. This way you have something to solder to 2 Series them. Or do you have a spot welder ?

 

[randyc1]

These are cheapest per capacity but low C rate

http://eu.nkon.nl/rechargeable/18650-size/samsung-inr18650-29e.html

http://eu.nkon.nl/rechargeable/18650-size/samsung-icr18650-26j.html

http://eu.nkon.nl/rechargeable/18650-size/panasonic-ncr18650b-made-in-japan.html

Hey Riba !,... and which would you recommend that are Not cheap for e-bike or e-skate ??

 

[TomCasalino]

What motor wattage are you using? Any idea about your Wh/mile? 20+ miles on a 40 cell pack might be a bit tricky for $2.5 per cell.

Im using a cheap ebay "conversion kit" that is advertised as 500 watts. No idea on Wh/mi

 

[riba2233]

I would recommend Panasonic PF, they are best value considering all factors (cost, capacity, current, cycle life, quality... ), and samsung 29E holds second place.

http://eu.nkon.nl/rechargeable/18650-size/panasonic-ncr18650pf-3-7v-2900mah.html

 

[randyc1]

I would recommend Panasonic PF, they are best value considering all factors (cost, capacity, current, cycle life, quality... ), and samsung 29E holds second place.

http://eu.nkon.nl/rechargeable/18650-size/panasonic-ncr18650pf-3-7v-2900mah.html

I'm confused , ....thought cells like SAM 35E,..Sanyo GA, ...LG hg2 were among the best ?

 

[riba2233]

Yeah, but not for cost per wh! They are best for other things like energy or power density, but not cost. Although they are dropping price nicely

 

[randyc1]

Yeah, but not for cost per wh! They are best for other things like energy or power density, but not cost. Although they are dropping price nicely

What do you think about the Samsung 30Q ?? 15A continuous. ?

About 3.00$ on Alibaba ?

 

[atarijedi]

Yeah, but not for cost per wh! They are best for other things like energy or power density, but not cost. Although they are dropping price nicely

LG INR MJ1s are pretty cheap, 3500mAh, 10A max continuous.

 

[riba2233]

Yeah, but not for cost per wh! They are best for other things like energy or power density, but not cost. Although they are dropping price nicely

What do you think about the Samsung 30Q ?? 15A continuous. ?

About 3.00$ on Alibaba ?

That's too low, probably fake ad. They are still relatively expensive compared to others I've mentioned. MJ1 are fine if you can afford them, but still at least 4$ a cell.

 

[randyc1]

Yeah, but not for cost per wh! They are best for other things like energy or power density, but not cost. Although they are dropping price nicely

What do you think about the Samsung 30Q ?? 15A continuous. ?

About 3.00$ on Alibaba ?

That's too low, probably fake ad. They are still relatively expensive compared to others I've mentioned. MJ1 are fine if you can afford them, but still at least 4$ a cell.

...I just find the MJ1 a little lacking in Amperage for a 4P or a 5P pack?

 

[riba2233]

Depends, I doubt that you are going to have 30 A continuously, so 5p shouldn't be a problem. If you are, 6p is fine, and 5p is ok for 25 A continuous.

 

[randyc1]

I think going uphill on a e skate would pull more than 30A ?

 

[flat tire]

Don't think in terms of price per battery, think in terms of overall cost for a pack of your desired capacity.

I think the 30Q would be competitive, especially ordered from China. It also has a decent discharge.

 

[Joe T.]

Yeah, but not for cost per wh! They are best for other things like energy or power density, but not cost. Although they are dropping price nicely

I think once you add your time to build the battery pack the cost of the cell is much smaller than your time. I would want the most miles.

 

[LyonNightroad]

Some vendors offer 3 spot welded in parallel cells. This way you have something to solder to 2 Series them. Or do you have a spot welder ?

Who!?

 

[LyonNightroad]

Yeah, but not for cost per wh! They are best for other things like energy or power density, but not cost. Although they are dropping price nicely

I think once you add your time to build the battery pack the cost of the cell is much smaller than your time. I would want the most miles.

Also, If you don't need the C rate and are willing to build a big enough pack to make the C rate irrelevant (10p could do 60 Amps) you can't beat the Panasonic 18650B

 

[Hillhater]

^^^??? Sure !, that would give you a work around for low cell performance....but you are also losing the advantages of low weight and pack size that are one of the prime advantages of 18650s.
And then you also have to redo the $$/Whr, and $$/kWhr, calculations to see just how much $$s you actually save !

 

[BeachRider2016]

i used recycled laptop batteries, samsung cells 26F, costing at $.70/each cell with 2400mah capacity. Theyre max at 2C discharge but since i got atleast 10cells in parallel, thats 24Ah, theyre never get that high discharge rate. The pack easily last 40miles. Sure its a few pounds heavier but saving a bunch of money recycling cells than new ones. Try searching Ebay and bid on a 45 pack dell laptop batteries, theyre just old shelf stock batteries with almost no usage. Charge em up and good as new. Cant beat 70cents per cell.