How many 18650s will I need for this kit?

[hapc]

Hi, I'm new to the whole Ebike world, specially to building a ebike battery (My ultimate purpose), I'll have more questions anyway.

Well, I want to and probably will buy this kit:

http://www.ebay.com/itm/151911186485?_trksid=p2055119.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT

How many 18650 batteries would I need to keep it running? I think I need more than 10 since I need to cover those 48v (3.7v x 12 or more), am I right?, and what about the Amperage?

Because I've seen some 100 cells battery packs, could I add all of those at once?

I guess that's all for now

Thanks!!

 

[Hillhater]

Hapc , ..welcome to the forum,..you will gain a lot of info here.
Battery building is not simple, read some of the other threads on this forum.
To run that 48v, 1000W , motor kit, you will need a 48 volt battery, able to supply 20+ amps..
So that means at least 12-13 cells in series for the voltage, but then to be able to supply those 20+ amps you need to parallel up enough cells to comfortably support that current, and provide capacity (Ahrs) to give the run time (range, miles) you want to ride. That is dictated by the type and capacity of cell you choose.
For example, a good cell like the Samsung 29E has a capacity of 2.9 Ahr and can output 8 amps for about 20mins.
So you would need at least 3 of those in parallel (39 cells total) just to ride for 20 mins or so.....not ideal !
Typically, you should be looking at a pack of 13 series and 7 or more in parallel for a 20Ahr total, 48volt, pack..
Note , different cells all have different capacity and discharge rates so careful how you choose.
Not all 18650's are suitable for Ebike packs.

 

[hapc]

I see!, that's some good info, I'll try to read more about it, thank you!

 

[DAND214]

Save you a lot of time and money, look here http://lunacycle.com/52v/ or http://lunacycle.com/batteries/packs/48v-20ah-lithium-polymer-battery/
Eric has great prices and great support.

Dan

 

[dogman dan]

Start with the motor kit. It will have a 25 or 30amps controller. So your pack must be able to put out at least 30 amps.

So lets take the example of that cell in the post above, that's able to put out 8 amps. You'd need three in parallel to add up to 24amps. So preferably 4 cells in parallel to have enough oomph to run that 30 amps controller. So 4 cells is going to be 4.2v, able to put out 32 amps.

Then you need to add more cells in series connection, 13 groups of 4, or 14 groups of 4. You need about 60 cells, including a few extras.

If the cell you chose could only put out 4 amps, a lower quality cell, then you'd need around 120 cells to even get started.

 

[999zip999]

I have some cells what does that mean ? If you don't know what you have it would be best to buy a ready made pack that's plug and play. The battery most match.

 

[Skalabala]

Always go overkill on battery. 60 cells are not enough, you will run into problems real soon.
You need about 130 cells for 13s 10p of 29E And about 200 of a lesser discharge capability cell.
Then you can mod the controller also when you get bored and the battery will handle the currant

 

[dogman dan]

60 of the very best cells is what I said. He'll need many more if they are only 2c rated stuff. I would guess he has the shit cells.

But yeah, much bigger is totally best. I rarely ride around with less than 1000 watt hours myself. (48v 20 ah)

 

[Skalabala]

Like MJ1 cells Yeah that will be a nice battery!

 

[wesnewell]

It all depends on the cells you have.With 1C rated cells, you'd need a 26ah pack, as I'm pretty sure that kit comes witrh a 26A controller. With 8C cells you'd only need 4ah to reach the max amps of the controller. So without knowing what cells you have it's an impossible question to answer.