Designing a 13s4p battery

B

BoomBoomShroom

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Nov 30, 2017
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Hi Guys,

I'm designing a 13s4p battery and this is my layout (Drawn on MS Paint... sorry in advance :p )


image_rqbcah.jpg


  • Blue is negative
  • Red is positive
Does this work? Also,Idon'tunderstand what gauge the bus bar has to be. I looked at a bunch of videos and checked around this forum, and no one seems to answer this question. Please send me a link if I'm wrong.

Also does 2A glass fuse wire work? Was looking at theseand they seemgood. I'm thinking about 2A because each cell is going to be outputting1A, and the charger I'll be using to charge the battery is going to be outputting54.6V 2A-3A.

All comments are appreciated. Trying to learn as much as possible,so I can slowly move up to a Powerwall.
 
Just a quick question. What are you trying to power? And what are the expected max current or wattage you want to get out of this pack?
 
jdeadman said:
Just a quick question. What are you trying to power? And what are the expected max current or wattage you want to get out of this pack?
Click to expand...

I'm building a ebike. Its a 48v 1000w kit. The max current is 26A (Haven't picked a kit yet, but the one I'm looking at has it at 26A).
 
BoomBoomShroom said:
Also,Idon'tunderstand what gauge the bus bar has to be. I looked at a bunch of videos and checked around this forum, and no one seems to answer this question. Please send me a link if I'm wrong.
Click to expand...

I think you haven't looked here: Frequently Asked Questions
as many of your above questions have been answered there.
 
Korishan said:
BoomBoomShroom said:
Also,Idon'tunderstand what gauge the bus bar has to be. I looked at a bunch of videos and checked around this forum, and no one seems to answer this question. Please send me a link if I'm wrong.
Click to expand...

I think you haven't looked here: Frequently Asked Questions
as many of your above questions have been answered there.
Click to expand...

Thatswhat i needed! Thanks.

So by my understanding its the current divided by the each cell in parrallel. Since i have a 13s4p and the current the controller is pulling in is 26A, I dontknow if its 26A/4 = 6.5A or 26A/52 (All the cells) = 500 mA.
 
Only cells connected directly in parallel
 
to add to Korishan I personally would not run a e-bike off recycled cells unless there was a low enough current per cell <500mA /cell

These cells are used and are more prone to failure when the demands are high. so for 26A load I would say you need minimum of 52 Cells in parallel. I have a lawnmower that I have 7s16p that it only draws 5A running.
 
52 cells in parallel?!? That is over 600 cells.

This is the kit i want. It actually says on the controller 22A give or take 1A.

Korishan - so its 26A/13 = 2A (or now 22A/13 = 1.7A)? I'm a bit lost on your wording there. Sorry I'm a visual learner... :-/
 
13s4p, so you have 4 cells in parallel. 26A / 4p = 6.5A per cell. So 2A glass fuses will not work here. And being used cells, they won't work either. Only if they are high drain cells and/or LiFePo4 cells would that be fine.

If you plan on 26A, you should have at least 30p, if not 50p or more to get <1A per cell. Most cells are rated at .2C (as mentioned in another thread), so that'd be close to 300mA for most cells. This will give you the best longevity
 
13s30p, that's 390 cells. At most I have 120 cells that are over 18000 mAh, and maybe I can get a few more. So at best i can hope for a 13s10p. At that point i reached 1 kWh battery.

Not looking good for my bike boys...
 
Sometimes math isn't kind but shows a harsh reality.

That's also one reason why ebike battery packs are packed in a tighter arrangement to get more cells


As an example:

image_wlvqff.jpg
 
The Other option is to get power cells, 10A or 20A rated cells but that comes at a price of capacity usually.
 
you can have my battery, :s have a look on my build thread i just posted today.
i made it from powertool cells, 10A discharge per cell. but even then... i dont know.
 
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