I have a 20s14p made out of Panasonic ncr18650ga cells. rates it at 150A continuous and 200A burst for 5 seconds...to program my controller to pull 200A on hard start which should last about 2 to 3 seconds before the current drops ... max safe discharge current of a cell for the burst current?
Hi Sir, NCR18650 are great cells! They are Panasonic(made in China massive production) or Sanyo(made in Japan produced at Japan)
Those GA were developed by Sanyo at Japan & gone massive production by name brand Panasonic (China made, Japan development )
I've done at past some tests to add to my own cells database
Here results:
Discharge from 4,2V to 3,0V cut (done with icharger x12 and 18650 tester frame)
@3Adisch outputs 3182mAh final temperature 39 degrees Celsius
@ 5Adisch outputs 3187mAh final temperature 48,5 degrees Celsius
@ 7A disch outputs 3177mAh final temperature 57 degress Celsius
--> internal cell
IR average 29,4mOhms
-you get more discharge mAh if discharge down to 2,5V.. not recommend.. For high drain applications maybe good to cut at 3,3V or higher..(because temperature increase a lot at final curve from 3,3V to 2,5V)
dont pass 60 degrees Celsius at any cell (those were tests @ free air, so if U go @7A per cell discharge inside a closed enclosure could go more 10-20 degrees Celsius, this means 67-77 degrees Celsius final cell temp.. just sayin..)
Those GA are nice cells(red color and top blue circle), IR a bit high.. (see Sony VTC6 and Molicel maybe go around 10mOhms, thats why those handle up to 30-35A)
a 30mOhms cell is good for 10A, and a 10mOhm cell is good fro 30A discharge (maybe this is coincidence..)
anyway, if a cell is 10A rated for continues discharge, it should be able to handle 20A peak currents for few seconds (5seconds maybeOK.. example: a full acceleration at stooped veicule until reaches max speed cruise speed. Tesla takes 2-3seconds from 0 to100Km/h.. at this time is outputting full current from battery. I've tested a Tesla full acceleration at very high declive uphill and goes up to 900KWh (battery is 400V soo joule law means I=P/U= 1M/400V equals ~2500Amps) power demand!! almost a Million Watts & 2k5 Amps demand for 4seconds!!)
you go 14P battery, so do math 14Px20A equals 280A battery max peak draw for short time period. And continuous 140A
buttt 140A is a lot!! if U have a 20S battery 84V/avg 74V , means 74Vx140A = +10KW power out!!
Thats a lot continues power out, you never go on 10KW continuous!! and 20KW peak is massive for veicule (motor needs to be rated for 10KW/(20KW peak) to handle your 200A controller) (no one can drive full throttle all time @ 200A that is massive!!)
At your veicule, the only way to go 10KW continues is doin uphill at very high grade slope!!
Ure project is nice and OK for your 200A peak application.. Anyone correct me if I'm wrong!
but.. according GA datasheet, cell @ 10A disch and cut at 3,5V you only get 1000mAh!! & if You discharge 2A per cell, cut at 3,5V you get 2000mAh out!
If you have those cells GA at stock , just use those. If U are going to buy new cells, just choose lower IR cells (example SonyMurata Japan or Molicell and others)
U can build easy a
10P battery Sony and output up too
300A peak and keep high capacity!
Just analyse some cells datasheets, and have your own conclusions!
