Samsung 20R vs 25R

[mchlpeel]

I'm looking to buy a battery from em3ev and have 2 choices

The packs are 50.4v nominal and I want to draw 60amps max from them


Pack 1
Samsung 25R 22.1Ah

Pack 2
Samsung 20R 17.5Ah

Would the packs deliver 60 amps with no detrimental effects or is one better than the other.

 

[r3volved]

From a quick googling - looks like they're both close to 10C. The 25R does 25a continuous discharge and the 20R does 20a.

...I see the 20R range between 20-22a and the 25R range between 20-25a depending on the site.

 

[spinningmagnets]

Either pack will easily supply 60A peaks.

 

[Simple818]

No problem doing 60a. Will barely sag. Probably sag like 2 volts

 

[markz]

From a quick googling - looks like they're both close to 10C. The 25R does 25a continuous discharge and the 20R does 20a.

...I see the 20R range between 20-22a and the 25R range between 20-25a depending on the site.

You are saying that one battery cell of 25r can crank out 20-25A?
So a 4P pack will spit out 80-100A at whatever voltage your Series string is at. With more P you decrease the voltage sag.

 

[mchlpeel]

From what I gather

25r = 8c

20r = 10c

So take your pack Ah and times it by the c rate above to find max continuous current

 

[neptronix]

No problem doing 60a. Will barely sag. Probably sag like 2 volts

Per the spec sheet ( attached ):

A 20AH 25R pack at 4C ( 80A ) will drop from 3.61v nominal to 3.44v nominal.

That's a 0.17v drop per cell.
At 4C and 14 cells in series, you will see 14 x 0.17v = 2.38v drop when you hit it with a 60A load.
Yeah, you're just about right on the money there for a 3C load.

8C performance is bad and the cells become 3.27v nominal, as low as lifepo4.
0.34v x 14 = 4.76v of sag across your ~50v 20ah pack. Your cells also go from 30C to 95C.
Yeah, don't do that.