[Pirape]

Hi, I have been wondering couple of question I cannot seem to find myself...

Depth of discharge for thundersky batteries are 70% DOD for 5000 charges

does it mean 70% of discharge or 70% not to be discharged?

eg: 40AH x 90s = 40AH x 288volts = 11520WH x 30% = 3456WH
or
eg: 40AH x 90s = 40AH x 288volts = 11520WH x 70% = 8064WH

Which formula is the one showing 70% dod?

 

[tomofreno]

It means 70% of the charge is discharged from an initially fully charged cell, so 30% remains. In this case the SoC, State of Charge, is 30%.

 

[Pirape]

Thanks it make sence now

so calculating the available WH I need to do

(VOLTS) x (AMP/HOUR) = (WATTS/HOUR) * (DOD)

288v x 60 = 17280 * 70% = 12096WH

from there I need to calculate the rage I will approximately get from it

(WATTS/HOUR) / (AVERAGE WATTSHOUR/MILE)

12096 / 250 = 48.384miles with 70%DOD

Where do I insert the Puerk effect?

 

[Duxuk]

The Peukert effect of lithium batteries is close to zero, so you can draw 70% of the energy in, say, one hour. Try this with lead acid and the Peukert effect means that you can rarely draw more than 50% of the total capacity. For repeated discharges you are only safe to draw about 25% of the total or you pack won't last very long.

Andrew.

 

[tomofreno]

Where do I insert the Puerk effect?

The way I did it was to calculate the discharge time accounting for the Peukert Effect. Then take the product of this and the vehicle speed to calculate the range. The Peukert exponent seems to be close to 1 for LiFePO4 cells, so the correction not really required. Though people on this forum did report somewhat lower range last winter with unheated cells.