Calculating battery capacity

[gofastman]

Hi folks, first post here! This isn't necessarily related to the DNA200, but when calculating Watt/hour capacity for the power supply, do you use the batterie's nominal voltage (3.7) or its maximum voltage (4.2)? Thanks!

[VapingBad]

The nominal battery voltage.

[gofastman]

Thanks! I assume nominal mAh capacity is used also?

[VapingBad]

Wh = mAh x nominal_voltage / 1000

11.1 V (3 cells in series)
2000 mAh (per cell)
=
11.1 x 2000 /1000 =  22.2 Wh

or

3.7 V (single cell)
6000 mAh (3 x 2000 mAh cells)
=
3.7 x 6000 / 1000 = 22.2 Wh


So series and parallel come out the same Wh.

[gofastman]

I'm using 3 25Rs, nominal capacity is 2500mAh. Capacity in high drain conditions is significantly less. Should I calculate it as 2500, or try to figure out mAh capacity under the conditions they will be used with this device?

[VapingBad]

In series so 11.1 V x 2500 mAh, but 3.7 V x 3 x 2500 mAh gives the same answer of 27.75 Wh.

(IIRC the specs on 25Rs have nominal A 3.6 V, which would give 27 Wh)

[gofastman]

Oh yeah, duh, far less current draw on each cell (vs. a single cell mech) because of the higher voltage.