Battery Capacity
C=xT
where C=capacity, x = amps, T = time
Power Consumption
Examples
Expresso Machine
| Power Consumption | 1400 w |
| Time | 10 min |
| Watt Hours | = 1400 x 10/60 = 233 wh / 0.85 (efficiency) = 275 wh |
Amp Hours P=IV I=P/V | = 275 wh / 12v = 23 Ah |
| How long will it run on a 80Ah battery? | = C / I = C / (P/V) = 80 Ah / (1400w / 12v ) = 0.68 hours = 40 mins |
Phillips Speaker
| Power Consumption | 10w |
Currnet ( I = P/V ) | =10w / 12v = 0.8A |
| How long will it run on a 80Ah battery? | = C / I = 80 Ah / 0.8A = 100 hours = 4.16 days |
How long using 4x 18650 2S2P (7.4v) C = 2 x 2Ah = 4Ah I = P / V I = 10w / 7.4v I = 1.35 A | = C / I = 4 Ah / 1.35 A = 3 hours |