Battery amps to kW
Enter the battery voltage, the current drawn and the battery capacity to get the power in kW and how long the battery lasts.
Inputs
Battery drain
How battery amps to kW calculator works
The battery amps to kW calculator converts battery current into kilowatts (kW) and runtime with 3 inputs: current, battery voltage and capacity in amp-hours (Ah). The calculator returns power, runtime, stored energy in kilowatt-hours (kWh) and the C-rate.
P = I × V / 1000 · t = Ah / I100 A from a 12 V, 200 Ah battery gives 1.2 kW for about 2 hours, a C-rate of 0.5C. The battery drawing drains at a speed set by the runtime.
Battery amps to kW formula
The battery amps to kW formula is P(kW) = I(A) × V(V) / 1,000. There are 3 battery formulas: power, runtime and stored energy.
Power
P(kW) = I × V / 1000100 A × 12 V / 1,000 = 1.2 kW
Runtime
t(h) = Ah / I200 Ah / 100 A = 2 h
Stored energy
E(kWh) = Ah × V / 1000200 Ah × 12 V / 1,000 = 2.4 kWh
Usable capacity depends on chemistry: lithium iron phosphate (LiFePO4) batteries allow 80–100% depth of discharge (DoD), and lead-acid batteries allow about 50%. Runtime at high current is lower than Ah ÷ A (Peukert effect in lead-acid).
Battery amps to kW conversion chart
The battery amps to kW conversion chart lists 8 currents from 5 A to 300 A with power at 12 V, 24 V and 48 V and the runtime of 100 Ah and 200 Ah batteries.
| Amps | 12 VkW | 24 VkW | 48 VkW | 100 Ahhours | 200 Ahhours |
|---|---|---|---|---|---|
| 5 A | 0.06 | 0.12 | 0.24 | 20 | 40 |
| 10 A | 0.12 | 0.24 | 0.48 | 10 | 20 |
| 20 A | 0.24 | 0.48 | 0.96 | 5 | 10 |
| 50 A | 0.6 | 1.2 | 2.4 | 2 | 4 |
| 100 A | 1.2 | 2.4 | 4.8 | 1 | 2 |
| 150 A | 1.8 | 3.6 | 7.2 | 0.67 | 1.33 |
| 200 A | 2.4 | 4.8 | 9.6 | 0.5 | 1 |
| 300 A | 3.6 | 7.2 | 14.4 | 0.33 | 0.67 |
A 1 kW inverter load draws 83.33 A from a 12 V battery and 20.83 A from a 48 V battery, so a 100 Ah battery lasts 1.2 h at 12 V and 4.8 h at 48 V.
Battery amps to kW Excel formula
The battery amps to kW Excel formula is =A2*B2/1000 with amps in A2 and battery volts in B2. Use =C2/A2 with capacity in C2 to get runtime in hours.
| A | B | C | D | E | |
|---|---|---|---|---|---|
| 1 | Amps | Volts | Ah | kW | Formula in D |
| 2 | 100 | 12 | 200 | 1.2 | =ROUND(A2*B2/1000,2) |
| 3 | 50 | 24 | 200 | 1.2 | =ROUND(A3*B3/1000,2) |
| 4 | 100 | 48 | 280 | 4.8 | =ROUND(A4*B4/1000,2) |
Add =C2/A2 in column E for runtime and =C2*B2/1000 in column F for stored kWh.
Battery amps to kW equation
The battery amps to kW equation is P = I × V / 1,000, and the runtime equation is t = Ah / I.
- P
- Battery power in kW
- I
- Battery current in amperes (A)
- V
- Battery voltage (V)
- t
- Runtime in hours (h)
- Ah
- Capacity in amp-hours
C-rate equals current ÷ capacity: 100 A from a 200 Ah battery is 0.5C, and 200 A from the same battery is 1C.
Battery amps to kW FAQ
How many kW is 100 amps at 12 V?
100 amps at 12 V is 1.2 kW (1,200 W).
How long will a 100 Ah battery run a 1 kW load?
A 100 Ah battery runs a 1 kW load for 1.2 hours (72 minutes) at 12 V: 1 kW draws 83.33 A. At 80% depth of discharge the runtime is 0.96 hours.
How many kWh is a 200 Ah 48 V battery?
A 200 Ah 48 V battery stores 9.6 kWh (34.6 MJ).
What C-rate is 100 amps from a 200 Ah battery?
100 amps from a 200 Ah battery is 0.5C. C-rate equals current divided by capacity.