When using a power inverter, the runtime depends on the size of your battery, the power demand of the connected devices, and the battery’s reserve capacity. Below is a guide to help estimate how long you can operate various devices with different battery sizes.
12-Volt Battery Operating Time Chart
| Inverter Output Power | Load (Example Device) | BCI Group Size | 22NF (90 Min) | 24 (140 Min) | 27 (180 Min) | 8D (400 Min) | Dual 8D (900 Min) |
|---|---|---|---|---|---|---|---|
| 50 Watts | Stereo System | Operating Time | 9 HRS | 14 HRS | 20 HRS | 40 HRS | 80 HRS |
| 100 Watts | 27″ Color TV | Operating Time | 4 HRS | 6 HRS | 10 HRS | 20 HRS | 40 HRS |
| 200 Watts | Computer System | Operating Time | 2 HRS | 3 HRS | 4.5 HRS | 10 HRS | 20 HRS |
| 300 Watts | Blender | Operating Time | 1.3 HRS | 2.2 HRS | 3 HRS | 6 HRS | 12 HRS |
| 600 Watts | Small Coffee Machine | Operating Time | N.R. | N.R. | 1 HRS | 2.5 HRS | 6 HRS |
| 800 Watts | Small Microwave | Operating Time | N.R. | N.R. | N.R. | 1.5 HRS | 4 HRS |
| 1000 Watts | Toaster | Operating Time | N.R. | N.R. | N.R. | 1 HRS | 3 HRS |
| 1500 Watts | Full-Size Microwave | Operating Time | N.R. | N.R. | N.R. | 0.5 HRS | 2 HRS |
| 2500 Watts | Hair Dryer | Operating Time | N.R. | N.R. | N.R. | 0.2 HRS | 0.8 HRS |
N.R. = Not Recommended (the load is too high for the given battery size)
Tips for Maximizing Battery Life
- Deep Cycle Batteries: Deep cycle (marine) batteries are your best option for longer runtimes. They have high reserve ratings and are designed to handle repeated draining and recharging cycles.
- Battery Discharge Limits:
- Engine Start Batteries: Should not be discharged below 90% of their charged state. Doing so can significantly reduce their lifespan.
- Marine Deep Cycle Batteries: Should not be discharged below 50% of their charged state. Exceeding this limit can also shorten the battery’s life.
- Auxiliary Battery for Heavy Use:
- If you plan to run power tools or other devices that draw more than 200 watts for extended periods (over an hour), consider installing an auxiliary deep cycle battery. This auxiliary battery should be connected to the alternator through an isolator module. This setup prevents the inverter from discharging the engine’s start battery when the engine is off.
By following these guidelines, you can optimize your inverter setup for longer operation times and extend the life of your batteries.
