Step 1: Multiply the power ratings of the appliances in watts by their usage duration in hours.
Step 2: This yields power consumption in watt-hours (Wh).
Step 3: Divide this value by the battery voltage (e.g., 12 V) to obtain power consumption in ampere-hours (Ah).
Here's a small calculator:
Usually found on the label on the bottom or back of the device.
minutes
Individual Consumer Consumption
Ah / Day
Total Consumption
Ah / Day
This is just a rough estimate of actual power consumption. Note that with most batteries except lithium, typically only about 60% of the specified capacity is usable.
