Every home should have a simple multimeter to measure electrical current in batteries and wall outlets. You can purchase a simple multimeter from places like Harbor Freight for under $10. Multimeters have many uses but the I use them mostly to read voltage in wires and wall outlets and testing batteries.
If you want to know if wires or an outlet have live power you can set the meter to AC, touch the probes to the contacts, and read the voltage. This is very useful when making repairs and testing circuits. In an emergency the integrity of your house could be compromised and you may need to test the circuits.
A multimeter is very useful for testing batteries. Set the meter to DC, touch the contacts to the battery poles, and read the voltage. Properly discard old batteries. I keep the good batteries in one box and low batteries in another. I use the low batteries in remotes (these need very little power) and when the remote stops working I discard the batteries.