WeVividWeVividFind how many hours your battery will run your load, and how big a battery you need for the backup you want.
Older batteries and heavy loads give less backup than this ideal figure.
Battery Ah × voltage × usable charge × inverter efficiency, divided by the load in watts.
Add the watts of everything you will run together, such as fans, lights, a TV and a router.
Old batteries, high loads and low temperatures all reduce it.
No. Everything is worked out in your browser and nothing you type is sent to a server.