How to determine how much battery you need has been gone over MANY times before, but since the word still hasn't gotten around, here goes...
Determine the worst case current requirement in amperes (A). Just worry about the current since everything will--presumably--take 5v. In your case, that will be the Pi3B (2.5A) plus whatever the display requires.
Multiply the current by 5v to get power requirement in watts (W).
Multiply the power in watts by the desired run time in hours to get watt-hours (Wh).
Add about 20% to the watt-hour requirement to allow for inefficiencies in things like voltage conversion. This is now the Wh requirement of your battery.
If you are going to use a commercial powerbank, be aware that the "Ampere-hour" (usually expressed as "milli-ampere-hours for marketing purposes), is at the nominal cell voltage of 3.7v. So to get the watt-hour capacity of a powerbank, multiply the ampere-hour by 3.7v.
Note that you are probably going to find that you need a significantly larger battery that you are expecting.
Any beginning course in BASIC ELECTRICITY should enable you to do these calculations on your own.
Determine the worst case current requirement in amperes (A). Just worry about the current since everything will--presumably--take 5v. In your case, that will be the Pi3B (2.5A) plus whatever the display requires.
Multiply the current by 5v to get power requirement in watts (W).
Multiply the power in watts by the desired run time in hours to get watt-hours (Wh).
Add about 20% to the watt-hour requirement to allow for inefficiencies in things like voltage conversion. This is now the Wh requirement of your battery.
If you are going to use a commercial powerbank, be aware that the "Ampere-hour" (usually expressed as "milli-ampere-hours for marketing purposes), is at the nominal cell voltage of 3.7v. So to get the watt-hour capacity of a powerbank, multiply the ampere-hour by 3.7v.
Note that you are probably going to find that you need a significantly larger battery that you are expecting.
Any beginning course in BASIC ELECTRICITY should enable you to do these calculations on your own.
Statistics: Posted by W. H. Heydt — Sun Oct 19, 2025 11:51 pm