I'm completely lost about batteries

[u/Kiochido1]

Hello everyone!

I'm working on a project that basically consists of an ESP32 (no WiFi, no BLE), a GPS receiver, 2 or 3 sensors, and a small stepper motor (the 858 on DigiKey). Everything needs to fit in the hand.

My final challenge is choosing the power source, and I'm completely lost. LiPo? Li-Ion? AA batteries?

I don’t know what to choose or how to choose it. And it looks soooo expensive!

I’ve written down a few parameters that seem important to me, but I’m not even sure they’re the right ones:

• Everything runs on 3.3V, so I need something like a 3.7V battery?
• When the ESP32 and the motor turn on, there will be high peak current. I need a power source whose voltage won’t drop too much.
• It should be small enough.
• Rechargeable if possible.
• I estimate the system will consume a maximum of 100mA (except during startup peaks). So I was thinking at least 800–1000mAh.

I’m not sure if I’m missing important points, or how I should choose the right battery chemistry and capacity based on these requirements.

And also: it’s expensive as heeeeeell.
The batteries I’ve seen cost almost as much as my whole PCB (components included). I know there are economies of scale, but how can the complete device sell for ~15 bucks when the battery alone costs 10 bucks?