Powering Nano without blowing off my head?

I'm making a Madeye moody eyeball using a nano and a continuous servo. I need to power it via batteries, but I'm not familiar at all with lithium batteries or battery boosters. I DO know how to use AA batteries and a voltage regulator but 4 AA batteries strapped to my head is pretty bulky.

Trying to figure out exactly what I'd need to get a lithium battery on then figure out how to charge it is turning out to be quite daunting, I really just want a 3.7 lithium charger-booster combination thing, but I can't find anything like that.

Any ideas?

Thanks!

If you are going to put this on your head I would strongly recommend not building it yourself, and buying something from a reputable source.

Google “electronic cigarette explosion” or “rc battery explosions” and you will understand why...

Franck

Why not just use a small USB power bank? Would that be small enough?

DrAzzy:
Why not just use a small USB power bank? Would that be small enough?

This is what I originally thought but it seems like all of them that I can find on amazon have an automatic shutoff switch. If the charger doesn't have enough current being drawn from it, it shuts off. Since the servo won't always be running, I'm thinking the little bit the nano draws just to process won't be enough (or at least that's what people are speculating online).

heropants:
This is what I originally thought but it seems like all of them that I can find on amazon have an automatic shutoff switch. If the charger doesn't have enough current being drawn from it, it shuts off. Since the servo won't always be running, I'm thinking the little bit the nano draws just to process won't be enough (or at least that's what people are speculating online).

https://www.dorkbotpdx.org/blog/paul/battery_pack_load

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franck102:
If you are going to put this on your head I would strongly recommend not building it yourself, and buying something from a reputable source.

Google “electronic cigarette explosion” or “rc battery explosions” and you will understand why...

Franck

Yikes... And with that, I'm thinking I might just run a the wires from the eye, around the strap and down to my back where I can use 4 AA batteries and a voltage regulator circuit.