As my power source left somethings to be desired, I looked around for alternatives to my initial choice, the 9V block. My first intuition, fueled by YouTube Channels like Tom Stanton, who works a lot with them, was to use RC-Lithium Polymer Accumulators. They store great amounts of energy, they come in all shapes and sizes, I don’t need to throw them away after one use, so that’s an improvement.
But their biggest advantage also is a disadvantage. The energy density.
In normal batteries the chemistry involved is pretty stable, even at the event of an internal short circuit in the battery, it gets warm to the touch and maybe spills its insides. These may be corrosive and damage the batteries contacts and electronics they contact.
LiPos are different beasts.
They tend to combust, when experiencing internal shorts. This is due to the Lithium, which really wants some of that sweet oxygen in the air. Under normal conditions it is trapped in one of the electrodes, when current is withdrawn from the battery, the lithium ion moves from the anode to the cathode, passing an electrically insulating membrane. This membrane ages and may eventually fail.
In this event it is very important, how much charge is left in the battery. Is it down to just 10%? Good for you.
The more charge is left in the battery, the more current will flow through the failed membrane, heating the pack until it reaches temperatures high enough to catch fire.
Now you have a metal fire in your storage cabinet, you cannot put out with water.
The obvious solution is to store these cells with as little charge as possible in a thick walled metal box, each battery wrapped in a cushion of extinguishing agent.
Then you have to check their voltage in regular intervals, because you can destroy a LiPos chemistry by undervolting it.
You want a special kind of charger, that is able to balance the cells of a battery…
All in all, LiPos are a rabbit hole. They are great, but I don’t need that much performance and the risks involved
I wanted something a little easier to handle, store and use, so I took a look at Lithium-Ion Cells. Their energy density is a bit less than LiPos, but the metal casing makes them mechanically much more stable.
These LiIon cells are available in the sizes you know like 14500 which mechanically is an AA battery, but with 3.7V.
They still need a special charger, but this one does not need to balance individual cells against each other.