Which of all known single-cell size types is equivalent to 3 AAA cells packed physically side by side to each other? My MacTronic Pro FL uses such holder.
in a triangle or flat?
triangle would be 18500 or if the carrier has a long snout 18650.
rolled up strip of cereal box as a spacer.
instantly reversible.
flat the closest li-ion would be a 103450. https://industrial.panasonic.com/ww...ondary-batteries/lithium-ion/models/NCA103450
thats what i put in things like harbor freight freebies,ect.
add a tp4056 to charge it.