erin :Flag_Trans: on Nostr: it just occurred to me that putting 18650 cells into some devices feels like loading ...

it just occurred to me that putting 18650 cells into some devices feels like loading a 12-gauge shotgun. some designs even have a spring-loaded ejection mechanism.

not surprising - a “typical” 12-gauge shell is 18.5mm in diameter and at least 60mm in length. weight also roughly matches.

but how do they compare in terms of stored energy?

a “typical” 18650 is 250Wh/kg and weighs 45g or so. that’s approximately 40kJ per battery.

a “typical” 12-gauge shell may have as much as 38 grains of slow-burning smokeless powder. in normal units, that’s 2.45g or so. at an average modern smokeless powder energy density of 4300kJ/g, that’s 10.5kJ.

now, a shotgun shell is maybe 1/4 propellant by volume. rest is taken up by wadding and projectiles. meanwhile, a battery usually does not contain a projectile, it’s all battery.

which actually makes the two match perfectly in terms of effective energy density. an 18650 contains exactly as much energy as a pointless shotgun shell entirely packed with propellant would.

thank you for coming to my ted talk.