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18650: Quick Math

ttatlanta

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The more energy we store in a battery, the more devastation it could cause when broken or damaged. But how much energy do we store in our 18650s, exactly?…

Let's take a 2,750 mAh battery for its face value: 2,750 mAh and 3.7V.

2.75 Ah * 3.7V = 10.175 Wh.

1 Wh is 3600 Joules, so we have 10.175 Wh * 3600 = 36,630 Joules of energy stored in a single battery.

Let's take gasoline for a comparison, assuming that we have an "average" gas with 33,400 Wh / gallon energy density, or 120,240,000 J / gal.

36,630/120,240,000 = 0.0003046407186 gal, or 1.15ml of gas.

:tldr:: 18650 cell stores about the same amount of energy as 1.15 ml of gasoline.
 

MrScaryZ

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what? comparing gasoline and 18650 batteries make sense
 

Train

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o_O
So...if my battery's runnin' low while I'm cutting the grass, I can just pour a little gas in there to keep it running 'til I'm done!
Sweeet!
Do I pour it on the battery, or drip it into my atty?
Does it have to be unleaded?
:eek::eek::eek:
 

ttatlanta

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what? comparing gasoline and 18650 batteries make sense
Would you rather have a TNT equivalent? K, that'll be 4,184 J/g, so in our example 18650 will have the same amount of energy that is stored in 8.76 grams of TNT.

Now, if we take a Tesla Model S with its 1,776 18650 cells and inflict some damage to that

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conanthewarrior

Gold Contributor
Member For 4 Years
I think the TNT equivalent makes more sense actually lol.

A bomb releases energy, as does a battery. One just does it all at once, while another does it slowly at our chosen rate. At least we hope it happens slowly ;)
 

Mikhail Naumov

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The gas conversion didn't really strike me too much, also different circuits have different efficiency ratings, as do gasoline engines. So it's a slippery slope and it only kind of works on paper, but still, as an EE I completely understand the random desire to make conversions like this for fun. Basing it off the raw source of output energy (the battery or gasoline) does work fine, though.
 

ttatlanta

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…as an EE I completely understand the random desire to make conversions like this for fun. Basing it off the raw source of output energy (the battery or gasoline) does work fine, though.
Actually, I was thinking more along the lines of "If 18650 experiences a catastrophic failure in a non-nukelar environment, it cannot release more energy than it stored, which is an equivalent of…" :idea:
 
The more energy we store in a battery, the more devastation it could cause when broken or damaged. But how much energy do we store in our 18650s, exactly?…

Let's take a 2,750 mAh battery for its face value: 2,750 mAh and 3.7V.

2.75 Ah * 3.7V = 10.175 Wh.

1 Wh is 3600 Joules, so we have 10.175 Wh * 3600 = 36,630 Joules of energy stored in a single battery.

Let's take gasoline for a comparison, assuming that we have an "average" gas with 33,400 Wh / gallon energy density, or 120,240,000 J / gal.

36,630/120,240,000 = 0.0003046407186 gal, or 1.15ml of gas.

:tldr:: 18650 cell stores about the same amount of energy as 1.15 ml of gasoline.
Seems make sense, but gotta consider about batt as a wrapped explosive once explodes which I think will cause more devastation in comparison with gas.Perhaps due to I never saw a gas bomb exploding, cannot imagine that. But a batt., whooop! Kinda scary!
 

PoppaVic

Gold Contributor
Member For 4 Years
further ahead comparing it to N cc of Smokeless powder (name one with an apropos burn rate), or black powder, (4F I suppose).
 

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