Yer average 12V car battery

Yer average 12V car battery

Author
Discussion

Simpo Two

Original Poster:

85,632 posts

266 months

Sunday 4th December 2016
quotequote all
I was watching Edd China take a battery out of a car on Wheeler Dealers, and wondered how much total energy is stored in one. For example, if all the energy was released in a fraction of a second, how much TNT would it be equivalent to?

My chemistry is far too inadequate to work it out but perhaps the thermodynamnic types here might have an idea!

Simpo Two

Original Poster:

85,632 posts

266 months

Sunday 4th December 2016
quotequote all
Half a kilo/one pound of TNT - not bad. Thanks Dave!

(Now back to my plans for a slow-release TNT battery...)

Simpo Two

Original Poster:

85,632 posts

266 months

Sunday 4th December 2016
quotequote all
Gandahar said:
What fraction of second? 1/10th, 1/1000th or 1/googolplex?

Is this science or bored arse scratching?
Well, we often hear that atom bombs are 'equivalent to X tons of TNT'. There's no timeframe attached to that. As for the rest, no, it's called curiosity, interest and liking to know.




And besides, if I use my car battery as a bomb I won't be able to drive home afterwards nuts

Simpo Two

Original Poster:

85,632 posts

266 months

Tuesday 6th December 2016
quotequote all
maffski said:
Wouldn't a 15kg car battery have the same energy as 15kg of TNT? (The OP did say total energy...) getmecoat
Ooh I like your thinking... and Pb is closer to U than the constituents of TNT!

Simpo Two

Original Poster:

85,632 posts

266 months

Wednesday 7th December 2016
quotequote all
AW111 said:
Simpo Two said:
Ooh I like your thinking... and Pb is closer to U than the constituents of TNT!
If Einstein is right, it should be exactly the same energy as it's weigh in TNT, or supermodels, or pizza. We just need an anti-battery to combine it with.

Would an anti-matter battery have the same polarity, or reverse?
I had lurched to fission not fusion. So if you're heading towards hydrogen, perhaps starting with heavier elements is a disadvantage...

As for the polarity, I'd guess it's reversed by definition...

Simpo Two

Original Poster:

85,632 posts

266 months

Wednesday 7th December 2016
quotequote all
Prof Prolapse said:
This thread is mental.

You want to know the potential electrical energy in a car battery expressed using the potential chemical energy in Trinitrotoluene in grams as units?

Then for some reason there's talk of time, presumably because someone is fudging their units.

Also typical batteries aren't explosive. The hydrogen gas can build up if a vent is blocked and this detonates. But it's not a closed system, so it's not correct to say the battery had the explosive potential to detonate a car bonnet, when actually it was caused a by product of the energy pumped in by the alternator not being able to escape.
It got interpreted in several ways. The original concept was that if a car battery has enough energy to turn a car engine over for, say, five minutes, what would that be like if it was all released in a fraction of a second? That introduced the issue of time - the faster you release a given amount of energy, the more explosive the effect. TNT is often used as a comparator because few people know what joules per kilonewton cubed or whatver means or feels like. We then moved onto e=mc2, which involves entirely different variables smile

Simpo Two

Original Poster:

85,632 posts

266 months

Friday 9th December 2016
quotequote all
More interesting is how you made a collage out of two headlights!