Yer average 12V car battery
Discussion
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!
My chemistry is far too inadequate to work it out but perhaps the thermodynamnic types here might have an idea!
Simpo Two said:
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!
What fraction of second? 1/10th, 1/1000th or 1/googolplex?My chemistry is far too inadequate to work it out but perhaps the thermodynamnic types here might have an idea!
Is this science or bored arse scratching?
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.Is this science or bored arse scratching?
And besides, if I use my car battery as a bomb I won't be able to drive home afterwards
Simpo Two said:
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
That sounds even more dodgy And besides, if I use my car battery as a bomb I won't be able to drive home afterwards
Is true though
A car I attended back in the days of being an AA man had its battery explode when the owner tried to start it one mild spring day
The explosion blew the top corner of the battery through the bonnet
The bonnet was on a newish Ford Granada and had a couple of inches thick sound deadener hung below the bonnet itself
When I got there it looked at first as if someone had parked a pig's ear on top of the bonnet
It wasn't until I got close I could see it was about three inches of the moulded corner piece, top and two sides that had punched a triangular hole and almost escaped
and the insides of the engine compartment were completely covered in battery acid, little pieces of the plates and the white plastic framework of the grids that hold the innards in place
I closed the bonnet and sent for a local garage to play with it next
No fun for the poor owner, he was still shattered from the noise of the explosion
A car I attended back in the days of being an AA man had its battery explode when the owner tried to start it one mild spring day
The explosion blew the top corner of the battery through the bonnet
The bonnet was on a newish Ford Granada and had a couple of inches thick sound deadener hung below the bonnet itself
When I got there it looked at first as if someone had parked a pig's ear on top of the bonnet
It wasn't until I got close I could see it was about three inches of the moulded corner piece, top and two sides that had punched a triangular hole and almost escaped
and the insides of the engine compartment were completely covered in battery acid, little pieces of the plates and the white plastic framework of the grids that hold the innards in place
I closed the bonnet and sent for a local garage to play with it next
No fun for the poor owner, he was still shattered from the noise of the explosion
Gandahar said:
What fraction of second? 1/10th, 1/1000th or 1/googolplex?
Is this science or bored arse scratching?
No, it's a legit question.Is this science or bored arse scratching?
To rephrase it for pedantry :
How many joules are "stored" in a typical car battery ("stored" because it's actually a chemical reaction, not a capacitor).
How many joules/gram are released from the detonation of TNT?
Time is not a factor in either case (it would be different if the question involved power).
I did a similar calculation when we had a catastrophic failure of some rotating equipment at work, to highlight the destructive potential.
However, most battery explosions are due to ignition of hydrogen disassociated from the water-based electrolyte due to over-charging.
xRIEx said:
ianrb said:
davepoth said:
12 volts, and about 50 amp-hours means 0.6 kWh. One tonne of TNT makes about 1.2 MWh, so an average car battery has as much energy as 500g of TNT, more or less.
May want to check your units there.
Skyrat said:
xRIEx said:
ianrb said:
davepoth said:
12 volts, and about 50 amp-hours means 0.6 kWh. One tonne of TNT makes about 1.2 MWh, so an average car battery has as much energy as 500g of TNT, more or less.
May want to check your units there.ianrb said:
Skyrat said:
xRIEx said:
ianrb said:
davepoth said:
12 volts, and about 50 amp-hours means 0.6 kWh. One tonne of TNT makes about 1.2 MWh, so an average car battery has as much energy as 500g of TNT, more or less.
May want to check your units there.Skyrat, point taken on the capitalisations.
maffski said:
Wouldn't a 15kg car battery have the same energy as 15kg of TNT? (The OP did say total energy...) 
No, nothing like, unless you could burn the entrie mass in a fusion reaction, E=MC^2 etc.The battery in my daily is 12v, 95Ah nominal. It weighs 23.5Kg (according to Halfords). At a terminal voltage of 12.8v that's about 1.2Kwh, or 43MJ absolute max.; more likely is c.85% of that deliverable.
- or only about the energy content of 1.2 litres, or 0.9Kg, of petrol...
maffski said:
Wouldn't a 15kg car battery have the same energy as 15kg of TNT? (The OP did say total energy...)
paulrockliffe said:
Would it? The different elements would have different ratios of neturons, protons and electrons, so I suspect it wouldn't.
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?
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