Yer average 12V car battery

Yer average 12V car battery

Author
Discussion

Simpo Two

Original Poster:

85,147 posts

264 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...

maffski

1,866 posts

158 months

Wednesday 7th December 2016
quotequote all
Simpo Two said:
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...
Nope, as Huff and AW111 say - E=MC^2 - annihilation rather the fusion (or fission).

Althrough we might be able able to get away without the anti-battery by dropping the battery in a black hole? Hawking Radiation should return the energy, and I wouldn't be surprised if that was faster than a TNT explosion. And then you'd just need a black hole under the bonnet, seems simple enough.

Prof Prolapse

16,160 posts

189 months

Wednesday 7th December 2016
quotequote all
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.

A car battery is lead and Sulphuric acid. Neither is explosive, so it's an odd comparison!










xRIEx

8,180 posts

147 months

Wednesday 7th December 2016
quotequote all
I don't think it's any weirder than measuring distance in terms of football pitches, double decker busses or smoots.

Simpo Two

Original Poster:

85,147 posts

264 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

Prof Prolapse

16,160 posts

189 months

Wednesday 7th December 2016
quotequote all
xRIEx said:
I don't think it's any weirder than measuring distance in terms of football pitches, double decker busses or smoots.
No, it's more like working out your daily calorie requirements, using the number of fun sized mars bars that can kill a miniature daschund with theobromine poisoning, as your units of measurement.

It's fking mental.




Prof Prolapse

16,160 posts

189 months

Wednesday 7th December 2016
quotequote all
Simpo Two said:
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
You'll have to forgive me but I'm a literal person, also a scientist of sorts.

-No battery car battery can turn an engine over for 5 minutes.

-The energy expressed would be exactly the same, the rate would differ, you can eat one mars bar every hour for a day, or 12 mars bars, energy is the same.

-The effect of the change in rate would be almost entirely dependent on the conditions, i.e. you can probably void all that stored chemical energy by simply neutralizing the acid in seconds. It may fizz, nothing more. High rates of energy change don't necessitate explosions of any description.

-TNT is used as a comparator for explosives. This isn't the case, so that's why I said it didn't make sense to me. It doesn't make anything easier.

-If we're discussing the energy released during nuclear processes then the original battery is totally irrelevant... Just work out the weights and the energy of the bonds.

xRIEx

8,180 posts

147 months

Wednesday 7th December 2016
quotequote all
Prof Prolapse said:
-No battery car battery can turn an engine over for 5 minutes.
I think Toyota, Lexus, Nissan, Renault, BMW and any other EV/hybrid manufacturer would disagree with you.

Sorry, I'm a literal person, I interpreted your post literally and had to point out why you are wrong; any fun sucked out of the conversation is purely coincidental.

Prof Prolapse

16,160 posts

189 months

Wednesday 7th December 2016
quotequote all
xRIEx said:
I think Toyota, Lexus, Nissan, Renault, BMW and any other EV/hybrid manufacturer would disagree with you.

Sorry, I'm a literal person, I interpreted your post literally and had to point out why you are wrong; any fun sucked out of the conversation is purely coincidental.
Would they? Only I'm pretty confident most (all?) manufacturers use a 12V "average" battery to power the starter and accessories. The Prius certainly has one. Even then it's a moot point as the OP said "average", which your alleged battery isn't.

It's a bloody science forum. You can't get upset for when someone pisses on your cornflakes for wanting to believe in magically exploding batteries.






xRIEx

8,180 posts

147 months

Wednesday 7th December 2016
quotequote all
Prof Prolapse said:
for wanting to believe in magically exploding batteries.
laugh

I apologise if you're Autistic, I don't believe in taking the piss in that situation, but you're taking taking things literally to another level.

Derek Smith

45,512 posts

247 months

Wednesday 7th December 2016
quotequote all
perdu said:
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
In the days of the PIRA there was a small explosion in a car in the City of London. Bomb squad did their normal (very brave) stuff and then in went a much more nervous fire brigade. I was told that there was a generator fault which overcharged the battery and hydrogen was given off. The battery was in a more or less sealed area then ignited (hydrogen and oxygen wants to be water I'm told). What ignited the hydrogen was not disclosed.

However, what surprised me was that it was hardly a unique occurrence according to the FB. I'd not heard of one before, nor heard it, and the same goes for since.


perdu

4,884 posts

198 months

Wednesday 7th December 2016
quotequote all
I get the impression from a quick reading that the someone is saying I'm wrong and that the battery couldn't/didn't blow up a car bonnet, maybe I'm missing something if so, sorry

But that incident DID happen

The energy released in the battery's demise did punch a hard corner section of said battery through the bonnet after punching through the padding which is a dense black fabric fibre type thing

And as Derek points out those exploding battery events are not unknown to the Fire Service

Very nasty way to start a shift

Pretty poor way to start your car too, the old guy was very badly shaken by it all

Derek Smith

45,512 posts

247 months

Thursday 8th December 2016
quotequote all
We were ordered to result a fire that the police were called to in the actual words of the senior or reporting Fire Service chap on scene.

There was a small explosion and a fire in a women's toilet.

The chap in the silver helmet said it was 'a momentary aberration of the sanitary towel incinerator'. I guessed that someone had told the FB of our recent force order. Again, as the chap said, fires in incinerators are hardly unusual.


Prof Prolapse

16,160 posts

189 months

Friday 9th December 2016
quotequote all
perdu said:
I get the impression from a quick reading that the someone is saying I'm wrong and that the battery couldn't/didn't blow up a car bonnet, maybe I'm missing something if so, sorry

But that incident DID happen

The energy released in the battery's demise did punch a hard corner section of said battery through the bonnet after punching through the padding which is a dense black fabric fibre type thing

And as Derek points out those exploding battery events are not unknown to the Fire Service

Very nasty way to start a shift

Pretty poor way to start your car too, the old guy was very badly shaken by it all
I was referring to you yes, I was just taking the piss however.

I don't dispute the battery "exploded", most likely hydrogen gas not vented. Batteries themselves aren't explosive however.

That's it.







Prof Prolapse

16,160 posts

189 months

Friday 9th December 2016
quotequote all
xRIEx said:
laugh

I apologise if you're Autistic, I don't believe in taking the piss in that situation, but you're taking taking things literally to another level.
I'm curious, how long did you spend Googling hybrid batteries, trying to prove me wrong before you came up with that gem?






Morningside

24,110 posts

228 months

Friday 9th December 2016
quotequote all
May years ago I remember in collage setting up two car headlights and then working out internal resistance, voltage and amps per hour plus total watts in joules (?) but cannot remember any of the calculations!

Piersman2

6,596 posts

198 months

Friday 9th December 2016
quotequote all
Morningside said:
May years ago I remember in collage setting up two car headlights and then working out internal resistance, voltage and amps per hour plus total watts in joules (?) but cannot remember any of the calculations!
Thankyou. A valuable contribution to the thread!

More so than this one admittedly, but not much more so! laugh

Morningside

24,110 posts

228 months

Friday 9th December 2016
quotequote all
Piersman2 said:
Morningside said:
May years ago I remember in collage setting up two car headlights and then working out internal resistance, voltage and amps per hour plus total watts in joules (?) but cannot remember any of the calculations!
Thankyou. A valuable contribution to the thread!

More so than this one admittedly, but not much more so! laugh
Well I just remembered sitting in the lab half asleep doing columns of numbers. Strange how your memory recalls things from the distant past that you totally forgot about.

Simpo Two

Original Poster:

85,147 posts

264 months

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

perdu

4,884 posts

198 months

Saturday 10th December 2016
quotequote all
Very very strong glue