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# AAA actually powering a TV?

Registered User regular
edited November 2007
So after watching that stupid video (I'm not even going to link to it, in case somebody other then Lord Thanda starts to think the video is real) with the guy "powering" his TV with a AAA battery, I began to wonder what would it take to actually power my 27in TV downstairs with a AAA battery?

I've done some prelim calculations and this is what I've figured out so far:

First, My TV runs off of 120V AC power (standard for the US) and the AAA battery I've got says 1.5V DC. So there has to be a power inverter in the mix. And since there has to be a power inverter in the mix, I'm going to have to run 8 AAA batteries in series to get the 12 volts required to run the power inverter. Looking on the back of the TV, it says 119 Watts which, using Joule's Law, means that it's current is right around 1 Amp. And according to Duracell's site, the AAA alkaline battery is rated for a use of 1.25 amp-Hours.

So does that mean that I could run my 27 in TV for over an hour off of 8 AAA batteries runing through an inverter? Has anybody done anything like this? Am I missing something using the knowledge I remember from my introduction to electrical engineering class I took back in high school over 5 years ago?

Qs23 on

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Not actually a mod. Roaming the streets, waving his gun around.Moderator, ClubPA Mod Emeritus
edited November 2007
My knowledge of electrical engineering is dim, but don't circuits operate on principles analogous to mechanics?

For example, you can take a motor and pump up its torque by a factor of ten. However, the power output of the motor is constant, so you have to drop the speed by the same factor of ten to do so, because you can't magically make the motor better than it is.

My instinct is that if you upped the voltage by a factor of 80, you'd drop the life by a factor of 80, and be able to run it for about a minute. Or else it would kneecap some other feature of the battery, making it unusable.

Someone more proficient in this shit can probably answer the question better.

ElJeffe on
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83 Blue Ridge Protects the Holy Registered User regular
edited November 2007
What ElJeffe said. I think the step you may have missed out is the drain the inverter has on the batteries when it's producing your 120V/1A AC output.

For a transformer to produce 120V from 12V, it has to step the voltage up ten times. Not at all coincidentally, it has to step the current down ten times too. Thus to get 120V @ 1A your inverter (essentially a fancy transformer) is drawing 10A from your battery of 1.5V cells.

So that would be a total of 0.125 hours then. Or 7.5 minutes, assuming that the inverter is 100% efficient. Not the best use of a bunch of AAA's I can think of, but still a respectable amount of time under the circumstances.

Mr_Rose on
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Registered User regular
edited November 2007
I haven't seen the video, but by bypassing the internal AC->DC converter, you just need to convert one voltage to whatever the TV uses. That way you don't get the DC->AC->DC power loss. That's likely to be significant at that level of power.

evilmrhenry on
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Not actually a mod. Roaming the streets, waving his gun around.Moderator, ClubPA Mod Emeritus
edited November 2007
Efficient or not, I would love to see someone pull it off. Better yet, try to rig an entire home theater set-up to run off a AAA battery for a period of, like, 5 seconds.

ElJeffe on
I submitted an entry to Lego Ideas, and if 10,000 people support me, it'll be turned into an actual Lego set!If you'd like to see and support my submission, follow this link.
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Registered User regular
edited November 2007
Well ya know, I would love to crack open a TV and see what DC voltage it will need... granted I really don't want to do that with my tv downstairs... to craigslist batman!

Qs23 on
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Registered User regular
edited November 2007
Mr_Rose wrote: »
What ElJeffe said. I think the step you may have missed out is the drain the inverter has on the batteries when it's producing your 120V/1A AC output.

For a transformer to produce 120V from 12V, it has to step the voltage up ten times. Not at all coincidentally, it has to step the current down ten times too. Thus to get 120V @ 1A your inverter (essentially a fancy transformer) is drawing 10A from your battery of 1.5V cells.

So that would be a total of 0.125 hours then. Or 7.5 minutes, assuming that the inverter is 100% efficient. Not the best use of a bunch of AAA's I can think of, but still a respectable amount of time under the circumstances.

Also there is no way any AAA cell you can get at any retail store will put out 10A... you would need more than just 8 AAA's in parallel (maybe 64 in 8 sets of 8 in parallel/series, hehe).

midgetspy on
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Registered User regular
edited November 2007
Qs23 wrote: »
Well ya know, I would love to crack open a TV and see what DC voltage it will need... granted I really don't want to do that with my tv downstairs... to craigslist batman!
In case someone starts playing McGyver: do remember that in old (crt) tv:s there can be enough amps stored to kill you long after its turned off, so don't open up a tv to "fiddle" around.

Jelloblimp on
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Registered User regular
edited November 2007
Jelloblimp wrote: »
Qs23 wrote: »
Well ya know, I would love to crack open a TV and see what DC voltage it will need... granted I really don't want to do that with my tv downstairs... to craigslist batman!
In case someone starts playing McGyver: do remember that in old (crt) tv:s there can be enough amps stored to kill you long after its turned off, so don't open up a tv to "fiddle" around.

well of course. Being in a family with a couple of electrical engineers, I'm not going to do anything without their supervision.

Side note: My dad wired a key switch onto the back of the TV to allow him to lock off the power to the tv in-case he thought we were watching too much tv. Well my brothers and I, while he was out of the house, wired up a secondary switch around his key switch to bypass it... and that was when none of us were even out of high school yet.

Qs23 on
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Registered User regular
edited November 2007
Jelloblimp wrote: »
Qs23 wrote: »
Well ya know, I would love to crack open a TV and see what DC voltage it will need... granted I really don't want to do that with my tv downstairs... to craigslist batman!
In case someone starts playing McGyver: do remember that in old (crt) tv:s there can be enough amps stored to kill you long after its turned off, so don't open up a tv to "fiddle" around.

Man, this one time I shocked myself like a motherfucker from an old 19" CRT monitor. Luckily only went through and out one hand, rather than thru the old ticker (else I'd be posting this from beyond the grave, rather than Southampton)

ben0207 on
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Registered User new member
midgetspy wrote: »
Mr_Rose wrote: »

Also there is no way any AAA cell you can get at any retail store will put out 10A... you would need more than just 8 AAA's in parallel (maybe 64 in 8 sets of 8 in parallel/series, hehe).

Actually most batteries other than dry cells can handle a discharge rate of C10, ie a current in amps ten times their amp hour rating, so AAA cells rated at 1.25ah should be able to handle 12.5 amps. However you'll get less than the rated amp hours. Also, I'd strongly recommend shielding the battery pack in a strong box in case the batteries explode, and possibly using a heat sink to stop the batteries getting too hot. Make sure the batteries still have room in the box to explode, otherwise the box could explode with even more force.

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Registered User new member
OOPS, the quote didn't get included in my post. Here it is (if it works this time :-) )
midgetspy wrote: »

Also there is no way any AAA cell you can get at any retail store will put out 10A... you would need more than just 8 AAA's in parallel (maybe 64 in 8 sets of 8 in parallel/series, hehe).

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A dagger in the dark is worth a thousand swords in the morningRegistered User regular
ben0207 wrote: »
Jelloblimp wrote: »
Qs23 wrote: »
Well ya know, I would love to crack open a TV and see what DC voltage it will need... granted I really don't want to do that with my tv downstairs... to craigslist batman!
In case someone starts playing McGyver: do remember that in old (crt) tv:s there can be enough amps stored to kill you long after its turned off, so don't open up a tv to "fiddle" around.

Man, this one time I shocked myself like a motherfucker from an old 19" CRT monitor. Luckily only went through and out one hand, rather than thru the old ticker (else I'd be posting this from beyond the grave, rather than Southampton)

Can you honestly say you're currently better off?

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Institutionalized Safe in jail.Registered User regular
ben0207 wrote: »
Jelloblimp wrote: »
Qs23 wrote: »
Well ya know, I would love to crack open a TV and see what DC voltage it will need... granted I really don't want to do that with my tv downstairs... to craigslist batman!
In case someone starts playing McGyver: do remember that in old (crt) tv:s there can be enough amps stored to kill you long after its turned off, so don't open up a tv to "fiddle" around.

Man, this one time I shocked myself like a motherfucker from an old 19" CRT monitor. Luckily only went through and out one hand, rather than thru the old ticker (else I'd be posting this from beyond the grave, rather than Southampton)

Can you honestly say you're currently better off?

what you did there. I see it.

GT: Acidboogie PSNid: AcidLacedPenguiN
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A dagger in the dark is worth a thousand swords in the morningRegistered User regular
Also I was trying to rip on Southampton...

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Institutionalized Safe in jail.Registered User regular
resistance to your punnery is futile?

GT: Acidboogie PSNid: AcidLacedPenguiN
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A dagger in the dark is worth a thousand swords in the morningRegistered User regular
Something something my pun was so bad it turned Volta into a buddhist... (Ohmmmmmmmm... ohmmmmmmmm...)