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# Battery Wattage

Thu 5 Feb, 2015 09:39 am
What is difference, if any, between 2volts and 10amp battery or a 10 volt and a 2 amp battery?? Does the application influence it?
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Type: Question • Score: 3 • Views: 1,161 • Replies: 11
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dalehileman

1
Thu 5 Feb, 2015 11:29 am
@friday38,
Quote:
Does the application influence it?
Of course Fri, either one is capable of supplying a 20-watt load. But probably 99.9 times out of 100 apps, a more limited range of voltage is required, rarely over that 8-v range
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roger

1
Thu 5 Feb, 2015 11:32 am
@friday38,
It might help to know that the load draws Amps. The battery doesn't push Amps into the load.
dalehileman

0
Thu 5 Feb, 2015 11:40 am
@roger,
Fri, Rog's comment means that the lower the resistance (in ohms) of the load, the higher the current. Resistance is how easy the electrons can traverse it: I = E/R so with a 10-v battery, a resistance of 5 ohms will give you a current of 2 amps
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contrex

1
Thu 5 Feb, 2015 01:09 pm
@roger,
roger wrote:

It might help to know that the load draws Amps. The battery doesn't push Amps into the load.

You can say either that a load draws current from a source or that a source pushes current into a load. Both are true.

roger

1
Thu 5 Feb, 2015 01:15 pm
@contrex,
Oh. Okay, my 12 V car battery rated at 580 cold cranking watts is due to fry my turn signals. Good thing I never charged my phone from what used to be called the cigarette lighter port. Hate to see it after the battery pushed all them Amps into it.
contrex

1
Thu 5 Feb, 2015 01:37 pm
@roger,
roger wrote:

Oh. Okay, my 12 V car battery rated at 580 cold cranking watts is due to fry my turn signals. Good thing I never charged my phone from what used to be called the cigarette lighter port. Hate to see it after the battery pushed all them Amps into it.

The battery is able to "push" as much current into a turn signal as its resistance allows. The resistance of a turn signal lamp is much, much higher than the resistance of a starter motor. Thus the current is much much lower in the lamp than in the starter motor.

In fact, the current flows around a "circuit" from one of the battery terminals, through a switch, then to the load, through the load, and then back along another wire to the other terminal of the battery. The amount of current depends on two things: the voltage of the battery and the resistance of the load. Usually we say that the battery, which is a source of energy, "pushes" the current around the circuit.

See this explanation of a very basic electric circuit:

http://resources.schoolscience.co.uk/BritishEnergy/11-14/circh1pg1.html

contrex

1
Thu 5 Feb, 2015 01:44 pm
@friday38,
friday38 wrote:

What is difference, if any, between 2volts and 10amp battery or a 10 volt and a 2 amp battery?? Does the application influence it?

The difference is that:

You can get a current of 10 amps maximum at a voltage of only 2 volts out of the first battery. Thus if you had a 2 volt lamp that takes 1 amp, it would run for 10 hours before the battery went flat.

You can get a current of 2 amps maximum at a voltage of 10 volts out of the second battery. Thus if you had a 10 volt lamp that takes 1 amp, it would run for 2 hours before the battery went flat.

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InfraBlue

1
Thu 5 Feb, 2015 02:14 pm
@contrex,
Quote:
Usually we say that the battery, which is a source of energy, "pushes" the current around the circuit.

That "push" is by way of the negatively charged terminal, right?.
contrex

1
Thu 5 Feb, 2015 02:26 pm
@InfraBlue,
InfraBlue wrote:
That "push" is by way of the negatively charged terminal, right?.

The "conventional" direction of current flow in a DC circuit is from positive to negative, but it has been known for some time that the real direction is the other way. This convention was originated by Benjamin Franklin in 1752, and that at the end of the 1890s, with JJ Thomson's discovery of the electron, it became obvious that the actual flow of charge is from negative to positive. By that time the conventional flow idea had had 150 years of use. Both ideas coexist still.

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hsherm

-1
Thu 5 Feb, 2015 05:31 pm
@contrex,
I don't know where you heard that the current is "pushed", but it's referred to as "draws". The current is drawn out of the battery. However, that said, I think what really counts is that the original poster gets their answer.
contrex

2
Fri 6 Feb, 2015 02:05 am
@hsherm,
"Push" and "pull" are equally valid metaphors depending on whether you are considering generation or consumption of energy.
0 Replies

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