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7 votes

How is it possible that "fiddling around with" batteries can apparently give them more power?

It is common for both the button contacts on the ends of a battery and the springy metal fingers that make contact with those buttons to get a thin film of oxide forming on them. It does not take much ...
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3 votes

Why do I not get zapped when I hold my fingers on each end of an AA battery, like 3R12 ones?

with dry fingers, your skin represents a high resistance to the flow of electricity and so very little of it flows along your skin. In addition, there are no nerve endings right at the surface of the ...
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3 votes
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How much force needs to be applied on a battery cell to maintain contact?

Here are some examples from Lee Spring that could be useful. All the AA size springs listed have 1.75 lb nominal load. Source: https://www.leespring.com/battery-springs
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3 votes

Why do modern diesel electric submarines predominantly use lead acid batteries?

A) Specific energy isn’t so important for submarine batteries since ballast is needed Counter: This doesn’t account for space, which is vitally important, and lead acid batteries have relatively poor ...
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3 votes

Why do modern diesel electric submarines predominantly use lead acid batteries?

Lead-acid batteries are reliable, robust, easily recharged, and exhibit almost zero fire risk. Mass on a submarine is pretty much irrelevant.
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2 votes

How do mobile phones produce signals?

Your cell phone contains an oscillator. This is a circuit which when fed direct current converts it into ultrahigh frequency sine waves, which are then modulated by an encoded version of the audio ...
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2 votes

What do the different "mA" versions of this "battery eliminator" mean?

The current rating is the maximum current that the device will provide. If your device requires a higher current than the device will provide, it will likely overheat the power supply and may also ...
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  • 6,192
2 votes

Time period of charging a mobile phone via car

The "charger" or charge controller is in the phone. The external device is a power supply. On connection by USB the phone will negotiate with the charger to see how much power the charger ...
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  • 8,229
2 votes

Time period of charging a mobile phone via car

Not necessarily. The critical element between the power supply and the phone is the charger. Most phone chargers are at 5V and even the USB 3 they provide (at the time of writing) current of about 3 ...
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2 votes
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Modeling a simple capacitor

Capacitance only depends on its geometry, ... False. Capacitance is also determined by the dielectric (the insulator) between the plates and this can have a huge effect on the value obtained. ... ...
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  • 8,229
1 vote
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Can a battery-powered electric vehicle be driven through a dust storm?

I know of cars with the early electronic ignitions would misfire and cut out close to an army communications station. After some of the updates to the early electronic ignition systems they stopped ...
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1 vote

Time period of charging a mobile phone via car

No, it will be based on the output of the charger. Some do 1A others do 2.1A and some have 2 usb sockets. But be careful as some cars have the cigar lighter socket only live with the ignition on while ...
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  • 13.9k
1 vote

How is it possible that "fiddling around with" batteries can apparently give them more power?

In addition to @niels ' discussion of contact quality, for some battery types agitating the battery can cause the dielectric gel to rebalance its distribution (and quite possible pull resistant crud ...
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1 vote

Battery size and maximal power output

For any battery which works via electrochemical reactions, the voltage output of the battery will be the same regardless of its size as long as the chemistry is the same. However, the current output ...
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1 vote

lead acid battery discharge process

Negative plate reaction: $$ \mathrm{Pb}(s) \ + \ \mathrm{HSO_4}(aq)\ {\xrightarrow{\text{discharging}}}\ \mathrm{PbSO_4} (s) \ +\ \mathrm{H^+} (aq)\ +\ 2e^-$$ Positive plate reaction: $$ \mathrm{PbO_2}...
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