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What happens if 12V bat is connect in parallel wif a 5V bat?

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Richard48

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Would someone pls help me?
I always hv this query that what if a 12V battery is connect to a 5V battery?
What will be the resulting voltage? Thanks!
 

Its going to be lower than 5V
 

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    Richard48

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Re: What happens if 12V bat is connect in parallel wif a 5V

Thks cydi. I just tried with 2 power supplies. One set to 5V and the other to 12V.

I short the both -ve terminals together. When I short both the +ve terminal, the resulting voltage is 12V. Its seems that the lower voltage will follow the higher voltage. Hmm.....I don't know the reason.
 

Hi

It pretty depends on the characteristics of the battery or power supply you are using.

In theory, If you are using 2 batteries, the result should be 12V if the power is infinite, this is because the lower voltage battery has an internal resistance, and behaves as a load rather than a power supply when connected to a higher voltage battery. You can find the numerial explanation studying the Thevenin equivalent circuit, for example here https://www.allaboutcircuits.com/vol_1/chpt_10/9.html

if you think this information was useful click on "helped me" for statistics

Sal
 

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    Richard48

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Re: What happens if 12V bat is connect in parallel wif a 5V

It's very simple really.

The 12v supply will not only drive the load but also CHARGE the 5v supply !

Back when we used to put batteries in parallel to get more power, they used to blow up all the time till our TA told us what we were doing !!
 

Re: What happens if 12V bat is connect in parallel wif a 5V

when you connect two ideal voltage sources of 12V and 5V in parallel then assuming the internal resistance to be 'r' & taking r -> 0 & by solving by Thevenin's theorem we have the voltage coming out to be (12+5)/2=7.5V and the internal resistance is r/2 which is 0.
 

Re: What happens if 12V bat is connect in parallel wif a 5V

If the internal resistance is small enough, so maybe an explosion occurs.
 

Re: What happens if 12V bat is connect in parallel wif a 5V

If u mean Ur connecting the same polarities then the resulting voltage would be

somewhere between 5 & 12 depending on their internal resistances.

By the way. Ive never seen regular batteries explode! I mean they just heat up a little bit.

regards!
 

Re: What happens if 12V bat is connect in parallel wif a 5V

The thing is that power supplies are not batteries i.e. they have diodes in them so

the internal diod of the 5-volt-power supply is reverse biased when connected to

a 12-volt-power supply hence rising the voltage up to 12 volts...

Hope this get u off the hook.
 

Re: What happens if 12V bat is connect in parallel wif a 5V

Q:
batteries with different potential in parallel
Click to expand...
A:
Its not so much that doing so isn't allowed - its just that no good comes from doing so when the potentials don't match.

For equations:
1) try picking a wire size and length, or a trace size and length - calculate resistance therefrom
2) Using internal battery resitances and the conductor resistance, calculate current flow and the temperature rise per unit time - compare to heat dissapation rate
3) impress the interviewer with your ability to gage not only the time required for the copper to melt, but the ammount of light (if any) produced
4) further impress the interviewer by calculating battery temperatures after the wire pops - also calculate amp-hours remaining in each battery
Click to expand...

My people skills end when questions like this begin.
Click to expand...

Regards,
IanP
 

Re: What happens if 12V bat is connect in parallel wif a 5V

1. the potential difference between two nodes will be same for all braches connected across .
2.any source should be considered as pure source in combination with source resistance.
3.current will flow from high potential to low potential

knowing those parameter , u can find the potential diff acoss the batteries by apllying kirchoff's laws.
 

Re: What happens if 12V bat is connect in parallel wif a 5V

narccizzo said:
Current = (12V-5V)/(internal R of 12v + internal R of 5v)
Click to expand...

This is what will confuse u. Plz refer to my earlier post if u dont want to get mixed up.
 

Re: What happens if 12V bat is connect in parallel wif a 5V

Ok, you are right, this only works for BATTERIES. :)[/quote]
 

Donot connect the two batteries in parallel.cell are never used in parallel.u can damage ur battery.
 

Re: What happens if 12V bat is connect in parallel wif a 5V

When you connect 5V in parallel with the 12V battery, you are going to make Kirchoff very angry!!! In practice, there is some resistance between the batteries and a very large current equal to 7V/resistance will flow. Please don't try this at home!!! If the sources that you are using are current limited, then the systems will protect themselves from sourcing/sinking too much current.

best regards,
v_c
 

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