what will be the total voltage of more than two voltage sources connected in parallel to each other?

Answer 1

Unless the voltages are exactly the same (in which case the output voltage will be that voltage) the greater voltage will start shoving current through the lesser voltage supply.
This lesser voltage supply will then be loading the greater voltage supply.
The internal resistance of the greater voltage supply will have a voltage drop across it so the output voltage will be less than the unloaded greater voltage supply.
For switching power supplies the voltage can be so "stiff" that it acts as a virtual ground and you have something approaching a short circuit.
This is the reason why you do not hook ni-cad batteries in parallel as they have a very small internal resistance.
Edit:
In response to dmb06851
I may have used the term loosely but my explanation was already getting way too technical for what he had asked.
When the stronger supply starts pushing a current into the weaker supply the output stage of the weaker supply, which is usually trying to pull the voltage down to a specific point, will send feedback to its previous stages saying that it has too much voltage. The control circuit will try to lower the voltage which the stronger supply senses so it tries to send more current. This fighting tends to look like it will end up as a short circuit, but not a real short circuit. The circuits will either reach an equilibrium or not.
http://en.wikipedia.org/wiki/Virtual_ground
I am not a switching supply expert as some of it does look like voodoo to me too.
An ideal voltage supply has zero internal resistance and a switching supply tries to be ideal.
This means that any voltage difference at all (even microscopic ones) must be dropped across the conducters. This is a short circuit.
Second edit:
I was using "ground" as synonomous with zero reference voltage.

Answer 2

In terms of idealised circuit components this is equivalent to divide by zero. The nodes either side of the batteries are at 20V and 15V at the same time, which is impossible. Real batteries are modelled by an ideal voltage source plus a series resistance (called the internal resistance). Thus when two battery models are connected together the voltage drop between the ideal sources is shared across the two internal resistances as a potential divider. In general it is a bad idea to connect any batteries in parallel except for ones that are nominally identical.

Answer 3

You can not connect two voltage sources of different voltages. If both voltages are equal you can connect them in parellel. The total voltage remaains the same giving mor3e current rating.

Answer 4

I wonder if JC would be good enough to explain what he means by " it acts as a virtual ground and you have something approaching a short circuit."

In particular what he means when he says "virtual ground" and what "gound", virtual or otherwise, has to do with it?

He might learn something from reading this http://www.davidbridgen.com/earth.htm


It's good of JC to respond.

Yes, I do know about voltage sources.

I still question the use of the totally irrelevant "ground".

Answer 5

connected in parallel, they add more power, not more voltage

the voltage only adds in series