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### Topic: What's this called when 2 Power Sources... (Read 2422 times)previous topic - next topic

#### cjdelphi

##### Sep 25, 2013, 04:08 pm
2 power sources are connected together... for simplicity sake.

2 12v lead acid batteries, - to + and + to - where the wires meet where do the electrons flow? a simulator just says a short but what actually goes on here? the energy is way more intense than just a direct short.. so what's going on here?

#### alnath

#1
##### Sep 25, 2013, 04:22 pm

it is a short : you wire two 12V batteries in serie , and you short the + and the -  ,
you've just short a 24V battery

don't touch the wire that makes the short, it will burn your hand very quickly (yes, I tried once : a piece of metal shortened the battery of my car, before I could take it off, it became red, then white, and my hand was on it !! )

#### cjdelphi

#2
##### Sep 25, 2013, 04:37 pm
yeah, but a straight short, from - to + is bad.

I once connected a 1amp 19v charger backwards (without a diode or anything to protect it) back  to front and that wire that connected to the alligator clip simply vanished in a poof of smoke!

(i was half asleep at the time, wide awake shortly after the small explosive charge)

#### MarkT

#3
##### Sep 25, 2013, 04:52 pm

2 power sources are connected together... for simplicity sake.

2 12v lead acid batteries, - to + and + to - where the wires meet where do the electrons flow? a simulator just says a short but what actually goes on here? the energy is way more intense than just a direct short.. so what's going on here?

If both batteries are in good nick this is just like shorting both of them out, the current's the same, the
voltage is all dropped across internal resistance and cable resistance dumping ~10 kW into both.

However if you don't fully short them out there is twice the voltage available to hold a DC spark, which
will then be ~4 times as powerful as one battery (but this is just a DC load, not a true short ciircuit!)

High power DC arcs are pretty stable (arc welding), especially at higher voltages, and the size depends on the
available power more than anything.  The length of the arc can be longer with higher voltages, but
high power also helps.
[ I will NOT respond to personal messages, I WILL delete them, use the forum please ]

#### mmcp42

#4
##### Sep 26, 2013, 08:29 am
do you mean simply two batteries in parallel?
should be ok if they're both the same type and at the same charge state
will simply double the capacity
there are only 10 types of people
them that understands binary
and them that doesn't

#### cjdelphi

#5
##### Sep 26, 2013, 09:24 am
no, imagine jump starting a car, but instead you cross the leads.

Say bye to the jumper cable lol... maybe even a splash of acid lol, no I was trying to work out if it's just 2 12v shorts or 24vs of short and where the electrons were traveling since there's 2 grounds.

either way don't do it unless you like burnt fingers...

on another note, getting a lithium 3v watch battery too hot makes it go bang, but it had a nice fragrance when it did....

#### Shpaget

#6
##### Sep 26, 2013, 09:36 pm
It is shorting.
Batteries are made from multiple cells, when you connect on + to one -, you are connecting another battery in series or in other words, just adding more cells to the system. When you connect remaining + and -, you are doing the same thing as a short with one battery, only with twice as much available energy.

#### Henry_Best

#7
##### Sep 27, 2013, 05:15 am

no, imagine jump starting a car, but instead you cross the leads.

Say bye to the jumper cable lol... maybe even a splash of acid lol, no I was trying to work out if it's just 2 12v shorts or 24vs of short and where the electrons were traveling since there's 2 grounds.
The electrons are going round in circles. I hear that they get dizzy
There's no difference between two 12V batteries connected in series and one 24V battery, so there's not 2 grounds. By shorting them/it out, you could say that there's no ground at all, as the -ve terminal is connected to the +ve terminal.
Quote
either way don't do it unless you like burnt fingers...

#### SirNickity

#8
##### Sep 27, 2013, 05:39 am
I call it assault on batteries.  g'heh..

#### Henry_Best

#9
##### Sep 28, 2013, 03:43 am

I call it assault on batteries.  g'heh..

I'm positive that you should be on a charge for that comment.

#### mmcp42

#10
##### Sep 29, 2013, 04:39 am

no, imagine jump starting a car, but instead you cross the leads.

Say bye to the jumper cable lol... maybe even a splash of acid lol, no I was trying to work out if it's just 2 12v shorts or 24vs of short and where the electrons were traveling since there's 2 grounds.

either way don't do it unless you like burnt fingers...

on another note, getting a lithium 3v watch battery too hot makes it go bang, but it had a nice fragrance when it did....

ooh lots of molten jumper leads, sparks, sore hands
generally not recommended!

but as others have said it's like simply connecting a very low resistance across a low impedance 24 volt source
so v high current until something gives up

alternatively first think of the setup as two 12 volt batteries in series ( = 24 volts)
the -ve of one is ground
the +ve of t'other is 24 volts
the middle ( +ve of 1st, -ve of second) is "just" a centre tap

now put your zero-ohm load (the other wire) from +24v and gnd
stand well back!
there are only 10 types of people
them that understands binary
and them that doesn't

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