I was trying to explain the WHY to a buddy, I understand BIR & cable IR, cable length, etc. and understand that, but can't answer his question of why that is not also issues on batteries in series. What is it specifically about being in series that then resolves the problems the issues with parallel, cables, connections, etc. thanks
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I know you all say NO to parallel batteries, but
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Series and parallel circuit laws.
In series current is equal where I1 = I2 = I3 = I4
In parallel the current splits and are not equal.MSEE, PE 
Originally posted by littleharborcurrent will take the path of least resistance .
By that idiotic logic if you were to put a 1 ohm resistor in parallel with a 10 ohm resistor only the 1 ohm resistor would have current flowing which is pure rubbish. Assuming 1 volt is applied, you would have 1 amp flowing through the 1 ohm resistor, and .1 amp in the 10 ohm resistor for a total current of 1.1 amps.Last edited by Sunking; 04012018, 07:59 PM.MSEE, PEComment

Originally posted by Sunking View Post
That is pure Rubbish. Current takes all paths available.2.2kw Suntech mono, Classic 200, NEW Trace SW4024Comment

ok, clear as mud......so you made me go look up what "I" is which is current. so the current through each of the batteries in series by [U][B]must [/B][/U]be equal, but in parallel they could be different.
But physically why is that so? is there a flow of water analogy, like in parallel each battery is a reservoir that can have slightly different sized inlets and outlets that impacts how easily water can flow in or out of each reservoir on its way the end user, but in series what flows into the first battery must flow through each subsequent battery and out the end, thus no one battery can be less filled than the rest. I'm quessing this isn't right, but can you give a similiar sort of analogy?
And while cabling/connections can impact how freely current flows, thus different IR of cabling/connections can impinge the flow in either parallel or series, the negative consequences of such impingment in parallel connections is the different speeds of filling and emptying of each battery, and thus they can have different levels of "fill" or charge, whereas in series all the batteries must be at an equal level???
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Originally posted by Sunking View Post
That is pure Rubbish. Current takes all paths available.
By that idiotic logic if you were to put a 1 ohm resistor in parallel with a 10 ohm resistor only the 1 ohm resistor would have current flowing which is pure rubbish. Assuming 1 volt is applied, you would have 1 amp flowing through the 1 ohm resistor, and .1 amp in the 10 ohm resistor for a total current of 1.1 amps.Comment

Originally posted by dorff View Postok, clear as mud......so you made me go look up what "I" is which is current. so the current through each of the batteries in series by [U][B]must [/B][/U]be equal, but in parallel they could be different.
But physically why is that so? is there a flow of water analogy, like in parallel each battery is a reservoir that can have slightly different sized inlets and outlets that impacts how easily water can flow in or out of each reservoir on its way the end user, but in series what flows into the first battery must flow through each subsequent battery and out the end, thus no one battery can be less filled than the rest. I'm quessing this isn't right, but can you give a similiar sort of analogy?
And while cabling/connections can impact how freely current flows, thus different IR of cabling/connections can impinge the flow in either parallel or series, the negative consequences of such impingment in parallel connections is the different speeds of filling and emptying of each battery, and thus they can have different levels of "fill" or charge, whereas in series all the batteries must be at an equal level???
That is based on Ohm's law where E = I x R or (E= voltage, I = current, R = resistance). If E is the same in each "path" then lowering or raising the R value will change the I value in the opposite direction.Comment

MSEE, PEComment

Originally posted by Sunking View PostNow that is more correct.2.2kw Suntech mono, Classic 200, NEW Trace SW4024Comment

Originally posted by littleharbor View Post
Ya, my bad. Short answer, needed a little more info.
In theory if I take two 0.1 Ohm resistors, place then in parallel, apply 1 volt, each resistor will have 10 amps flowing. Ask any teacher or instructor and that is what they will tell you because that is all they know and never done it. In practice it does not work that way.
Now the question should be: WHY NOT?
Real simple, in real practice the resistors will not be equal. Now compound that with the fact cable resistance and contact resistance will not be equal. So now the teacher has to ask a tech, engineer, or sparky how to make it work? KISS (Keep It Simple Stupid) teacher, put the batteries in series.Last edited by Sunking; 04022018, 12:24 PM.MSEE, PEComment

Originally posted by dorff View Postok, clear as mud......so you made me go look up what "I" is which is current. so the current through each of the batteries in series by [U][B]must [/B][/U]be equal, but in parallel they could be different.
But physically why is that so?
is there a flow of water analogy, like in parallel each battery is a reservoir that can have slightly different sized inlets and outlets that impacts how easily water can flow in or out of each reservoir on its way the end user, but in series what flows into the first battery must flow through each subsequent battery and out the end, thus no one battery can be less filled than the rest. I'm quessing this isn't right, but can you give a similiar sort of analogy?
And while cabling/connections can impact how freely current flows, thus different IR of cabling/connections can impinge the flow in either parallel or series, the negative consequences of such impingment in parallel connections is the different speeds of filling and emptying of each battery, and thus they can have different levels of "fill" or charge, whereas in series all the batteries must be at an equal level?
If they are in parallel you can't force that to happen as easily, because most of the charge current will be going to the "better" cell strings that don't need to be balanced in the first place. The weaker strings will be neglected and will not get full balancing charges.
Note that this is unique to lead acid, which is why chemistries like LiFePO4 have very different requirements for balancing, monitoring and charging.Comment

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Originally posted by dorff View Postok, clear as mud......so you made me go look up what "I" is which is current. so the current through each of the batteries in series by [U][B]must [/B][/U]be equal, but in parallel they could be different. But physically why is that so?
Originally posted by dorff View PostBut physically why is that so? is there a flow of water analogy, like in parallel each battery is a reservoir that can have slightly different sized inlets and outlets that impacts how easily water can flow in or out of each reservoir on its way the end user, but in series what flows into the first battery must flow through each subsequent battery and out the end, thus no one battery can be less filled than the rest. I'm quessing this isn't right, but can you give a similiar sort of analogy?
Originally posted by dorff View PostAnd while cabling/connections can impact how freely current flows, thus different IR of cabling/connections can impinge the flow in either parallel or series, the negative consequences of such impingment in parallel connections is the different speeds of filling and emptying of each battery, and thus they can have different levels of "fill" or charge, whereas in series all the batteries must be at an equal level???
In a [B]series circuit[/B], the current through each of the components is the same, and the voltage across the [B]circuit[/B] is the sum of the voltages across each component. In a [B]parallel circuit[/B], the voltage across each of the components is the same, and the total current is the sum of the currents through each component.Last edited by Sunking; 04032018, 11:26 AM.MSEE, PEComment
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