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Connecting battery to Circuit breaker
#1
Hello All
I am unsure which way should i connect the battery (14S*P 18650) to the circuit breaker. 
The two options is: 1st straight from the circuit break to the positve terminal and negative. pic 1
                            2nd From the circuit breaker to the middle and then to the postive and negative terminals pic 2.
Thanks
Andy
[attachment=1263]
[attachment=1262]
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#2
Cable lengths need to be the same.
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#3
Agreed. Doesn't matter where the cables run, just that they need to be the same length. This is also true for cables between packs. Each segment should be the same length.
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#4
I hope there is an output on that breaker! Otherwise it’s a short!
Crimp Daddy likes this post
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#5
Yep, I thought the same thing haha... most DC breakers I work with are generally single pole.
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#6
Can someone explain why the pos and neg cables should be the same length? Because I don't think it matters.

I understand that if you have batteries in parallel, that every pos cable should be the same length and every neg should be the same length in order to keep currents balanced. But that pos cables and neg cables need not be the same length.
Otherwise, putting a breaker on just the pos leg as many do would be a no-no? And virtually every device that uses a simple one pole power switch, typically with a much longer cable (think flashlights)? And cars which use the body as neg would be a major no-no, no?
mike likes this post
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#7
(03-10-2019, 01:57 AM)ajw22 Wrote: Can someone explain why the pos and neg cables should be the same length?  Because I don't think it matters.

I understand that if you have batteries in parallel, that every pos cable should be the same length and every neg should be the same length in order to keep currents balanced.  But that pos cables and neg cables need not be the same length.

I agree. Same length cables isn't necessary for this particular case and is just going to increase resistance since more cable is being used.
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#18650
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#8
Just wanted to add, like mike said: You want the runs to be as short as possible to reduce resistance. And only as long as necessary, taking into consideration things like safety (eg. avoid heat sources, or where people might trip over), electrical noise sources, and the all important aesthetics ;-)
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#9
Resistance isnt the reason why inverter battery cables need to be the same length, and run parallel, bound together where possible.

Inductance is ..... 

Inductance, and the associated ripple in DC inverter battery cables reduce efficiency and will lead to the premature demise of your inverters input stage.

It's long been best practise to keep all aspects of battery to battery, and battery to inverter cabling as symmetrical as possible.

In a system using cascaded, or inverters in parallel, identical battery cable length is vital.

Those cheap high output inverters, that folks seem to favour on here, really dont like DC ripple.
Crimp Daddy likes this post
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#10
To add, generally speaking when connecting a charger to a battery, it needs to have equal length cables. Normally the construction of the system has the pack separated by a breaker. So the charger/inverter/loads are separated by the breaker. Which usually means that the cables from the "breaker" to the pack should have the cables the same length.

As far as the resistance, if the wiring is properly matched with the voltage, then resistance isn't an issue at all.
Proceed with caution. Knowledge is Power! Literally! Cool 
Knowledge is Power; Absolute Knowledge is Absolutely Shocking!
Certified 18650 Cell Reclamation Technician

Please come join in general chit-chat and randomness at Discord Chat (channels: general, 3d-printing, linux&coding, 18650, humor, ...)
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