Maths question regarding cables

[gilby]

Sorry, my head hurts and formulae was never my strong point.

3 (maybe 3.5) metres from battery to batterys, (one, maybe two 125ah to two 110ah) what thickness cable would I need.

Also would the same thickness be needed for the neg to busbar with same length.

In addition to these questions, is there any truth that all charger leads to batteries should be of the same length?

Many thanks all.

[springy]

Taking your second question first - Yes the positive and negative cables should be the same size.

As far as the actual size goes - it depends on the load/charging current - you may have 350Ah plus of battery

capacity but if you only ever draw 2 Amps then quite skinny cable will do, on the other hand if your charger

is capable of putting 30-40 amps into the battery bank then much more substantial cable is required, and it

is probably this side of the system which will determine your needs.

 

springy

[Gibbo]

Basically the bigger the better. But diminishing returns past a certain size.

 

50mm is a good size for a balance of price/performance.

 

For your other query see............

 

http://www.smartgauge.co.uk/batt_con.html

[gilby]

Thank you and thank you.

Springy, it wasn't the neg' from batt to batt but the neg' to the actual domestic distrubution I was unsure of. The existing one is quite skinny and the new 'end' of the bank will require it an extra 1.2 metres of cable.