Recommemded max run for 4 AWG used as battery cables

[JGator]

I'm interested in installing an additional battery on the Toon for running a bilge pump into a live well for caught fish when sitting idle without the motor running. I would rather the xtra battery not be mounted in the rear where the other battery is located due to the additional weight in the rear. I would also like this battery to be able to be used to start the motor in the event the main battery has failed for some reason. The distance from where I'd like to mount the battery to the switch would be between 10 to 12 feet. This would include the distance from the floor up to each terminal lug on the battery and switch. What is the max run 4 AWG should be? Of course larger cable is possible as I've not bought any.

Also can anyone point me to a vendor (iBoats by chance?) who would make custom length cable with crimped lugs? I've found 96" as the longest with lugs attached.

TIA

Jim

 

[Slide]

Re: Recommemded max run for 4 AWG used as battery cables

genuinedealz.com is the best place to get premade marine wire assembly. I just ordered 12 feet of 4/0 assembled battery leads for my remote battery setup.

 

[sam am I]

Re: Recommemded max run for 4 AWG used as battery cables

They(The "Experts") say a general rule of thumb is about a 0.5 volts max("on most vehicle starter/battery circuits.") for the voltage drop in starter wire(you stated you also want the batt. for possible starting purposes)


Assuming worst case is 24' total for both the positive and return wires max, 12' to the switch(+) and 12' to bus bar(-)



4 AWG (19/17) might be a tad small as seen in graph, at around 175AMP(throwing a dart!!.....typical draw from starter, mine anyway), it's about a 1.2 volt drop. However, this graph also shows you can do about 80 amps and stay around the 0.5 Volts range.




Here's a plot of 2 AWG (7/10) that gets it a tad better for ya if your starter is in the 175 Amp range.

Trying not to split hairs and get overly bogged down in details here so, just say'n............a general rule of thumb and given a known and some unknowns(your starter may need less? more? current etc)

Ya might want to look up the spec's on your starter and use the graphs from there......GL