battery cable size when adding a battery

[boatruptcy]

got the blue sea system add a battery kit with battery selector switch and vsr. i have 21' baja with single 454. the only house load is a std. cd player and nav lights, bilge etc. my total run from battery to switch back to starter would be about 9'. assuming the starter draws 300 amps at start up(i searched all over internet and there was never a hard and fast draw for a 454 so this is the number i saw the most) the wire size chart states that i will need 3/0 cable for this. it sure seems like a lot of wire for this application, i dont remember ever seeing any boats from factory or otherwise with 3/0 going to their battery switches. is this correct? could the starter not draw quite 300 amps? thanks in advance.

 

[bruceb58]

Re: battery cable size when adding a battery

Nine feet is a LONG way. Why so long? That is probably the reason you have never seen wire that large. I will double check the wire size we bought for my brother's 454.

Edit: I see that is total run. That doesn't seem that bad now. I know for my 454 it is not 3/0...might even be 0. If I remember correctly, my brother's is 1/0. I will check for you though. What size do you currently have? You can use that as a guide. You have fuel injection? Voltage drop is more critical if you do.

 

[boatruptcy]

Re: battery cable size when adding a battery

its currently a single battery mounted next to starter, it is obviously in engine room and there is no battery switch. I have a hatch actuator therefore i must mount the battery switch outside the engine bay underneath the rear seat, thus the longer than normal run. yes its mpi. the manufacturer has run two 2 gauge cables from battery to back seat and has stud connections for attaching a set of jumper cables. i of course have to use these every year to get the hatch open and charge or replace the battery. the weird thing is these 2 gauge cables go to the starter and the ground, rather than just the battery, dont know the point of that because if you cant get the hatch open from a dead battery that operates the actuator you sure dont want to be running the motor with a dead battery and no access. anyway, i guess that wire sizing is correct, can you verify that a starter actually draws 300 amps while cranking? at this point im prettty sure it does, and feel the 3/0 wire size probably is correct.

 

[bruceb58]

Re: battery cable size when adding a battery

This guy on Ebay has 4/0 and 2/0. You might even ask him for his recommendations.

http://stores.ebay.com/Genuinedealz__W0QQ_fsubZ156257019QQ_scZ1QQ_sopZ2

He can make the cables up for you. He does an excellent job.

 

[boatruptcy]

Re: battery cable size when adding a battery

thats funny, i just ordered a bunch of 4/0 from him, better to err on too big than too small. i have hammer crimp tool and everything i need to do it, i did notice though as i was getting everything prepped for it that all the house power feeds from the starter and goes through the wiring harness on motor. i downloaded the manual and am trying to figure out which run feeds small dist. panel in the cuddy, you have any experience with this? i really dont want to cut the factory harness but i need to isolate this panel or it is pointless to add a battery and vsr. thanks