Start batteries repositioning

[saaristo]

In order to better balance the boat I'm planning to reposition two start batteries. What would be the best route to go? Myself I was thinking to mount a pair of insulated 100 amp capable bus bars to where the batteries currently are and run four awg 4 cables (2 pos + 2 neg) from these bus bars to the new location of the batteries about 10 ft in lenght. On the picture batteries under question are top left corner and new location would be down right corner (not fully visible). Not sure about the awg's, busbar amps etc however. Any suggestions?

 

[Bondo]

Ayuh,..... That sounds like alota potential corrosion points,.....

I'd mount the batteries where ever you want, then buy longer bigger cables to run back to their current connection points,...

 

[Scott Danforth]

10 foot run and you are not going to use 4 gauge the motor will never spin over. maybe 0000

your current cables are bigger than 4 gauge. they look like 2 or 0

and skip the buss bar idea like Bondo noted way too many connections. simply remove your short cables and install fatter and longer cables.

 

[saaristo]

Thank you guys for input. Inve crawled in the boat some more and found a marking on the existing neg cable, turns out it is already awg 2/0. So my idea of awg 4 is completely off. Awg 2/0 at the same time seems also an overkill. So maybe yes, just dump the existing cables and run whole length new cables from new location to bat switches and engine, using the same awg 2/0.

Just some sidenote, interesting that my european made diesel SUV has a battery pack in the trunk and it runs awg 4 some 17 ft or so cables to front. I would imagine spinning a diesel is way harder than gas.

 

[froggy1150]

Your diesel probably has a high torque or gear reduction starter.

 

[Scott Danforth]

Thank you guys for input. Inve crawled in the boat some more and found a marking on the existing neg cable, turns out it is already awg 2/0. So my idea of awg 4 is completely off. Awg 2/0 at the same time seems also an overkill. So maybe yes, just dump the existing cables and run whole length new cables from new location to bat switches and engine, using the same awg 2/0.

Just some sidenote, interesting that my european made diesel SUV has a battery pack in the trunk and it runs awg 4 some 17 ft or so cables to front. I would imagine spinning a diesel is way harder than gas.

coming from a background where I used to design diesel and natural gas engine installations, you will most likely need 4/0 (0000) cable. on some larger diesel engines, with a 20 foot run between the batteries and starters, we were running 500MCM cable

its all about what the starter pulls and what the cranking voltage is with the motor cranking above its minimum RPM

some diesels only need to spin over 100 RPM and they will fire. your MPI engine needs to spin close to 300 RPM for the engine to fire