What size battery cable?

32carv

32carv

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I need to add a house battery to my boat. My plan is to use the two current batteries which are identical as the house batteries and buy a new battery to be used as a starter battery. The house batteries will be wired in parallel. To create the house bank, I need to run about four feet of battery cable for each side. What size battery cable do I need?
Jim
 
What do you estimate the current draw to be? Once you know that there are tables to give you cable size.

George
 
Typically just the fridge and some interior lights while anchored out. No inverter. Don't know the exact amp draw.
Jim
 
The bigger the better heating your cables is simply put, wasting power. I'm using #2/0 on my Gulfstar upgrades for the house bank wire, the ProMariner inverter/ charger. I believe the boats original 4D combination start and house bank batteries have #1/0 wiring. I have about 30 feet of various lengths of #4/0 with lugs but I'll save that for if I ever install a bow thruster in this boat. I kinda doubt it at this point. She's got twin diesels and big rudders so I should be able to dock her in all but high winds single handed. I like bow thrusters but I can't see wasting the money if I don't need it.
Bill
 
What size batteries and will they be feeding a high current inverter/ charger? (I just read no is the correct answer) Will they be used for emergency cross over starting? If so I'd say #1/0 or #2/0. If not what size wire is coming off the alternators? Will the alternators be used to charge the house bank? It sounds like you can get away with either #4 or #2 if no emergency starting, bow thrusters or inverters are used.
Bill
 
We are missing a lot of information to give a good answer. Are your engines diesel or gas? What size batteries do you have now? If you have gas motors and car size batteries, can you put the bigger 8d batteries in their place. If they are gas and you cannot fit the 8d, I would reconsider one battery for both motors. I would get the extra battery and use it as the house battery. Starting batteries and house batteries are different anyway.

Billy K.
 
Gas engines. Don't want to do a lot of work or spend a lot on this. I have battery switch with 1/2/both/off. I plan to use the two current deep cell batteries which are one year old and identical and use them as a house bank. I will purchase one new battery and set it up as a starter battery. We only spend two or three nights per year on the hook so I don't want to add a forth battery. The current batteries are 800 starting amps and 114 amp hours. The battery that I purchase will be similar but newer so I will keep it separate as the starter battery while staying over night somewhere. The rest of the time I leave the switch on all.
Jim
 
Will the new house battery bank ever be used for engine starting? From the sound of the reserve amps they sound like 31 series batteries. If not used for starting the wire can be depending on the distance to the DC Main distribution panel be either #4 or #2 wire size the ground identical. If it's going to be used for emergency starting I'd suggest #1/0 or #1 again depending on the distance. That's a pretty wide range of wire sizes so the starting question needs to be answered. Even then the emergency starting part of the circuit and the battery combining cables need to be the larger sized wire and the feed from the battery switch to the DC panel could be as small as #4. I'm not seeing where you're using any heavy loads as a house bank.
Bill
 
I know you said you didn't want to put much work into this battery addition but you may want to think about the fact that 1/0 battery cable (which is what I would use in your application)isn't easy to work with. For marine use, you'll want to crimp on die-cast copper terminals. For that size wire, you'll need a fairly big crimping tool, too. You might be able to find 1/0 cable with the connectors in place, although I've never been able to find the right lengths.

Battery wiring is one area where you want to do it right.

Bill
 
32Carv I have a large 30" handled AMP battery cable crimp tool that will do from #4/0 to #6. If you tell me the positive and negative lengths needed and get me the marine grade wire, heat shrink & marine lugs I will make the cables up for free, you just pay shipping. I would suggest looking at Anchor marine wire and lugs.
They only take a few minutes to do. Otherwise you can probably find a local yard that could make them up for you.
Just an FYI the larger cable and lugs could cost as much as the battery your adding the proper cable is very expensive I don't recommend using welding cable only marine grade tinned wire.
Bill
 
Thanks for the offer Bill but I'm all set. Purchased #2 cable and installed New battery tonight.
Thanks,
Jim
 
quote:
Originally posted by 32carv

Thanks for the offer Bill but I'm all set. Purchased #2 cable and installed New battery tonight.
Thanks,
Jim

Click to expand...
As I mentioned #2 is more than enough as long as you are not trying to emergency start diesels. I'm glad it worked out for you.
Bill
 
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