Neg battery cable

[VBtravisD]

So I know there are a million threads about wiring a dual battery switch. I searched a bunch for info before I decided to post my question. Just a quick background. I am in the process of rigging a small 16' skiff. I purchased a perko dual battery switch, have 2 deep cycles (which are not the same group size!), my outboard has remote start and steering and I plan on running a 12v trolling motor and a handful of low draw accessories.

My game plan is to have everything hooked up to the common. I figure I can select one battery or the other to operate all the accessories on the boat. And in an emergency situation I can elect to run off both batteries. I realize that in order to be able to start the motor off both batteries the outboard must be grounded to both. I have seen where guys run a jumper from 1 neg to the other neg. But then I read that this is improper unless you bump up the gauge of the cable to the outboard. Is this true? I have seen where people run a dedicated neg from each battery to the outboard. But what about the accessories? I need to make sure that they are all grounded to both batteries too. So do I run a cable from each battery to a bus bar? Finally, would I have any issues running on the "all" setting with 2 different sized batteries?

I figure I want to do this correct, the first time. Any info would be greatly appreciated!

 

[bruceb58]

Re: Neg battery cable

You can easily get away with running a negative cable from one battery to the other and not bump up the cable to the engine as long as it starts fine now and you haven't increased the length.

I would only use the both setting when the engine is running when you want both batteries to charge or in the case where you need to have both batteries connected together in an emergency starting situation where both are too low to start on their own.

What sized outboard are we talking about here? It is probably small enough that the amount of charge current that its going to be putting out is pretty small so you are going to probably be charging your batteries when you get home with an onboard charger rather than relying on the outboard charging them.

 

[VBtravisD]

Re: Neg battery cable

Whoops sorry... a 1993 Johnson 60 hp. I try to keep my starting battery on a trickle charger almost all the time. I used to keep 1 strictly for my trolling motor and the other ran my nav lights, fish finder and my starting battery. But now I figure it will be easier to just hook the 2 up to one switch and control things.

 

[glenn property of pam]

Re: Neg battery cable

the wire between the 2 batterys has to be equal or larger than the wire to the motor starter. the negative for the boat acc connects to either battery negative as they are now joined. keep your switch on the starting battery and leave your trolling motor on the trolling battery then use the switch if you ever get a problem firstly by trying to start of the trolling battery then if that doesnt work wait a few mins then try the dual. if its wont start then say a few nasty words and tell the boat what you plan to do with it and use the pull rope to start the motor (this is normally when you realise that you pulled the kill switch cord accidently and thats why it wont start)