if all (-)s are on stud, connecter ground stud to stud or post to post??

MMDAVIS

Recruit
Joined
Jul 9, 2011
Messages
3
Hi there,

I'm attempting to hook up dual batteries and using a perko switch, I was told to run (+) on batt 1 to #1 post on perko and (+) on batt 2 to # 2 post on switch, all wires currently hooked on (+) on stock battery to the common post on perko, I also got told to run (+) from alternator to common post on perko..so far is this correct?? That all sounds ok to me, the question I have is about the grounds, I know I need to hook the (-)s of batt 1 to batt 2 together, but if all the (-)s are connected to the studs on the batt does the connector ground have to be (-) stud to (-) stud, or can I connect the (-)s on the batteries from (-) post to (-) post, as I have both (-)posts and (-) stud on both of the batteries?? Also the next question about the grounds is.. Does it matter which battery the grounds are connected to or is it once the (-)s on the batteries are connected to eachother, it all becomes essentially one big ground connection and won't matter what wire goes to what (-) they are all 1?? If soome people on here can set me straight and confirm that the way I am wiring it is correct that would be greatly appreciated!! Thanks in advance!
 

Silvertip

Supreme Mariner
Joined
Sep 22, 2003
Messages
28,758
Re: if all (-)s are on stud, connecter ground stud to stud or post to post??

Ground is ground (negative terminal on the batteries). Both negative terminals must be connected together. Then another cable needs to run to the engine block so it has a ground path. After that it doesn't matter which ground you use because -- ground is ground. The best bet however, is to hook ground wires directly to the negative terminal on either battery.
 

sdowney717

Petty Officer 2nd Class
Joined
Jul 16, 2011
Messages
155
Re: if all (-)s are on stud, connecter ground stud to stud or post to post??

hopefully your post to stud or post for all the negatives is a big wire. On my boat it is 2/0
bigger wire is always better with low voltage DC.
Some people have or make a copper grounding bar. Run cable from batt neg to bar and then all negative grounds hook up on that.

I have a positive copper bus bar which takes the positive output from the selector switch to bar and I have starters, etc... hooked up there.
My negative only has the inverter negative to the negative battery post and engine ground wires from the blocks. The negative returns from the boat are bolted to the engine block heads on the starboard motor.

What I might change is adding a high amp fuse on the positive that feeds the boat and inverter wires, but not fuse the starters.

battery studs should likely be nuts not wing nuts. Unless you tighten them up with pliers.
 

MMDAVIS

Recruit
Joined
Jul 9, 2011
Messages
3
Re: if all (-)s are on stud, connecter ground stud to stud or post to post??

Ok so negative is negative, it doesn't matter which negative which wire is hooked to just as long as its negative. Makes sense. Yes my wires are big they are 4 gauge. As for the rest of my wiring that I explained in intail post , does it all sound like that's the way to hook it up?? Or should I hook it a different way?? Thanks again guys
 

MMDAVIS

Recruit
Joined
Jul 9, 2011
Messages
3
Re: if all (-)s are on stud, connecter ground stud to stud or post to post??

So I now have it all wired up and everything seems to have power when the switch is turned to proper settings, but since I am doin this install in my driveway, I can't really run the boat to see if the alternator is charging the batts? I didn't run a new wire from alternator to batteries or the common switch, don't know if I need to? There is wires coming off of the alternator to a fuse on the starter then a wire from starter to common on switch (these wires were that way stock, except went to batt not perko from stock, as I added perko) so I am wanting to know if that will work to charge batteries or if I should run a separate cable from alternator to something?? Also I have all of the negatives hooked to 1 batt and the 2 negative post of the 2 batts connected but what I am wondering now is if the battery with all the negatives hooked up to it dies, when I go to switch to other battery to start will it still be able to start being hooked to the dead battery? Will it still get a ground or do I need to move all engine related (-)s to the starter battery?? If someone could get back to me asap as I am in the process of wiring this right now that would be great! Thanks in advance!
 
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