3270 battery ground cables

[fxvielander]

When I bought my 1986 3270 a few years ago it came with three black heavy gauge battery ground cables. Two of them are attached one each to the negative terminals of my two group 27 12-volt batteries. I have a third however that is not attached to anything. The other end of all three cables route along the base of the port fuel tank to a point forward of the port engine to then presumably attach to a grounding point somewhere I cant readily see. When consulting the owners manual wiring schematic, it shows three battery ground cables with the third servicing a generator starting battery -- this I do not have; while I do have a relatively recent vintage generator, it uses the same starter battery as the diesels. Does anyone else have this same configuration? If yes, am I correct in assuming this third battery cable continues to not need to be attached to anything, as it would just be redundant to the existing grounding cables I have already attached to my negative battery terminals?

[O1dSoldier]

I have a 1990 3288 that I picked up about 3 years ago. It came with a negative lead from the house battery to the starboard engine, a negative lead from start battery to port engine, and the negative lead connecting both engines.

[CapMartin]

I have a 1990 3288 that I picked up about 3 years ago. It came with a negative lead from the house battery to the starboard engine, a negative lead from start battery to port engine, and the negative lead connecting both engines.

+1

[green650]

Sounds like you might be missing a battery. Unless, you only have one start battery and one house battery?
I believe my engine start battery had 2 grounds going to it, one going directly to each engine block. The house batteries had one ground going to the port engine. And then from there a beefy ground wire ran to the transom where I had a terminal connect all my grounds.

[MonteVista]

Sounds like you might be missing a battery. Unless, you only have one start battery and one house battery?
I believe my engine start battery had 2 grounds going to it, one going directly to each engine block. The house batteries had one ground going to the port engine. And then from there a beefy ground wire ran to the transom where I had a terminal connect all my grounds.

I think that is the right way of doing it. There should also be a separate grounding cable that joins the two engines together to eliminate a single point of grounding failure.

[fxvielander]

So to clarify, yes I have two batteries, one start battery and one house battery. So the key question seems to be do others with 3270s (or 32XXs) have two grounding cables connected to the negative post of the start battery, and one grounding cable connected to the negative post of the house battery, as Green650 describes in his post above (assuming owners have what I believe to be is the stock two battery arrangement provided by Bayliner)? If yes, I'll connect my second grounding cable, which is currently not connected to anything, back up to the negative terminal post of my start battery!

[O1dSoldier]

Myself and CapMartin both have a single neg from house and start bats and one connecting both engines. The other two didn't say.

[fxvielander]

Ah, thanks for the clarification -- so you and CapMartin have an arrangement where there is a third cable not passing to the batteries but rather just connecting both engines together, right? For me I have three cables terminating at or near my two batteries, one going to each battery and the third not connected to anything but clearly in the vicinity of the battery bank (so that end should connect to a battery of some kind, I believe).

Sounds like I'm closest to what green650 describes, where again I should take that third ground cable and connect it to my start batt (so two to the start batt and one to the house batt). Can anyone else confirm if they have that arrangement? Sorry if I'm being dense here or overthinking this but don't want to start connecting that third ground to something and make matters worse -- my boat seems to be working so want to be mindful of old "if it aint broke don't fix it" rule...!

[O1dSoldier]

I don't see any benefit of having two neg. cables connected to a single battery. It seems to me connecting the two engines together would be the better option and would add a better layer of redundancy to the overall grounding system rather than just the start battery. For example, if somehow the neg. from the house battery comes loose your starboard engine is not grounded where if the two engines are connected together, if either battery looses it's neg. cable for whatever reason both your engines will remain grounded.