Battery Disconnect on Ground???

[StormRider01]

1988 Bayliner Capri 2152, previous owner had replaced original engine cover with bench seating, and installed a battery disconnect on the ground side?

Is there _ANY_ good reason for this?

 

[seabob4]

Re: Battery Disconnect on Ground???

A battery switch (this is what I assume you mean by a battery disconnect) can be installed on the hot or the ground side of a circuit, It is simply an on/off switch which interrupts current flow. In a 12V system, this will work on the path coming out of the batt (positive side) or the path going back to the batt (negative side).

Unusual? Yes. Anything wrong with it? No.

 

[shankbri]

Re: Battery Disconnect on Ground???

I don't think it matters much - but the correct place is as yours is - on the negitive terminal.

 

[seabob4]

Re: Battery Disconnect on Ground???

Just had a brain fart. Make sure the ground from your bilge pump (not the float switch, it has no ground) goes straight to the batt. That way your float will still operate the pump with the batt switch off...

 

[gmc1962]

Re: Battery Disconnect on Ground???

All the big equipment that I have owned breaks the ground with the master switch also. I guess it is pretty standard practice.

 

[fishrdan]

Re: Battery Disconnect on Ground???

Good question. Thinking about it, read any manual (well maybe not any)for working on an engine and what do they tell you to do first,,, remove the negative battery cable.

 

[StormRider01]

Re: Battery Disconnect on Ground???

That's the odd thing- dedicated hot lead to the bilge pump (it does have an auto float), but there's not a dedicated ground. I'm planning on adding a second battery with a off-1-2-both switch, and it would be a lot easier to leave the ground always connected than it would be to dig under the motor for a dedicated ground on the bilge.

If I use an off-1-2-both switch on the hot side, and leave the ground always connected, is that going to cause a problem?

 

[seabob4]

Re: Battery Disconnect on Ground???

A float switch is simply that...a switch. An interruption in current flow. There re no grounds associated with a switch.

Do this. Cut a wire to an operating pump or light. They stop working. Take both ends of that wire, strip the insulation back, and touch both ends together. They work. You are now the "switch", and the ground wire was never touched.

That's how a switch works...

 

[StormRider01]

Re: Battery Disconnect on Ground???

The problem here is that the master cutoff switch is on the ground side, and there isn't a dedicated ground from the bilge to the battery. So when the master cutoff switch is turned off, the bilge won't run because there's not a ground path to the battery.

So my options are to pull the motor to get at the bilge pump and wire a ground, or direct wire the ground to the battery, and put a cutoff switch on the hot side.

My question is if there's some reason why I should keep the master cutoff on the ground side, as pulling the motor is a lot more work

 

[fishrdan]

Re: Battery Disconnect on Ground???

To be honest, I've never heard of cutting the ground on a small pleasure boat, it's always the positive terminal that gets switched off. Though, I'm certainly no authority either...

 

[seabob4]

Re: Battery Disconnect on Ground???

Dan,
While unusual, it is not unheard of. It's basically 6 of 1, half dozen of another. They both work the same way, interrupting current flow. The only issue is the float, as I pointed out earlier...

 

[RickJ6956]

Re: Battery Disconnect on Ground???

Another issue with breaking the ground is the possibility of stray currents causing electrolytic corrosion.

 

[seabob4]

Re: Battery Disconnect on Ground???

All in all, your best bet is to remove the ground leads off the battery switch (assuming thats what your disconnect is) and placing them on a power post. Then run your positive leads to the switch so it will disconnect the batt(s) in the conventional way...

 

[dchris]

Re: Battery Disconnect on Ground???

The only reason I know of to pick the ground as opposed to the positive is to reduce posible shorts when removing the cables with wrenches or other metal tools. If your bump the frame or some other connection when you're on the ground side, no big deal. Lots of sparks on the positive side.