Advice on motor boat wiring

[jon_bailey]

My newly acquired fast fisher/cruiser has some interesting wiring that I’d welcome your advice on. It has two batteries, house and starting, with 3 isolater switches for house, starting or linked. It has Mercury Verado outboard with Smartcraft controls and gauges and a three position ignition switch. There is no shore power.

Wiring as below.

Directly to house battery:
Bilge pump, manual and auto

Switched House battery (i.e. live as soon as house battery switched on):
Fuel gauge
Depth gauge
12V sockets
Gas alarm

Switched House battery through separate control panel
Interior lights
Fridge
Water pump

Switched house battery through separate individual switches
VHF
Chartplotter
Fishfinder
Wipers
Nav lights
External light
Anchor light
Anchor windlass

Switched house battery through Acc position on ignition
Nothing connected

Switched starter battery through On position on ignition
Engine controls
Trim
Engine gauges

So, three questions:

1) Whenever the house battery is turned on so are fuel and depth gauge, so running down battery, when are your fuel and depth gauges turned on?
2) What do you have connected to the Acc position of your ignition switch?
3) Anything else you would improve/change

Thanks

Jon Bailey

 

[VicS]

My newly acquired fast fisher/cruiser has some interesting wiring that I’d welcome your advice on. It has two batteries, house and starting, with 3 isolater switches for house, starting or linked. It has Mercury Verado outboard with Smartcraft controls and gauges and a three position ignition switch. There is no shore power.

Wiring as below.

Directly to house battery:
Bilge pump, manual and auto

Switched House battery (i.e. live as soon as house battery switched on):
Fuel gauge
Depth gauge
12V sockets
Gas alarm

Switched House battery through separate control panel
Interior lights
Fridge
Water pump

Switched house battery through separate individual switches
VHF
Chartplotter
Fishfinder
Wipers
Nav lights
External light
Anchor light
Anchor windlass

Switched house battery through Acc position on ignition
Nothing connected

Switched starter battery through On position on ignition
Engine controls
Trim
Engine gauges

So, three questions:

1) Whenever the house battery is turned on so are fuel and depth gauge, so running down battery, when are your fuel and depth gauges turned on?
2) What do you have connected to the Acc position of your ignition switch?
3) Anything else you would improve/change

Thanks

Jon Bailey

Presumably in the above you mean from the "switched starter battery through ACC position on ignition "

The only thing I'd change maybe would be to wire the fuel gauge via the ignition switch, perhaps from the engine battery via the Acc position, otherwise along with the engine gauges.

presumably you can switch of the depth gauge locally if not required.

 

[William_H]

The battery switching arrangement seems ideal It may have a voltage sensing relay across the linking switch or do you have to operate that when the engine is running for charging then open that switch for isolation? If you don't have a VSR then that would be ideal to do that job automatically. ie go to the boat operate engine power and house power switch then forget until you leave the boat. As VicS said move the fuel guage to the engine on circuit. good luck olewill

 

[jon_bailey]

Presumably in the above you mean from the "switched starter battery through ACC position on ignition "

The only thing I'd change maybe would be to wire the fuel gauge via the ignition switch, perhaps from the engine battery via the Acc position, otherwise along with the engine gauges.

presumably you can switch of the depth gauge locally if not required.

The Acc position does switch the house battery via a relay.

The depth gauge cannot be switched locally. I assume the logic is that depth alarm will sound when at anchor?! If not used at anchor then should it be linked into the ignition switch along with the depth gauge?

 

[pmagowan]

As per VicS the switches sound like mine, which I think I picked VicS's brain about at the time. Mine are from BEP and are a start, house and emergency parallel and have a VSR included in the cluster. The only thing I have connected permanently live is the bilge pump. The sounder is connected to the house via an instruments switch on my switch panel. My fuel gauge is connected to the ignition so that first click turns it on as long as the start switch is on. I tidied up my whole electrical system so that everything that required switched went through one panel. the bilge pump has a switch here for manual on but can not be turned off without physically disconnecting from the battery (I have a wooden boat and so it is in a permanent state of sinking!).

 

[jon_bailey]

The battery switching arrangement seems ideal It may have a voltage sensing relay across the linking switch or do you have to operate that when the engine is running for charging then open that switch for isolation? If you don't have a VSR then that would be ideal to do that job automatically. ie go to the boat operate engine power and house power switch then forget until you leave the boat. As VicS said move the fuel guage to the engine on circuit. good luck olewill

Voltage sensing relay - that's a new one on me, and a good idea. The linked switch is simply that, a switch that links the two positive terminals, so I start with them unlinked and then link once the engine starts and is charging. Then have to unlink when engine off to avoid running down starter battery. The VSR would be much better and easier.

In practice, is there any difference between a VSR and a split charge relay?

Thanks for the advice

 

[VicS]

Voltage sensing relay - that's a new one on me, and a good idea. The linked switch is simply that, a switch that links the two positive terminals, so I start with them unlinked and then link once the engine starts and is charging. Then have to unlink when engine off to avoid running down starter battery. The VSR would be much better and easier.

In practice, is there any difference between a VSR and a split charge relay?

Thanks for the advice

By split charge relay I think you mean a relay which closes when it senses that the engine is running and the alternator generating. It can use the warning light circuit.

A VSR senses the volts at the battery which is directly charged from the alternator. When this rises to a predetermined value it closes to connect the other battery.

Marginally better because it allows the first battery to, at least partially, re-charge before closing.

 

[pmagowan]

I liked the idea of the start battery having priority with the VSR. I can let the house go down a bit but would not fancy the start battery running out.