Dear Kevin,

I am currently beginning my first boat wiring project, a total rewire of a small Owens cruiser from the late ’60s.

Here’s my problem:

The old wiring runs behind the original paneling and headliner. I could try dismantling everything to remove and replace the wires, but am concerned about damaging any of the woodwork. It’s old. It’s gorgeous. It would be a bitch to replace.

I don’t mind leaving the old wiring in place and just running a new harness, but that still leaves the problem of installing the new wires without causing any damage.

Any ideas?

RP

Dear Ron,

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Kevin.

Hi Kevin,

I’m an airplane guy who’s redoing the boat wiring on my brother-in-law’s 1972 22’ Reinell.

I have a couple of questions.

We ordered a boat horn and a Smart Battery Switch from EzAcDc yesterday. However, we only ordered the VSR thinking it was all we need but after looking closer I’m not sure.

The boat has two batteries and a manual 1/both/2 switch. Should I change our order to the complete Smart Battery Switch System?

This boat has an original one-wire Delco alternator. I want the following but I’m not sure how to achieve it:

• The ability to disconnect the alternator from the battery when the alternator fails (if this is not important than I’ll forget about it)
• The ability to turn on a warning light when the alternator fails (we removed the original ammeter but the 3 in 1 gauge we installed does have a volt meter)

Do you have any suggestions i.e relays or any other components I can use to achieve the above results? I wouldn’t mind upgrading to a more modern alternator if that solves the problem.

Any direction you can give would be greatly appreciated.

Kevin

Hi Kevin,

A VSR works best when you have a dedicated engine battery and a dedicated house battery. The VSR makes the connection between the two systems.

A conventional battery selector (Off, 1, 2, Both) controls which battery the engine is connected to but does not control which battery the house is connected to.

The key to our partner’s complete Smart Battery Switch System is the dual pole On/Off battery switch. This acts like two on/off battery switches combined into one body.

• When the switch is Off, only emergency devices are connected to the house battery.
• When the switch is On, the engine is connected to the engine battery and the house is connected to the house battery.
• When the engine is running, the alternator first charges the engine battery. When the engine battery hits 13.7 volts, the VSR connects the engine battery and house battery together and begins charging the house battery.
• When the engine is off, the VSR keeps the batteries connected until the battery voltage hits 12.6 volts. When it drops below 12.6 volts, the VSR breaks the connection and allows for enough reserve in the engine battery to start again.

I would not worry too much about a way of disconnecting the alternator if it fails.

In the event of an alternator failure, your system voltage would begin to drop. With the complete VSR system, once 12.6 volts is reached, the VSR will open the connection between the engine and house batteries. Your engine will continue to run until the battery voltage is below 10 volts. When the engine dies due to low voltage, you can turn the battery switch to the COMBINE position. This will manually parallel the batteries and allow you to start your engine and continue running until your battery voltage is to low to run the ignition system.

You will probably run out of gas before you completely drain two batteries running only a simple ignition system on a single stern drive.

Thanks

Kevin

Kevin,

With no generator or selector switch, my boat’s galvanic isolator is currently located between the shore power ground connection and the 110V ground bus. The 110V ground bus ties into the 12V negative bus and the boat ground (a steel pontoon).

I have recently restored my onboard generator and have installed a source selector switch (shore power or generator). I’ve read everything I can and I still can not identify to my satisfaction how to connect a galvanic isolator into an electrical system with shore power, an onboard generator, and a source selector switch.

The confusion (on my part) is that the battery selector switch being used has a separate connection for the ground wire from each source on what appears to be a solid bus bar connecting them. This suggests that both the shore power ground and the generator ground are connected and wired to the isolator inlet and the isolator outlet is wired to the 110V ground bus, the 12V negative bus, and the boat ground (steel pontoon).

Is this correct? Maybe the separate ground connections to the battery switch exist only to support the reverse polarity LED light, but it is still confusing.

Your guidance is requested.

Dave Freeman
Richland, WA

Dave,

The main reason for a galvanic isolator is to prevent stray current corrosion through your boat’s shore power connection. It basically induces enough of a voltage drop to prevent a galvanic cell from being created between your metal underwater gear that is electrically connected through your shore power ground wire to other metal gear in the same body of water – usually the dock.

To be effective, the galvanic isolator must break the shore power ground wire – the green wire between your inlet and your AC panel. All of the AC grounds on your boat wiring system should be connected together – Generator and existing AC systems.

You should have a single wire that connects the DC ground to your AC ground.

Hope this helps,

Kevin

Kevin.

Can you tell me the correct boat wiring for a galvanic isolator into an inverter/charger? Everyone in the marina has their own opinion, I just need a pro’s advice.

I need to know if the green from the shore power goes into the inverter and then to the 110 volt panel. Then does it go from the panel to the battery and then the engine block?

Thanks.

John

John,

The green wire goes from the shore power inlet to the galvanic isolator. From the isolator, the green wire goes to your inverter which is connected to the AC ground on your distribution panel. There should also be a wire between the AC ground and the DC ground (engine block)

Have a great day,

Kevin