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.

Kevin,

I have a 20′ Bass Tracker pontoon that came with one marine battery.

The single battery runs the 70hp old Johnson, radio, livewell pump, navigation lights, boat horn, tilt etc. I also have a 535 Hummingbird fish finder and a trolling motor that are connected to a dedicated deep cycle narine battery.

What can I do to keep both marine batteries charged without pulling them out of the boat and drag them to my in-house charger? Where my boat sits, there is no electricity to have a Guest charger hooked up.

Will solar charger work for fish stuff and basic charge from the alternator for crank battery? Or is there something else that you would recommend?

Thank You

John

John,

Before adding a solar charging system, I would try a battery switch system. Our friends at EzAcDc have a great automatic battery switch system that will allow your engine alternator to charge both marine batteries while underway, but keep them separate while your trolling motor is discharging your deep cycle battery.

With this setup, your engine would be the only item connected to your starting battery and all other equipment on your boat would be connected to the deep cycle battery.

This automatic battery switch system also has a single ON/OFF switch that controls the two batteries. This means that when you turn the switch OFF, all power draws are disconnected from the battery. This really helps because a charged battery will last for several weeks without needing a recharge if all loads are disconnected.

When you turn the switch ON, both battery systems are connected. The engine is connected to the cranking battery and the DC systems are connected to the deep cycle battery.

When you start the engine, the alternator charges the cranking battery to 13.7 volts. The automatic battery switch system’s “brain”, a voltage sensing relay (VSR), which resides between the cranking battery and the deep cycle battery completes the connection and now the alternator is charging the cranking battery and the deep cycle battery.

When the engine is turned off, the battery voltage begins to drop as DC devices are used. When the battery voltage drops below 12.6 volts, the VSR breaks the connection between the cranking battery and the deep cycle battery. The deep cycle battery continues to discharge, but your engine battery has enough reserve capacity to start the engine.

Most solar chargers have a very low output. (.5 amps max). If you don’t have a battery switch in the system, the memory circuits of your stereo, hummingbird, and other devices can easily exceed this .5 amps and defeat the purpose of having it.

Kevin

Good morning.

I’ve searched the files and although interesting and informative on many topics, I couldn’t find anything close to my particular question/situation. Perhaps you can help.

I have a 28.5 Hunter sailboat with two Group 27 wet cell batteries controlled via a Guest Battery Selector Switch (1,2,Both, Off).

I’m moored on a can and augment the minimal battery usage (bilge pump) while away with a 6-watt solar panel fed through an interior cigarette lighter. This system has worked thus far (5 years), but has no voltmeter to indicate state of charge on either battery. There’s an Autopilot in the plans, so knowing the state of charge on each battery will be warranted.

The Guest switch is within a foot of the batteries and easily accessible. I’d like to install a single 12 volt voltmeter above the Guest switch (analog or digital, depending upon price & features) but cannot find any references to how this should be wired to the Guest switch.

I’m assuming the meter will read (monitor?) the battery (or batteries) selected, i.e., #1 or #2 or Both. Am I missing something or is this possible?

Thanks for your help with this.

Hope you enjoyed your Thanksgiving.

Take care.

Jay

Jay,

Adding a Voltmeter to your boat wiring is a great idea.

The voltmeter requires two wires to read voltage.

Ground

• Your two batteries have a common ground.
• I would connect a 16awg black wire from the negative terminal on the back of the gauge to your ground buss (or battery negative)

Power

• Connects to the battery + through a selector switch to all individual battery voltage readings.
• You will need a switch similar to this one and a switch cap similar to this one. This is a momentary switch to prevent excess battery draw.
• I would connect a 16awg red wire from the positive terminal on the back of the gauge to the center terminal on the back of the new switch.
• If you want the gauge to light up, connect a 16awg red wire from the positive terminal on the back of the gauge to the light terminal on the back of the gauge. When voltage is checked, the gauge will light up

To complete the installation:

1. Connect a 16awg red wire from the bottom post of your new switch to BAT 1 on the back of your battery switch.
2. Install an in-line fuse holder and fuse as close as possible to the battery selector switch. This fuse should be 5 amps or less.
3. Finally, connect a 16awg red wire from the top post of your new switch to BAT 2 on the back of your battery switch.

With your battery switch in all positions except BOTH, your new voltmeter switch will read independent battery voltages. Up on the switch will read battery 1 and down will read battery 2. If you have the switch in the BOTH position, your meter will be reading the combined voltage.

Hope this helps,

Kevin

Hi Kevin,

I’ve got a Freeman 23 which I have just moored in a marina without an electric hook-up. I recently bought a solar panel, a leisure battery and an inverter in an attempt to be self sufficient to run a boat heater and TV etc.

The instructions on the inverter say I need to earth the unit. Would you be able to advise where within the boat I could safely earth the unit? I’ve read I need to be careful about causing corrosion if it’s wired incorrectly and also potentially giving people an electric shock.

Hope you can help.

The equipment is as follows-

• 80w Solar Panel
• Sonnenschein GF12110V Deep Cycle Gel Battery 200Ah
• 2000w Inverter

Regards,

Steve

Steve,

This is a great boat wiring question. People are always nervous about what to do with the green wire.

Some the basic rules to follow when working on AC wiring on a boat.

1. Use dual pole breakers if you are not sure on polarity
2. Do not connect the AC neutral with the AC ground
3. Connect the AC Grounding (earthing) to the boat’s DC negative buss
4. Your inverter should have AC out (Hot,Neutral,Ground) and DC in (12+,ground). It may or may not have an earthing stud.
5. Connect the AC out to your AC distribution system.
6. Connect the DC in to your battery or battery management system
7. If the inverter has a ground stud, connect a wire (12 awg green) from the stud to the DC negative buss.

The biggest problems with corrosion occur when your incorporate a system like this with an electric hook-up. A galvanic cell is created with the steel dock pilings, the shore power ground wire, the grounding wire between your AC panel and your engine ground buss, and the zinc (or other sacrificial metal) on your boat. You boat corrodes away to protect the steel in the dock.

If you remove this wire, then you create a major shock hazard.

Let’s say, for example, that your refrigerator (AC and DC) has an internal fault that connects the AC to the DC. Every part of the DC system, including the engine and drive, are energized at 220 volts. The water below the boat is too much resistance to trip the refrigerator breaker. A person swimming near the boat has no chance. I believe that you would only need 2 volts/foot to paralyze a person in the water. With 220 volts in 7 feet of water, you are dissipating over 30 volts/foot.

Moral of the store, keep the green grounding between your AC and DC system. You may have corrosion but you greatly decrease your chances of killing somebody. And that’s not even a close trade-off.

Follow the manufacturer’s instructions for circuit protection for both the Solar panel and the inverter. If connecting to the battery, make sure you are using ignition protected fuses and breakers. If the inverter is in the engine room, be sure it is ignition protected as well.

Thanks,

Kevin