Kevin,

My boat wiring currently has a shore power charging system, and an alternator on the diesel.

I would like to add a 100 watt solar panel with regulator. How do I wire it to ensure that the three charging sources aren’t potentially “tripping” over each other if they happen to get used at the same time?

Thanks!

Stephen

Stephen,

Your batteries act as a giant filter.

Most marine electrical charging devices won’t trip over each other. When the engine is running, the alternator will be the dominate charging device. When plugged in, the charger will be in control. While on the anchor, the solar system will do all of the charging.

Hope this helps,

Kevin

Hello Kevin,

I currently have a 1991 26’ Macgregor Sailboat that is in need of shore power and while looking online I came across your partner marine wiring site.

The boat has a basic one battery DC setup to power its navigation lights, Radio, and interior cabin light but has no way of charging the battery since it’s primarily a “trailer sailor”.

I recently purchased a new Honda four-stroke outboard which has a charging feature that I have not connected since I mainly trailer the boat and charge the battery with a portable charger when I come home.

However, I’m in the process of moving the boat to a local marina with standard 30A service (west coast CA) and would like to add a permanent Guest style charger/maintainer, GFCI convenience outlets for a TV, laptop, portable heater, etc. and would like to see what options are available.

Also, if I were to go with one of your complete marine electrical shore power systems, how would I connect my outboard’s charging system to the battery without interfering with the AC connected battery charger? Can they both be connected at the same time or would I need some sort of switch (I wouldn’t run the two systems simultaneously).

Could I run the DC powered cabin light, radio etc. while the shore power is connected and charging the 12 volt system as well as any accessory connected to the convenience outlets?

I’ve also read about galvanic corrosion… would this be an issue since I don’t have any thru-hulls and raise my outboard when docked? As this is my first boat, any help with selecting the correct components and with getting wiring schematics would be greatly appreciated!!

Thanks

Ernie

Hi Ernie,

Our EzAcDc shore power system will easily accommodate any Guest style charger/maintainer, which could simply plug in to one of the outlets on the back of the panel assembly. Along with protecting itself, the front panel GFCI protects all remote outlets. Additional GFCIs are not required.

Your boat battery cables, existing boat DC system, and battery charger can all be connected to the battery at the same time. There is no need for a marine battery switch. Even though it will probably never happen, the battery charger can be on while you have Honda running and charging the battery. They are designed to be able to work together.

While you are plugged into AC, you can certainly run your DC equipment along with your AC TV, heater, etc. As long as your battery charger is large enough, it will be able to keep up with the additional DC loads. If you plan on running your DC equipment for extended periods of time while your battery charger is on, you may want to consider buying a charger that is large enough to charge the battery and run your DC equipment.

As long as you do not have any metal hull fittings, galvanic corrosion should not be a problem on your boat. Even though the GFCI will protect against most AC fault issues, please make sure your AC and DC grounds are connected together. Our AC shore power panel provides this ground wire.

Hope this helps,

Kevin

Kevin,

My 1990 Sea Ray Express has two 454 Mercruisers.

I have no voltage feed to my starboard alternator. The large red wire goes to the battery isolator,but I believe the alternator is powered up by a smaller red purple wire. Where does it come from? It has no voltage on it.

Any help is welcomed and gratefully accepted.

Bob

Hi Bob,

On a marine engine, if an alternator has an external excite wire, it is usually purple and is basically keyed ignition power. When ignition power is supplied to this wire, the alternator basically turns on. This type of alternator works better with a battery isolator because you are actually sensing the battery voltage and not the alternator output voltage.

If your alternator is self exciting and internally sensing, then the single red/purple wire is the “idiot light” wire. This wire goes to ground when the alternator dies. It is connected in series with an indicator light. IMPORTANT: If you apply ignition power directly to this post on this type of alternator, you will burn up the internal rectifier.

Determine which type of alternators are on your boat using an internet search and the model number on them. If they are self exciting and internally sensing, your alternator is dead. If they have an external sense wire, trace down the red/purple wire and determine where it is not making connection to the ignition wire.

Happy boating,

Kevin