Kevin,

I just purchased this boat and the surveyor indicated the existing 10 amp, 1 bank charger was not suitable for marine use. So I purchased a marine 3 bank 15 amp charger (Canadian Tire Nautilus). Apparently every 5 minutes, it cycles through each bank and sends up to 15 amps.

• I connected one bank directly to Battery #3
• I connected second bank to post #1 on isolator
• I connected third bank to post #2 on isolator

Do you believe that this will work?

Shawn

Shawn,

The posts should not be connected inside the isolator.

A one in / three out isolator has 3 diodes inside. Internally, one goes from Post A to Post 1, the next from Post A to Post 2, and the last from Post A to Post 3.

When the alternator starts charging, it applies charge to the battery with the lowest voltage first. When that voltage rises to the second highest, the isolator allows current to flow to the lowest 2 batteries. When the combined voltage hits the voltage level of the highest voltage battery, the isolator allows current to flow to all 3 batteries. Usually this happens within seconds of engine startup.

The only time Posts 1,2, and 3 are basically connected is when the alternator is operating and the batteries are all at the same voltage.

Hope this helps,

Kevin

Kevin,

Please check out this drawing of my boat wiring.

So are posts 1, 2 and 3 basically connected on an isolator?

In other words, when the charger is sending power to bank #1 to charge, is it also going to post #2 and #3 ? I seem to have continuity between post 1, 2 and 3 on the isolator

Shawn

Hi Shawn,

Nice boat wiring diagram!

This will work great. If it cleans up your wiring and makes battery removal easier, I would consider connecting the bank for battery #3 to the isolator post 3.

Have a great weekend,

Kevin

Hi Kevin,

I am having A very strange problem on my 72′ Sunseeker that I can’t figure out.

I recentlly replaced all the overhead lights throughout the whole boat with L.E.D. lights. All of the lights are powered by 24 volts and are wired in series. I used 12 volt L.E.D.’s throughout the entire boat and they work fine.

I then started on the exterior of the boat, replaced all the lights on the arch, aft deck courtesy lights and the flybridge courtesy lights and they too worked fine. Ok enough of all that.

Here is my problem, The last lights I tried to replace were the port and starbord gunnels, I have nine lights on each side and they are controled by separate switches. I installed all my new lights and they work great for a couple of minutes and then they start flickering and then they stop, and then they start again.

This is driving me crazy!

Can you please give me some insight as to why this is happening ?

Thank You,

Keith

Keith,

Without looking at the system, I would guess that your flickering lights are being caused by a voltage drop problem.

The LEDs turn off when the voltage drops too low. As soon as the current draw goes away (the lights turn off), the voltage rises again and the lights turn back on. This causes in increase in current, a voltage drop in the wire, and the lights turn back off again.

Increasing the size of the boat wiring at least one AWG will probably solve your problem.

It sounds like you have a wonderful boat. Can you send me pictures of your project that I can post on the site?

Thanks,

Kevin

Kevin,

I have a question in regards to wiring my boat tachometer. I have a 1973 135Hp Johnson outboard V4 on a 1970 Glastron and the tachometer is not working simply because it’s not connected to the rest of the boat wiring.

So where do I start..? I’ll run all new wires, but to what? And how many wire leads will I need? Do I wire it into the throttle box, if so, to the ignition switch and how or do I have to run a set of wires to the motor directly?

Thank you,

Russ

Russ,

All the required wires should already be at your ignition switch/throttle box.

• Purple – Switched power from Key switch – Connect to B+ on your tachometer
• Gray – Tach signal – Connect to the S on your tachometer
• Black – Gauge ground – connect to the (-) on your tachometer

Hope this helps,

Kevin

Kevin,

Thank you kindly; you’re really prompt and it’s appreciated.  I can’t wait to get back under the dash and look for those contacts on the tach. 

Funny, I just had to replace my throttle cables last weekend (it snapped just past the no wake zone; not good, however we couldn’t dare tell our 4 and 5 year old boys that the party was over.  They were so excited to be on the boat for their first time, so we came up with a plan; my wife steered as I sat in the back with the motor and cables pushing and pulling on them until we got it down pretty good and off we went to finish out the fishing adventure; had a great day anyway) and I had the throttle box completely apart.  And so at the same time you just solved the two dangling wire mystery from below my throttle box. 

I look forward to opening the throttle box back open and hooking it up right and actually seeing the tach operable.  I’ll keep you posted and if I run into any other problems or question I’ll reach out again; great website…

Thank you again Kevin and sorry for that long story, but I couldn’t help it we are first time boaters and having a ball.

Russ

Kevin,

Please help. I have tried so many things and still cannot get it to work. Here goes.

Bought a boat a few months ago and the fuel gauge reads full.

• I replaced the sending unit and gauge with a matching set. Still full.
• Replaced the wiring, still full.
• Wired separately from the battery on a dual battery system. Here is how I wired it. The hot off the battery to a toggle switch then to the ‘I’ terminal on the gauge. Ground from the same battery to the ground terminal on the sending unit and also the ‘G’ terminal on the gauge. Also a new separate wire from the ‘S’ terminal on the gauge to the center terminal on the sending unit. Still reads full.
• I then bonded the ground wire to the motor. Still reads full.

I removed the sending unit and only 1/4 tank fuel. I put a meter across the center terminal of the sending unit to the ground side of the sending unit and I am getting constant continuity as I moved the float arm up and down.

What am I doing wrong or not doing at all? Is the new sending unit bad possibly???

I tried calling the boat manufacturer and they wont even talk to me as the boat is too old and their service manuals don’t go back that far. It is a 1993 Rinker 260 Fiesta Vee with a 5.7 liter Mercruiser that was replaced in 2005.

Supposedly, the fuel gauge and trim tabs quit working after the motor was replaced. Also, the lower unit trim quit working.

I checked power at the relays as a friend moved the trim switch and I had 12 volts there with the wire disconnected, but as soon as I touched it to the relay the voltage went to zero.

So, I completely rewired it directly off the battery also and it now works fine. It has blown a 30 amp fuse one time though. This is all I have done with the electrical on the boat.

Got any ideas what is going on? I would like to get my fuel gauge working.

Regards,

Scott

Scott,

Fuel Sender

It sounds like your replacement fuel sender is the problem. Full should be about 33 ohms and empty around 250.

Power Trim

Poor connections on a power trim system will give the voltmeter reading that you have described. There is 12 volts available at a very low current (enough to make your meter happy) but not enough when you have the high draw of your trim pump.

Hope this helps,

Kevin

We get a number of questions regarding the type of wire to use in boat wiring projects. Our recommendation is always to spend the extra money and go with tinned wire such as that offered in bulk by Ancor or in any of the premade boat wiring harnesses available at our partner site,

Now, to further reinforce this advice, William Lynch at eHow has written an excellent overview of the advantages of this truly superior product. It’s a good piece and well worth checking out.

Nick and Kevin

Hello Kevin,

I have a main engine, a kicker motor, and a on board charger all supplying charging voltage. Should I connect all those negative cables to the ground buss on my marine electrical system? And then, connect the positive engine and charger leads to terminal 1 of the boat battery switch?

Will I encounter any problems using this boat wiring hookup?

Thank you

Earl

Hi Earl,

Connect all of the grounds together at the ground buss.

Connect the battery charger to the battery side of the battery switch. Connect your engine(s) to the switched side of the switch.

When the switch is turned off, your on board charger will still charge the batteries but your other boat wiring will be turned off.

Hope this helps,

Kevin

Hello Kevin

I have enjoyed many of your posts and have decided to put an dc power outlet on my Four Winns Freedom 160, so I can use my GPS, charge my cell, etc.

I would really like it if there would be power without the engine on and I am curious to know if I can wire it through my ignition to accommodate that?

There are two wires, grey + and white -. Can you steer me in the right direction?

Gratefully yours,

Dwight

Dwight,

Four Winns usually puts a fuse block under the helm. This is a great place to connect your 12 volt receptacle and it has 12 volt power without the engine on.

Use one of the open fuses for your grey + wire and connect your white – wire to the negative buss. I would not use a fuse larger than 10 amps for a 12 volt receptacle.

Happy boat wiring,

Kevin

Kevin,

The navigation lights on my old boat stopped working.

The rocker on/off/on switch is bad. It has four .25″ spade conectors in the back. To replace it, I bought a DPDT rocker switch with six spade connectors. I put the boat wiring in the same locations as the old one but it does not work. What is the proper position for the wires?

Robert

Bob,

You will need to add two jumper wires to make your new switch work properly with your boat wiring.

• Power – connect to one of the center spade connectors.
• Jumper wire # 1 – connect from center spade connect above to the other spade connector
• Stern light – Gray/blue – connect to top right post
• Jumper wire # 2 – connect from top right post above to bottom right post
• Bow light – Gray/green – connect to bottom left post

Hope this helps,

Kevin

Kevin,

I want to put on a 36 volt trolling motor, replacing the 12/24 version that I currently have.

I have a two bank charger. After I add the third battery, can I still use the two banks on two of the batteries and then hook up a portable charger for the third?

Chris

Chris,

Yes. Your plan will work. BUT…remember that your portable charger is probably not ignition protected. It should not be used in a compartment where gasoline is stored.

Kevin