Easy Ac/Dc

Easy Ac/Dc serves as a forum for the discussion of boat wiring concepts, products and issues - many of which are generated by reader’s questions.

If you have a boat wiring issue that you would like us to tackle, please send us an email at kevin@easyacdc.com.

You are also welcome to browse the existing posts and add your comments to any articles that you like.

Or, if you’re trying to track down info about a more specific category, please check out the list of various subjects on the right side of this page.

Again, we welcome your questions and suggestions relating to new topics as well. Please send us your ideas for boat wiring topics that you would like us to address.

We hope that you enjoy your visit here. Please come back often.

Hello Kevin,

My problem is that I have 24 foot pontoon boat with a 15 hp Mercury that continues to drain my battery.

I have to disconnect the negative cable after each use to keep the battery alive. Is there a way to find what’s draining this battery?

Thanks for your help on this.

Leon

Leon,

The easiest way to solve you boat wiring problem is to use a digital meter that can measure DC current. Something like this one from Radio Shack would work great.

To troubleshoot your system:

1. Disconnect the negative lead on your battery
2. Turn off all devices on the boat
3. Select DC amps on your meter
4. Connect one lead from the meter to the battery negative post
5. Connect the other meter lead to the negative battery cable
6. Observe the current – a few milliamps will be normal, a few amps will cause the battery to die quickly
7. Disconnect components that are not turned off until the meter reads a few milliamps.

Most of the time, you will discover that the problem is the stereo does not shut down completely until you hold the power button down for a period of time. Adding a stereo switch that completely shuts the stereo down is the easiest solution.

Another option is to add a battery switch like the ones from BEP. This would immediately solve your problem.

Thanks,

Kevin

Good morning Kevin,

Yesterday you suggested that I get a digital meter from Radio Shack and test my battery and that it would probably be the radio. Well you were right.

If I unhook the radio the meter reads .51. If I hook it back up it turns on when I touch the leads from the battery to the neg. cable. and reads 268. Did they wire the radio wrong and is this something easy to fix?

Thanks for your help

Leon

Leon,

Most stereos used on boats were originally designed for automotive use. They have two power wires. One (usually yellow) is the constant/memory power. It is connected to an un-switched 12v supply. The other power wire (usually red) is connected through the key switch. When the key is turned off, the stereo completely powers down.

Especially on outboard powered boats, it is rare to have the switched (red wire) stereo power wire connected to the key switch.

You can use one of your accessory switches to turn off the power to your switched (red wire) stereo power.

Another option is to remember to power down your stereo completely when leaving the boat. It usually involves holding down the power button on the stereo for 3 to 5 seconds. Your stereo owner’s manual or the internet will have the instructions to do this.

Thanks,

Kevin

Hello Kevin,

I have had a lot of problems with the electrical system on my 94 Hydra Sport 2100WA.

The tilt trim motor was working great and then it started acting like it was low on juice and then stopped tilting the motor up or down. I took both batteries out and charged them and still the same result.

I would think if the motor failed it would do nothing or make no sound. Is this a normal result of the tilt trim motor failing?

Regards,

Chance

Chance,

Outboard motor trim motors are continuously under water. Often, their seals break down over time, water penetrates the motor, and it is destroyed.

The good news is that most power trim motors are easy to remove. They are located between the engine mounting brackets. Raise the engine by releasing the manual override and remove the trim motor from the tilt/trim mechanism.

Be sure to have a good seal when installing the new/rebuilt trim motor - or you may find yourself repeating the entire project way too soon!

Thanks for writing.

Kevin

Hi Kevin

I own a 1975 30ft Reinell with twin crusaders.

The boat has two batteries with a 4 position battery switch and a built in AC charging system for the 12vdc.

My question concerns wiring the positive and negative leads from the charger. Do I bypass the 4 position switch so the batteries are always being monitored and fully charged?

If you could send me a simple diagram of how it is best to wire the charger I would appreciate it. Also my charger is as old as my vessel, so if it would be best to upgrade please let me know.

Thank you for your time and knowledge.

Bud

Bud,

The best way to wire a charger into a boat wiring system with a battery switch is to connect the charger to the battery side of the switch. This can be done by connecting the charger outputs to Battery 1 and Battery 2 on the switch, or directly to the batteries. The charger ground can be connected to the battery negatives or the boat system negative buss.

I like the Guest Line of battery chargers. Something like the 2633A would give you 30 amps of charging ability.

But, no matter which Guest unit you choose, make sure you add ignition protected circuit protection within seven inches of your connection to battery switch or battery positive. This can be accomplished with an ignition protected breaker or with an ATC (closed) fuse and holder.

I hope that this is helpful. Thank you for writing.

Kevin

Hello Kevin,

I’m trying to wire up some wiper motors.

We have three motors and three switches. On one switch there is a relay activating the washer pump. What I want to do is to put a momentary on/off switch at a closer location to the helm since the switches are a pain to activate in rough seas.

What I’m having a problem with is the park side of the wiper motors. I can’t seem to get them to work together on either the momentary or original switches.

Ashley

Ashley,

Your boat wiring should be set up so that:

• Each wiper motor has its own circuit protection.
• Each switch is independently powered.
• Each wiper motor has an independent park circuit.

If wired properly, when a wiper motor is turned on the run wire is connected to the park wire internally. Connecting multiple wiper motors with a single pole momentary button will cause wipers to almost never park. As long as one of the wipers is moving, all run wires are energized and the wipers will keep going.

One solution is a triple pole momentary button. Each wiper has an independent circuit coming off of the switch to prevent 12v feedback.

Another solution is a single pole switch with 2 relays. The switch actuates one wiper and latches both relays. One relay powers one wiper and the other relay powers the other.

Thanks,

Kevin

Kevin,

Thanks for your help with my earlier question. It has been raining every time I have time to go out to the boat, so have not had a chance to look any further for the fuse box.

I do have another question. I have a couple of VDO automotive gauges from an old VW I ran when I was a lot younger. These include a volt and amp gauge that I would like to mount in the boat.

I have a good idea of how to connect the volt gauge, but am not a hundred percent sure as to how I hook up the amp gauge.

Can you help?

Robert

Robert,

The volt gauge should be a simple boat wiring project.

1. Connect a black 16 awg wire from the ground position on the gauge to the boats ground system.
2. Connect a purple 16 awg wire from the positive position on the gauge to the accessory position on you ignition switch.

The amp gauge is not as easy.

To perform properly, the amp meter needs to be connected in series with your alternator output. On a stern drive or an inboard application, the alternator is easily accessible.

But, on an outboard, accessing the alternator is difficult, and connecting an amp gauge in series is even more so. You would need to cut the alternator output wire on the engine and run two wires from the amp gauge back to the engine alternator.

Amp gauges are rare on boats. They are complex to connect and add long alternator output wires that cause voltage drop and other potential hazards.

Most boaters and builders simply rely on the voltmeter. If the voltage is higher while the engine is running, you know the alternator is working. If the voltage is lower and continuing to drop while the engine is running, you know the alternator/battery/wiring has a problem.

Thanks,

Kevin

Kevin,

I have a 1987 Larson Senza 220 with a Ford 460.

Most of my gauges are pegged, although he fuel and trim gauge only peg when I turn the key on. The boat will run fine but doesn’t want to shift in neutral and that should be because the rpm’s are incorrect.

Would you have any idea what my problem could be?

Thanks,

Nathan

Nathan,

It sounds like your boat wiring problem is either a disconnected ground for the gauges or a damaged wire harness.

All of your gauges should have a ground wire connecting them together. This ground wire should be connected to the boat’s ground system. I would temporarily connect a wire from the negative of your battery to your gauge ground. If this doesn’t solve the problem, it’s time to start looking for a damaged wire harness. The fuel gauge will go to Full, the oil pressure to max, and the temp to hot if their sender wires are grounded. The trim gauge will go down.

If you cannot find a damaged wire, check each sender.

Fuel Sender

1. Remove the pink wire from the fuel sender.
2. With the key on, if the gauge stays at empty, then the sender is bad.
3. If the gauge stays at full when the key is on and the pink wire is disconnected, then the fuel sender wire is grounded between the gauge and the sender.

Temperature Sender

1. Remove the tan wire from the water temperature sender on the engine. Your engine may have 2 temperature senders. One is for the gauge and one is for the overheat alarm. Remove one at a time.
2. With the key on, if the gauge stays at cold, then the sender is bad.
3. If the gauge stays at hot when the wire(s) is removed then the temperature sender wire is grounded between the gauge and the sender.

Oil Sender

1. Remove the light blue wire for the oil pressure sender on the engine. Your engine may have 2 oil senders. One is for the gauge and one is for the low pressure alarm. Remove one at a time.
2. With the key on, if the gauge stays at low, then the sender is bad.
3. If the gauge stays at high when the wire(s) is removed then the oil pressure sender wire is grounded between the gauge and the sender.

Trim Sender

1. Unplug the two position trim sender connector on the engine.
2. With the key on, if the gauge stays at high, then the sender is bad.
3. If the gauge stays at low when the wire(s) is removed, then the trim sender wire is grounded between the gauge and the sender.

Solving your ground/sender boat wiring problem should clear up most of your problems. As for your engine, it may have a shift interrupter that is being affected by your grounding problem.

Thanks for writing,

Kevin

Just last week, I suggested that one of our readers check out the new boat wiring site, EzAcDc. Now, it turns out that these guys are getting a lot of attention from other marine electrical sites as well. Here is a recent posting from one of them:

“…very excited about the recent launch of EzAcDc. These guys could easily become the internet’s premier source for boat wiring systems and marine electrical components. Even with just their initial offering, they appear to be an excellent resource for boat owners.

EzAcDc offers engineered boat wiring solutions including:

• Boat Wiring Harnesses
• Marine Electrical Panels
• Marine Pump Systems
• Marine Lighting Systems
• Marine Horn Systems

We recommend their products and services without reservation…”

With this sort of recommendation, I couldn’t resist spending a little more time at the site myself. And, I’m happy to report that the rave review seems to be well deserved.

EzAcDc is a sister site to several other retail locations with excellent reputations. These other sites sell everything from marine carpet and pontoon parts to high-end boat seating. As you would guess from the name, the newest member of this diverse family specializes in marine electrical systems.

Ok, but why the rave? Well, what EzAcDc is doing is engineering high-production OEM style solutions for low volume (one at a time!) consumers. That is, they seem to be offering well thought out - and relatively easily installed - solutions to common boat wiring issues including such previously tricky jobs as harness and panel replacement or, as I mentioned last week, the total rewire of an old switch panel.

Given the reputation of its sister sites and the obvious thought that has gone into their products, EzAcDc should prove to be a valuable resource for all of the readers of this site.

Kevin

Hello Kevin,

I have a 1999 Sprint 215 deckboat. I need a diagram for wiring a 12/24 volt battery to a trolling motor. Can you help?

Thanks in advance,

Leon

Leon,

I did a little search for you at some boat wiring sites and was able to find this link to 12/24 volt battery wiring.

Hopefully this helps.

Thanks for writing,

Kevin

Kevin

I have a Refrigerator that runs on 12 volt, 110 volt and LP Gas.

According to the manual, the 12 volt and 110 volt are two different elements but both require 125 watts.

I have a 1000 Watt inverter -12 volt to 110 volt - but in trying to run the 110 V on inverter it shuts off & on indicating a overload. How can that be if it’s only 125 Watt required ? The inverter works fine on other applications, e.g., 100 watt Bulbs.

I need help. What am I not seeing or knowing ?

John

John,

I doubt if you are overloading the inverter.

My first idea would be that your inverter is not capable of producing a pure sine wave output. Instead of being a sweeping curve like swells on the water, the wave form looks more like something you made on an “Etch a Sketch”. Or, the electronics in the refrigerator may be causing some form of feedback to cause the inverter to shut down.

Would it be possible to supply more info on the refrigerator and inverter?

Finally, I have not seen refrigerators that have separate 12v and 110v systems. Usually, the base refrigerator is 12/24v dc and has a rectifier that converts the 110v down to 24v dc. If this is the case on your unit, you would be converting 12v dc to 110v ac and then back to 12v dc.

Thanks,

Kevin