Reverse Polarity Accident

[WNY Tony]

I need some advice.

My new-to-me boat was setup with two batteries in the rear stoarge units, one on the port side of the boat, one on the starboard. There were two batteries because he had run electric riggers. My downriggers are manual, and therefore I only need one battery in the rear for starting and for accessories. I chose to move the extra battery to the bow as I installed a trolling motor up there, and this weight distribution is better for the boat it seems.

Now this is where I ran into trouble... I took all of the accessory electric wires that were run to the "extra" rear battery, and I snaked them back to the starting battery. When I went to hook them up to the battery, I mistakenly hooked the accessories up in reverse polarity. Within 5-10 seconds something was generating smoke somewhere in the rear of the boat/motor. I obviosuly freaked out, and disconnected everything, and let the dust settle. Upon review, the motor starter cables were correctly hooked up, and accessories were hooked in reverse polarity. I ran into trouble because I mistook my positive starter cable for the motor as a negative because it was black (it only had a small red dot onto it), and just plopped the black negative accessory cables right onto it without double checking anything.

I am hoping for some help. I don't understand why this would occur given that nothing was powered on in the entire boat? I insepcted all of the wiring I could see, and everything looks good, no discoloration at any terminals, no insulation missing, etc. I tested the electronics, lights, radio, fish-finder, bilge pump, livewell pumps, all turned on after I let everything cool off and hooked it up properly. I did test the power trim/tilt on the motor which works fine, but I have not started the motor yet (in the garage), frankly scared that I did something to it. Can anyone shed some light on what I may have done. Is it possible to have damaged my motor at all? Sorry for any ignorant questions, 12V setups have never been my strong suit.

Thanks.

[King Slammin]

That is a $350 mistake. Trust me, I let the magic smoke out of my alternator earlier this year doing the same thing. Take her to a mechanic or if you have a voltage meter, test it while running to see if you have 14 volts.

[WNY Tony]

I will have to look into that.

I did just roll the boat out and fired the motor up. Everything looked fine and worked fine including the tachometer, which I thought had to have a working rectifier as well to operate. This may be wishful thinking on my part.

[lost a lure]

You let the smoke out of the wires. What accessories did you connect in reverse?

[WNY Tony]

I am not 100% certain of what accessories were in reverse, but I believe it was the bilge pump, fish-finder, and lights (at some point, several of them merge into a havier gauge wire). The wires for the motor starter were setup correct, but I guess that would not matter once something is in reverse polarity? There was an inline fuse on the positive side of the accessory cable.

[WNY Tony]

What does "letting the smoke out of the wires" exactly mean? That sounds less expensive than an alternator (insert prayer here).

[lost a lure]

Letting the smoke out means the wire melted the insulation and smoked. If you hooked the negative accessory wire to the battery positive that was a direct short to ground.

[dewey123]

some electricians will say everything runs on smoke and when you let the smoke out it is destroyed/dont work.

[jimski2]

Reverse polarity destroys the diodes on your alternator. It can be rebuilt with new diodes. Lights do not have a polarity problem unless they are the LED type and then I am not sure.. Electronics may have polarity protection. Positive wires directly grounded melt the insulation and could be shorted out now. That is why you install a fuse close to the battery terminal on your positive wires to things like your electronics.

My first check now would be to inspect the wiring especially where you noticed the smoke.

If a voltmeter shows above fourteen volts with the engine running, your alternator is OK.

[WNY Tony]

Great news! I checked voltage at the battery and at the alternator, and got 14.6 Volts in both locations while the motor was running. Battery Voltage when the motor was not running was 12.4V. From what I understand, this means that my alternator is OK?

I have inspected all my wires, and tested all of my electronic equipment, and those still work. Still scratching my head as to what would have cause the amount of smoke that was generated in such a short period of time.

I guess I will take it out this weekend for some extended use and see if anything materializes.

Should I check anything else at this point?

Thanks for the suggestions.

[Xxx]

If you are running a Mando alt. then 14.6 is perfect, 12.5 is a fully charged battery,12.4 close enough, a starter does not know polarity, so your good there also, if all circuits were closed then you should be in good shape!!! The smoke, well I would inspect wires for a bubbled surface if you see any thing like that replace that wire, the bilge pump is a permenent magenet motor, which means no fields to burn up and the same for the trim motor which also means their are fully insulated, so you are good there also! if you have any questions just ask and I will try to help,I've been in the starter&alt business for 30 years PAP

[Gator]

My buddy hooked the batteries up in reverse polarity last week and lo and behold we found a couple of blown fuses in the motor itself. I never realized that the alternator was fused, but one of the main mini-fuses under the hood was blown and when we replaced it, the alternator started working again. And hence we dodged the "$350 mistake"

[Knotlost]

You really need to check the wires on everything very carfully. You could have bear wire in several places, or the insulation on the wire may be crispy and easly broken off and cause problems when you dont want them.

The fact is you made someting smoke, so it burned or came close enought to count it as burning, and you need to find out what it was or dont use the boat. If you get out on the lake you could have big problems depending on your boat, and right now the water is too cold to bail into if your boat catches fire.

Get some red electirical tape and start taping the hot wires red, all of them. Idiot proof that aspect of the wiring or it will get repeated by some one. When you find the burnt wires replace them with marine wire.

[WNY Tony]

PK, thanks for the feedback. I guess I have a question: hypothetically, if I had some wire either positive or negative that was missing some insulation from it being burnt off .... what would be the worst case scenario now that I have the wiring setup correctly? Is it that I would be losing ground, blowing fuses, etc? Where does the risk of fire come into play now that it is hooked up correctly? I ask this not because I am questioning your statements, but rather I don't fully understand what the potential ramifactions could be of missing insulation. I understand if the wire diameter was reduced, it could generate more heat, but I don't fully understand if missing insulation leads to heat (and fire). Any feedback is greatly appreciated.

I was planning on taking the boat out this weekend on Honeoye to chase some walleye ... maybe rethinking that until I can look at each wire 100% inspection, etc.

Thanks.

[Knotlost]

The number one reason boats catch on fire, and burn is because of shorts in wiring, and insulation being burnt off is the number one reason for that.

What happens when the insulation is compromiseded, then the bear wire or a wire thats not insulated properly heats up because of normal use that well within its range; melts the plastic that its now near,or sets the wood on fire that its touching (very common in this type of failureur) because of a little normal movement that would nonormally be a problem, moves it into contact with its surroundings, and you have a fire.

Bear wire will cause a short, and shorts = heat (lots of it), and sparks, all a wonderful source of fire. With a fuse, you hope you have it fused properly so it will blow before the fire, thats why there are fuses; to prevent a fire.

But you have to make sure your fuses are all the right size (alot of fires start when a fuse blows and "dingle berry brain" just puts a higher rated fuse in to keep it from blowing). Fuse size based baced on wire size and load absolutely expecting the insulation to be in perfect shape. A fuse will blow long before the insulation starts smoking if its sized properly. Insulation thats not perfect on wires should be replaced.

Remember a fire is the worst problem on a boat even worce than a hole in the bottom.

Remember its your boat, if you invite a friend out and they go with you expecting to have a good time and some one gets hurt or worce; its totaly your fault becasue you didn't do diligents to find what burnt up. You will have to live with that, and thats not worth it, just find the wires thats smoked.

[Xxx]

A great rock band once said (ac/dc) bare wires cause fires!!!!