Sparks and smoke from battery cable.

[alandry100]

Hi all - had a bit of a scary experience today. I have just finished a new tank install and am preparing to de-winterize - hooked up the battery and was testing things out, everything seemed to be working tilt and trim, lights, navigation, bilge, but when I went to turn it over, it did but there was sparks shooting from the power connection about a foot from the where it enters the engine upon inspection there is a hole in the wire covering and it looks like some of the wire is missing. No fuses were tripped. I'm wondering if the wire got nicked at some point this winter. Question is - do I need to replace the whole harness. Can I cut back, splice, and re-shrink wrap what is there? It was a double wire - positive and negative wires. Looks like the negative is unharmed but I might do both of them.

[boatnamesue]

No need to replace.  If spliced in correctly the connection will not increase resistance.  I actually had to do the same thing a few weeks ago.

Since the area you're cutting out is close to the engine, if you have extra cable length battery side you could just cut out the damaged wire, pull through engine, and mount on starter.  If not, splice is your next option.  Your battery cable wires are most likely 4 gauge.  Splice with metal butts.  Here's the possible issue you'll have.  Crimping heavy gauge wire requires a very large set of crimpers.  They are as big as bolt cutters.  They are very expensive, and since you'll only be making 1 or 2 connections, it's a waste of money to buy.  You'll need to find a marine service shop that will loan you one.  My local shop charged me $5 for the day.

Before making butt connections, double up the heat shrink wrap.  Cut the top wrap longer than the bottom, so it overlaps.  Make crimp connections.  Apply heat to wraps, bottom first then top.  I then recommend painting on a couple layers of liquid electric tape.  It's overkill, but hey, you've experienced what happens with electricity. 

[alandry100]

Thanks - and a cut in the wire would likely cause that correct?

[wingtime]

Looks like something took a bite of the wire. I'm sure some strands inside are damaged. The sparks you saw were not from a short but from high amperage build up in the damaged portion of the wire. The damage causes an area of high resistance heating up the strands and causing them to burn. The problem will only get worse. If this is a computer controlled motor you could fry the EMM. I would NOT put a butt splice in the main battery leads. The first reason not too is this area is subject to lots of flexing from steering, tilting etc. That will loosen the splice in time. The second reason is the high starting amps will cause a huge resistance build up at the splice. If your power leads are long enough I'd shorten them and put new ring connectors on them. I'd inspect the cables carefully and feel for weak spots indicating broken wires inside. If you find ANY replace the cables.

[alandry100]

Thanks wingtime - I actually just measured and I'm pretty sure there is enough spare cable to cut and re-lug. The bolts look like 8mm so 5/16" should do it? I don't know if the motor is computer controlled - it's a 70 hp 2005 Yamaha 2 stroke.

[alandry100]

Well - I tried to borrow a crimper from a couple of places in town, my mechanic and an boat/snowmobile dealer of a friends and they both solder their battery cables, so I had to go out of town -20min away to a marina where a friend is the head mechanic. They had a crimper and he would let me borrow it over night. I went down to get the lugs, a filter, and a the crimper. Luckily my buddy was there - he took a look at the cable and ripped it apart. It was corroded at least 8" toward the engine from the break. He had another Yamaha cable that he just pulled off a 300hp - 4AWG and just the right length. I spliced the ends of my factory cable to it - I turned it over a few times and sounds good and not warm at the connection. It does make me nervous that the splice is in the engine - but then again it is out of the elements there.



Turns out the old battery connector was spliced to lengthen (was in the rigging channel and I never really considered it until now) ~10' of factory to ~4' of 4AWG which was much bigger than the Yamaha wires. I would have switched to new lugs,  and I still may , but I will have to get the proper connectors because they are very small in comparison to what you can get at the marine shop. I'm guessing I will have to go through Yamaha.

[wingtime]

Sounds like there was some damage to the insulation that allowed water to get in a corrode the wire.

Don't go to Yamaha... Just order some wire from either of these guys:

https://gregsmarinewiresupply.com/index.php?route=product/category&path=18

https://www.genuinedealz.com/custom-cables

Either one of them will make you up custom length battery cables that are very high quality tinned marine wire.

[RickK]

I used Greg's - he packages every order himself it seems. Great quality.