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My battery switch has melted 2 years in a row and I don't know why

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The A/B switch has melted from being hot, twice. they both still worked but I would like to change what ever I need to before the season.

It is a dual battery setup with a single outboard Yama 115.

The wires do not show signs of over heating.

Should I add battery isolator switch or charging relay?

 

Any ideas where I should start? I appreciate any advice

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You sir could have many problems.  Are these well known blue sea switches or aftermarket  amazon ebay buys ?  Even well know. Blue sea switches fail and have had recalls . Contact blue sea and they will provide a new one if it falls into it serial number wise. These switch are suppose to trip if anything major happens. They have a amp rating.  You could have installed the wrong one.  Could be pulling to many amps. 

 

 

For two to have melted I would have to assume this to be a wiring issue. Fuses didn't trip which is another issue so safe to assume some wiring to be damaged.  

 

Imo your a one motor setup . I would start from scratch  and rewire your boat. You have been lucky twice to not burn to the ground.  Wires have been heated up twice now . 2 storke motor states wiring to probly be  30 plus years old. 

 

 

Post alot of pictures of all connections and components. Wing nutz  and not having amp breakers on troll motors  are the two big ones I see that create this issue. 

 

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Thanks for replying,

The switches both were Perko switches, and I was thing replacing with a Blue sea switch, Have they fixed the issues?

The boat is small CC so there isn't a lot to replace, I fish with my young son so safety is most important.

 

The motor is a 04 four stroke,

Is there a brand you recommend for the replacement components? 

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My 25’ Penn Yan always needed sacrificial anodes every 6 months, mechanic said grounds and or corrosion in wiring, this was a freshwater boat only. When we needed to change my downriggers with wire would sing

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  • 2 weeks later...

Things melt due to higher amperages creating heat.  You get higher amperages from loose or  corroded fittings.

 

Before rewiring, I'd pull the lugs off all the cables, see what you have.  Cut back and re-crimp/solder if the cables themselves look free of corrosion.

 

If I had to bet, you've got corrosion under the lugs creating enough heat to start a fire, so doing nothing is not an option.  As mentioned, you've been lucky to date

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I’d be curious to see how many amps the generator on the motor is putting out. If that’s ok I would measure the resistance in the wiring. You can find the ohms per foot of resistance in a NEC book if you can find one. As mentioned the anodes may be suspect as well. 

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Wiring from the batteries to the switch, and from the switch to the starter should be sized for the amperage draw (on cranking) of the starter itself. Wiring from the alternator to the Battery Isolator (higher than 120amp output) or the SI-ACR (start Isolation Automatic Charging Relay 120amp max alternator output) should be sized for the alternator amperage output.  See wiring diagram and Wiring sizing chart.  I personally always select for 3% maximum loss.

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DC_wire_selection_chartlg.jpg

Edited by FlatWing
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  • 2 months later...
On 3/29/2024 at 7:03 PM, GoneCoastal said:

I’d be curious to see how many amps the generator on the motor is putting out. If that’s ok I would measure the resistance in the wiring. You can find the ohms per foot of resistance in a NEC book if you can find one. As mentioned the anodes may be suspect as well. 


The highest current is when starting the motor. Once running, the motor gets voltage directly from the alternator (correct me if I’m wrong). While running, the generator supplies voltage to the battery. Is there some kind of load limiting circuit when charging the battery similar to an external car charger? (Around 6 amps)

 

As mentioned, make sure the specifications of the switch are acceptable for the expected loads under normal operation. 
 

If so, then it could be grounding. The current needs a return, that is ground. If some of your grounds have high resistance, the current will find the least resistive path and may create a condition where components of the circuit are exposed to currents higher than spec.

I love when we make way past the breakwater at first light and head out, there's nothing better, the whole rest of the world just melts away for me.

(*edited - member formerly known as 'windknot')

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Agreed something is definitely wrong with the wiring on your boat, a Yamaha 115 doesn't draw that much current to crank over and the alternator doesn't put out that many amps either, I would be surprised if it is more than 50 amps. 

I would go over all the battery wiring very carefully, it can be corroded under the insulation and you won't know it, you most likely have a loose, corroded connection somewhere or an internally corroded battery cable. You can use an amp clamp to see how many amps are flowing through a wire but if it's getting hot you already know you have a problem. Start with the basics. Battery terminals, battery cables, cable terminations at the battery, starter and ground, as well as the battery switch terminals. 

BTW do NOT use wing nuts on your battery terminals, they get loose and cause guess what, high resistance/low voltage! Make sure ground connection at the engine isn't corroded. Same thing with the common cable that goes from the battery switch to the starter solenoid. 

2007 Jeep Grand Cherokee Limited 5.7 Quadradrive II

1998 Jeep Grand Cherokee Laredo 4.0 Selectrac

1988 Four Winns 200 Horizon 4.3 OMC Cobra

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