www.iFourWinns.com

To clarify my last post, when I say the isolator tested perfect I mean I had a loss of just under 0.6v which is expected.

The loss I am now chasing is either between the isolator and the switch, or at the switch itself.

As mentioned earlier I added a second #12 wire from the isolator to the switch and did not see any change in voltage at the switch. This is why I now suspect the switch is the problem.

I have seen the term tinned wire a few times now... What is this, and could it prevent a loss? I assumed the Tinned term was reference a thermal insulation on the wire.

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2004 - 288 Vista
Twin - 5.0 Volvo Penta GXi DP

Tinned wire refers to wire that was dipped in molten solder when it was manufactured (prior to insulator coating). Solder is a Tin/Lead alloy. This would provide a protective coating to prevent corrosion, even in salty moist air.

While plain wire conducts just as well when new, if it builds up oxidation on the surface, then it loses conductivity to it's joining parts (like crimped on connectors, and strand to strand). Also, with enough corrosion, the cross sectional area of the wire is reduced here and there and creates additional resistance. Therefore "tinned" wire is greatly preferred in the marine environment.

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"Knot Easy" 2000 Horizon 240 Volvo 5.7GS /SX
tow: 2017 Honda PILOT EXL-AWD
prev. boats:
'87 Chaparral 198CXL 4.3 OMC Cobra
'69 Jetstar 16ft Ski Boat, 115hp Yamaha
'68 Aluminum Jon Boat, 3hp Sears
'64 Water Wings

Yep! Also known as marine wire. Not that copper stuff that turns green.

Tinned wire is to me a necessity in a marine environment, esp for systems that your safety may depend on.

http://www.ancorproducts.com/en/search? ... tery+cable

This is what they should be using, at least for battery cables and other parts of the charging system.

I looked high and low for a tinned trailer wiring harness but to my knowledge no one makes one. So the next time I replace the wiring I'll make my own.

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88 Four Winns 200 Horizon
4.3 OMC Cobra-4bbl
2002 Walker Bay 10/2012 Suzuki 2.5
2008 Walker Bay 8

1998 Jeep Grand Cherokee 4.0/Selectrac
2007 Jeep Grand Cherokee 5.7 Hemi/Quadradrive II

What he said.

I had this same issue in my Vista. My Volvo alternators had a sense wire (orange), but it was connected to the output terminal of the alternator - which does little for you. Ideally it should be connected to the battery, so the alternator would put out enough voltage to compensate for the isolator and other losses.
I removed my isolator and replaced it with a VSR, I then rewired my switches so which ever switch is set to 'Parallel' is the engine that drives the VSR and charges the house battery. There is a lot of discussion (on other forums) on if it's okay to have two alternator outputs combined, but in general it's a bad idea - so when I go out, I put one engine on parallel and the other on 'on' or whatever the normal position is. You wont have this problem, with a single engine. While I was at it, I replaced the alternator output wire with a heavier gauge for proper voltage drop. I ended up replacing the starboard alternator because I broke one of the studs (of course).

The result? Much better charging voltage at the each battery. The dash still reads low (but higher than before) and the batteries get the correct voltage to get a proper charge. I also get a higher charge voltage out of the new alternator, but generally they are both fine. Since I no longer have any significant drop from the alternator to the battery, I left the sense wire where it was originally.

There is a breaker between the alternator and the isolator that you might want to look at as well.

I've added a battery charging monitor in the dash, so I can tell what's going on - so nice to see what's actually going on with the house batteries, and since it gets it's voltage reading directly from the battery, I don't really care what the dash gauges tell me.

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1969 Chris Craft Commander 47
1999 Four Winns 328 Vista - SOLD

Thanks for all of the info guys, it is very helpful.

I pulled the switch out and tested it to find it works as it should. I also tested each of the wires connected to the posts.

In a last effort to figure this out I disconnected the wire from the switch that sends power from the isolator/alternator. I saw over 14 volts at that wire with no load on it. Yee ha!

As a second test I ran a no.2 wire from the alt to the isolator, and from the isolator to the switch.... It was charding about 1 volt lower than what the alt was putting out.

I am going to replace this set of wires with No.4 today.

While working I also put another piece of the puzzle together... My alternator puts out 75 watts according to the info sticker, my isolator says max wattage 70 watts... WTF Fourwinns?

All in all a huge pain in the ass but I think this mystery has been solved.

I will likely ditch the isolator in the near future, but for now I need to spend less time wrenching on this boat and more time burning gas.

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2004 - 288 Vista
Twin - 5.0 Volvo Penta GXi DP