Join Date: Apr 2006
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The zap stopper uses one commercially available diode, which can be bought for about $5 if you know where to look. Add some crimps, some heat shrink, a retail and distirbutor markup, and the $25 retail price isn't crazy. But not ethat if you have diodes "hanging in space" in your wiring harness, the vibration from the engine WILL break off their leads and they will become useless inshort order. They need to be solidly mounted to something.
I'd also suspect one or more of the alternator diodes fried, possibly not the regulator. Conventional alternators are 3-phase or 6-phase and if you blow one or two diodes, you get some reverse voltageinthe output which tricks a cheap voltmeter into seeing just a lower DC voltage level. AND--HEADS UP--if you blew a diode the battery will be discharging back through the blown diode. When you come back to the boat next week, the battery may be dead as a result of this, so you want to either check it now, or make sure the battery positive is disconnected completely from the alternator. (If you leave the DC power totally OFF when you leave the boat, that's safe.)
Either way, a replacement regulator or diode frame (these days you replace all the diodes as anassembly) from a shop should be a $50-75 repair including the time and part. Double that from any kind of "dealer". If you can diagnose it and order the part itself,a $25-50 repair.
Battery isolators and the like...a good idea to make the process more idiot proof. Any one of us can get tired, sunstruck, or just plain dopy and make an oops. Oops-proofing the battery selection isn't a bad idea.