I have a "Zap-Stopper", which is a $2 15 volt zener diode that used to sell for about $20 back in the day. It connects across the alternator and shorts out temporary transient high voltage spikes. I think there are no longer sold because a permanent over-voltage condition will cause them to melt and smolder. We melted one back in the day by forgetting to close the circuit breaker on the alternator and the regulator was tying its best to get some output. The smell alerted us before the alternator was done in. Joe Coquina C&C 35 MK I
From: CnC-List [mailto:cnc-list-boun...@cnc-list.com] On Behalf Of Russ & Melody via CnC-List Sent: Sunday, April 10, 2016 09:34 To: cnc-list@cnc-list.com Cc: Russ & Melody Subject: Re: Stus-List Automatic Charging --> alternator field Hi Dave, First a small primer on alternators. The spinning part of the alternator is called the field, charging power comes out of the stationary part. You apply a bit of power to the field, say 3 amps, and magically many times that amount comes out to charge batteries. Your questions involve field power. 1. - generally the key switch powers the field too, so when you inadvertently turn it off you simply "turn off" the alternator too. No Damage. (The exception is if you have a self exciting regulator which powers itself, magic again, but still no damage. 2. - some BATT switches had an internal switch which "break" the field power while switching. If the old one had this feature then the PO wired in the external switch instead of eliminating it. Or she knew what she was doing after taking a Nigel Calder course and decided to wire in a field switch which she would use every time she switched banks (even though she bought the "make before break" switch). Long story short: verify it's in the key "on" circuit and leave it on unless you are switching battery banks while engine running. Cheers, Russ Sweet 35 mk-1 At 06:09 AM 10/04/2016, you wrote: A followup on Josh?s post: 1. A couple of times I have accidentally turned the key switch off while the engine was running and my brain was elsewhere. I immediately turned it back on again. I have noticed any problems resulting from this, but I don?t know what the symptoms would be if I had damaged something. 2. In addition to the rotary 1, 2, All rotary, I also have a on/off toggle switch next to the rotary that must be also turned on. I don?t know what is wired to it, so does anyone know what is likely to be the purpose of that switch? My previous boat only had the rotary. Thanks- Dave On Apr 6, 2016, at 3:56 PM, Josh Muckley via CnC-List <cnc-list@cnc-list.com<mailto:cnc-list@cnc-list.com>> wrote: It is safe to switch between 1-ALL-2 as long as everything is working as designed. You also have to be very careful not to accidentally overshoot to the off position. What isn't safe is turning the ignition switch to off while the engine is running, or as mentioned turning the batt switch to off while the engine is running. The only concern about mixed types of batteries is various chemistries. A leaf acid starting battery and a lead acid deap cycle battery are the same chemistry so you're fine. Josh Muckley S/V Sea Hawk 1989 C&C 37+ Solomons, MD
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