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
<<mailto:cnc-list@cnc-list.com>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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