On Sat, 19 Jul 2008 09:43:01 -0700 (PDT), "
wrote:

On Jul 19, 12:23*am, Bruce in Bangkok
wrote:
...
During your bulk charging stage what voltage are your batteries
reading and how many amps are you charging at? ...

I generally cycle the batteries on passage where I try to get away
with one hour of charging a day. We support two 12 volt, air cooled
compressors (fridge and freezer) and the auto pilot and nav lights,
RADAR, radios &c. Our solar array is usually partially shaded while
under way so we have less input there.

Keeping in mind that no two days are alike and I'm not working off of
data logs or anything: In the morning we generally see ~12 volts or a
little less on the batteries (they are always under load) and the
acceptance rate plus load is more than 200 amps. The voltage rises
slowly to 14.2~14.4 (depending on what the temp is). After about and
hour I typically shut down the engine and the acceptance plus load at
14ish is in the low teens. For the first third or so of that the
charge rate is greater than 50 amps. My take is that I'd kill
standard sized alternators pretty fast asking them to go full out for
half an hour (integessing the extra time to 50 amps) plus another 45
min of topping off and it would take more time to get to the same
charge rate. Down the list a ways you mention a cat that charges its
batteries 3 hours a day. I would find that intolerable. It seems to
me that the trick to reducing charging time is to have a good sized
alternator and know when to stop charging. It's unusual to be
offshore for more than a week without a day of calms and on those days
you can top the battery off while getting a propulsion boost form the
motor. YMMV.

-- Tom.


No, Perhaps I should have explained in more detail. On the 4 day trip
because of having little wind the Cat motored between 3 - 4 hours a
day.

Bruce-in-Bangkok
(correct Address is bpaige125atgmaildotcom)