[C320-list] generator question

[Stephen Cox]

Bob,

Ohms law is right but batteries don't absorb power at the rate you put it
in, some of it goes to heat and gassing.  Also, the charger won't be putting
out 14v for the whole time.  Once you get into the absorption phase the
charger will hold the voltage constant and the amps going in will reduce as
the battery takes on more charge.  See http://www.batteryfaq.org/  Click on
"Car and Deep Cycle Battery Frequently Asked Questions (FAQ) 2009" and then
go to Section 9, for more information than you will ever need.

Stephen Cox
Tegwen #1141

> -----Original Message-----
> From: c320-list-bounces at lists.catalina320.com 
> [mailto:c320-list-bounces at lists.catalina320.com] On Behalf Of 
> Robert Seastream
> Sent: Monday, February 08, 2010 12:26 PM
> To: C320-List at Catalina320.com
> Subject: Re: [C320-list] generator question
> 
> The generator is more than enough to power your 120 VAC 
> powered battery charger, and then some.  We'll take your 
> conservative guess and presume your chargers max output is 12 
> VDC @ 10 amps.  Ohms' law states that P = E x I (or watts = 
> voltage x current).  If your power consumption is ~120 
> AH/day, or 1440 watts (12 volts X 120 amps =1440 watts), then 
> it should take the charger ~10 hours to replace the 120 AH 
> (12 volts X 10 amps/hour = 120 watts X 12 hours = 1440 watts) 
> you drained from the batteries.  However, your charger output 
> is likely around 14 VDC, so the recharge time will be 
> somewhat less; perhaps ~8 hours?  I think I've got Ohms' law 
> right but others on the list may be better versed than I, so 
> if I'm all wet, someone please step up.
> 
> Bob Seastream
> Intuition # 906
> 
> 
> On Feb 7, 2010, at 7:07 PM, Andrew Santangelo wrote:
> 
> > Are you using the generator to only charge your batteries? 
> If so you 
> > may want to consider just putting in a higher output 
> altenator on the 
> > engine. Far more efficient, no need to carry two fuels, no loss of 
> > space due to the generator, and a cheaper solution overall. I have 
> > sailed my C320 extensively with lots of electrical items 
> and this has 
> > worked fine.
> >
> > Now if running AC, hair dryer, TV, microwave in the open 
> water or at 
> > anchor that is another story.
> >
> > Best regards,
> > Andrew
> > C320 Dawn Treader
> > #333
> >
> > Sent from my iPhone
> >
> > On Feb 7, 2010, at 2:59 PM, Paul Adison <pjaarch at verizon.net> wrote:
> >
> >> I am considering the purchase of a Honeywell 1000i 
> gasoline generator 
> >> for the times I am cruising.  It is a 1000w generator producing 
> >> 7.5amps @ 120volts.  I am assuming that i am using 120ah 
> per 24hour 
> >> period give or take while under sail.  I am assuming that 
> the battery 
> >> charger is 10amps and not 15 although I don't know.  Can 
> anyone tell 
> >> me how long I will need to run the generator at night to 
> charge the 
> >> batteries back up?
> >>
> >> Paul Adison
> >> S/V "Rough Draft" _/ )
> >> C320 #722
> >>
> >>
> >>
> >>
> >>
> >>
> >>
>