[C320-list] 4D Batteries

[P.F. Ross]

Art,

A potential problem with simply hooking up your charged Group 27 battery to
a dead 4D, is that that battery pair will soon assume a voltage level
somewhere between the two, perhaps not leaving you with enough voltage to
push the current needed for your starter.

A better setup, albeit one that requires a fair amount of work, is to have
the reserve Group 27 battery on its own circuit through the battery switch
with the two 4Ds in parallel as the house battery.  There is much
documentation on the website as to how other owners have done this.

I have always found marinehowto.com a very helpful site, so you may want to
take a look at this article:
https://marinehowto.com/1-2-both-battery-switch-considerations/

Frank Ross
Beta Wave #206
Naples, FL

On Tue, Apr 16, 2024 at 9:30 AM Arthurpiotrowski via C320-list <
c320-list at lists.catalina320.com> wrote:

> Hello everyone and thank you for your input, great discussion. My question
> is about a separate battery kept for emergency use. I have one as well,
> group 27, with jumper cables stored nearby on the boat. I never had to use
> it, i think I would just connect it to one of my 4D battery in parallel to
> jump it and be able to crank the engine. Any concerns here?
>
> -Art Piotrowski
> C320 #330
>
> Sent from Artur’s phone
>
> > On Apr 14, 2024, at 9:57 PM, Troy Dunn via C320-list <
> c320-list at lists.catalina320.com> wrote:
> >
> > The short answer to your original question is simply no.  It is
> unrealistic
> > to expect a single 4D battery to power your energy needs for more than a
> > day or so at anchor.   A typical 4D is going to give you about 110 Ah of
> > usable energy at 50% depth of discharge.  The typical fridge is going to
> > draw about 2.5Amps per hour on average (obviously a lot of factors here).
> > Add in all your other basic comforts like lights, and radio, etc and you
> > will be pushing the limits of both 4D batteries and risking a call to
> > TowBoat US for a jump start.  Our current setup gives us  232 Ah of
> usable
> > house bank energy and that is just enough to get us through 2 days at
> > anchor assuming we were fully charged when we left the marina and a 4-5
> > hour sail with no alternator use.   (we have a seperate group 27 battery
> as
> > a reserve for emergencies only).    Unable to answer your question about
> > best 4D.   For me the best 4D is not having one on the boat.    But
> that’s
> > a debate for a different post.
> >
> > Troy Dunn
> > Hull #514
>
>