[C320-list] Battery Isolation

[Robert Seastream]

My setup is similar to Jeffs', but has an echo charger rather than an  
ACR to keep the start battery up.

Bob Seastream
Intuition # 906


On Apr 9, 2009, at 4:00 PM, <catalina at thehares.com> wrote:

> For what it's worth,  I use the Blue Sea ACR to do this.  It's a very
> versatile device and can be used for a number of different purposes on
> board.  (like auto-disconnecting the fridge if the house bank  
> voltage drops
> too low).
>
> My ACR simply connects the house bank to the starting battery when a
> charging source is present at the house bank.
>
> My alternator Feeds the house bank directly and my shore power charger
> feeds both house and starting battery.
>
> What's not an issue:
> ====================
> * Voltage drop/undercharging of the starting battery due to the diode
> junction drop isn't significant.  Remember, the starting battery is  
> not a
> deep cycle device and under normal circumstances is almost never  
> drawn down
> more than a tiny bit.  So it is normally recharged within a few  
> minutes.
>
> * Signal Noise.  Your Alternator, VHF, Autopilot, Radar circuits  
> introduce
> far more noise than these relays could ever hope to do.  In short, you
> won't hear it in your onboard Stereo if that's the concern.
>
> Now all this assumes that you wire the ACR (or other device) so that a
> charge source on the *HOUSE BANK* feeds the starting battery (and  
> not the
> other way around).  If you want to charge your house bank from an
> alternator feeding your starting battery, then that's a bit different.
> Factors such as how much current can this ACR carry (and for how  
> long), how
> much voltage drop happens across the ACR, possible undercharging of  
> the
> deep cycle house bank etc. come into play since fully recharging  
> deep cycle
> batteries is a longer more complicated process.
>
> All that said, it's extremely simple to wire an ACR to isolate the  
> starting
> and house banks, but depending on how your starting battery is wired  
> and
> operates may alter some of the minor details.
>
> Cheers!
> -Jeff Hare
>
>
>
> On Wed, 8 Apr 2009 07:59:02 -0700 (PDT), jelliott at landspring.net  
> wrote:
>> I am in the process of modifying my electrical system, and am  
>> curious as
>> to how others electrically isolate the house bank from the starting
>> battery.
>>
>> I have two 4D's under the settee paralleled as my house bank, and a
>> separate  starting battery located in the port lazarrette.  Both are
>> connected to independent channels of a Xantrax Truecharge 20.   The  
>> house
>> bank is monitored with a Link 10.
>>
>> The banks are still not electrically isolated; I assume this is a  
>> result
>> of a common connection to the alternator?  How do others handled  
>> this?  I
>> understand there are battery isolators that do this?  Any advice on  
>> how
> to
>> "break" this return circuit (if that's the cause) would be  
>> appreciated.
> I
>> am not very interested in adding a second switch which I know some  
>> have
>> done.
>>
>> Thanks,
>>
>> Julian
>> Polaris #340
>