[C320-list] Battery Isolation

[Jeff Church]

Julian,

Just to be clear, the alternator is disconnected from the starter and 
wired to the isolator, but the starter is still wired to the same spot 
on the battery switch.

Here is a link to my picture posting site. Click on the wiring diagram. 
The 320 wiring is similar to the 387 except that I have 2 battery 
switches and chose not to parallel the house batteries.

http://picasaweb.google.com/SailCentral

I don't think undercharging is a problem if you use a Schottky isolator 
instead of the typical silicon diode isolator. I spoke to people at 
Xantrex, Blue Sea, Charles, and a few other sources about overcharging 
the start battery. Without going into detail, I'll just say that they 
explained how the resistance of the batteries naturally prevents it from 
happening. Jeff Hare can probably explain it better than I can.

JeffC


jelliott at landspring.net wrote:
> I've found lots of opinions on diode-based isolators vs. relay combiners,
> and unfortunatley comments tend to follow who's selling them. I've gone
> back and forth today on which direction is best. Talk of voltage
> mismatches, under or over charging, etc. is definitely confusing me. Work
> has definitely suffered...
>
> Your installation that routes the alternator-to-starter circuit thru the
> isolator answers a question I had as to how the banks would be electically
> isolated.  The literature I've read has not make that clear.
>
> Maybe I should just get a folding prop and be happy.....
>
>
>
>   
>> Good info. I looked all over for a Schottky diode isolator and didn't
>> find out that Guest made one. It also didn't occur to me that relay-type
>> devices could create RF noise. I just found the Guest unit (#2530) at
>> Pyacht.com for about $140.
>>
>> I recently installed a Sure Power Schottky-diode isolator when I
>> installed a starting battery on my 387. According to several sources,
>> using an isolator is a better approach than using any of the combiners
>> or other relay-type devices. The biggest problem with a combiner/relay
>> is that when the charging device initially starts and the combiner
>> closes, the depleted house bank can immediately draw a lot of current
>> from the  starting battery. Some of the devices like the Echo Charger
>> might not operate that way, but you should check on that before buying
>> one. The advantage of the combiner is that it is easier to install and
>> less wire ($$) is required.
>>
>> In order to install an isolator you will need to remove the wire that
>> connects the alternator to the starter motor, and run a #6 wire from the
>> alternator to the input terminal on the isolator. Then from the #1 and
>> #2 output terminals on the isolator you run wires to the battery switch
>> #1 and #2 terminals, or directly to the house and starting batteries.
>>
>> Good luck.
>>
>> JeffC
>>
>>
>>
>> jelliott at landspring.net wrote:
>>     
>>> I'm learning more... These are relay-based devices; Blue Sea tech
>>> support
>>> says they may induce RF noise if installed at the panel vs. at the
>>> battery
>>> (not desirable in my case).  Have you experienced this?
>>>
>>> The Guest isolators use Schottkey diodes, which induce a load (and
>>> corresponding heat), but don't suffer the potential RF problem.
>>>
>>> As usual, there is a tradeoff...
>>>
>>> Julian
>>>
>>>
>>>
>>>
>>>       
>>>> The Yandina is the one I used (mine is a WM re-label of this product.)
>>>> It's
>>>> as simple as described. The Blue Seas Relay will definitely do the
>>>> trick
>>>> as
>>>> well...
>>>>
>>>> Regards,
>>>>
>>>> Jon Vez
>>>> Solstice #582
>>>>
>>>> -----Original Message-----
>>>> From: c320-list-bounces at lists.catalina320.com
>>>> [mailto:c320-list-bounces at lists.catalina320.com] On Behalf Of
>>>> jelliott at landspring.net
>>>> Sent: Wednesday, April 08, 2009 4:09 PM
>>>> To: C320-List at Catalina320.com
>>>> Subject: Re: [C320-list] Battery Isolation
>>>>
>>>> John,
>>>>
>>>> I see WM has a Blue Sea Systems Starting Isolation Charging Relay which
>>>> seems to do the trick.  Is that what you installed?
>>>>
>>>> Also seen similar items from Guest and from a company called Yandina
>>>> (http://www.yandina.com/NewCatalog.htm).
>>>>
>>>> Looks like this fits the bill with a fairly straightforward
>>>> installation.
>>>> Almost too simple to be real...
>>>>
>>>> Julian
>>>>
>>>>
>>>>
>>>>
>>>>         
>>>>> Julian,
>>>>>
>>>>> I have the exact setup you describe. I used a battery combiner from
>>>>> West
>>>>> Marine. It's a simple device that you simply wire to each pole on the
>>>>> back
>>>>> of your current switch--one wire to the '1' and the other to the '2'.
>>>>> It's
>>>>> about the size of a match box and takes a couple of minutes to
>>>>> install.
>>>>> It
>>>>> will combine the batteries when motoring via the alternator and
>>>>> isolate
>>>>> them
>>>>> when not receiving a charge. Is the 'easy' solution to this
>>>>> problem....
>>>>>
>>>>> Regards,
>>>>>
>>>>> Jon Vez
>>>>> Solstice #582
>>>>>
>>>>> -----Original Message-----
>>>>> From: c320-list-bounces at lists.catalina320.com
>>>>> [mailto:c320-list-bounces at lists.catalina320.com] On Behalf Of
>>>>> jelliott at landspring.net
>>>>> Sent: Wednesday, April 08, 2009 10:59 AM
>>>>> To: C320-List at catalina320.com
>>>>> Subject: [C320-list] Battery Isolation
>>>>>
>>>>> 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
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>           
>>>>         
>>>
>>>
>>>       
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