[C320-list] Battery Isolation

[Jeff Church]

Julian,

Yes, most isolators that you'll find at marine supply stores use silicon 
diodes. The Schottky diode type will have a voltage drop of .15 to  .45 
volts. Silicon are typically rated at about triple that amount.

Jeff

jelliott at landspring.net wrote:
> Thanks Jeff.  As usual a picture is worth a thousand words.  I'll digest
> this in more detail tonight. The dual house bank idea is interesting; I
> may consider it once I master this topic.
>
> Am I to understand that isolators can come with standard Si diodes OR
> Schottky diodes,depending on the manufacturer?  I do remember from my
> first EE course back in the dark ages that Schottkys had a lower voltage
> drop.  So this must alleviate some of the perceived issues with using
> isolators (at least as explained by the relay advocates).  I guess I need
> to spend some more time with the tech support teams.
>
> I'm picking this up slowly (very slowly) but surely.
>
> Julian
>
>
>   
>> 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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