[C320-list] Battery Isolation

[Kirk McCullough]

Jeff

I just had a survey in February for insurance reasons. The surveyor checked
out all electrics mainly from a safety angle and gave me a clean report.

What would be the concern with this arrangement?

Kirk
#124

-----Original Message-----
From: c320-list-bounces at lists.catalina320.com
[mailto:c320-list-bounces at lists.catalina320.com] On Behalf Of Jeff Church
Sent: 18 April 2009 18:41
To: C320-List at Catalina320.com
Subject: Re: [C320-list] Battery Isolation


Kirk,

Catalina installs the optional starting battery that way on the 387. 
They just parallel the house batteries and connect the starting battery 
to #2 on the battery switch,  without using an isolator or combiner. I'm 
not sure what a picky surveyor would say about that.

JeffC


Kirk McCullough wrote:
> Is it not just about as easy to leave the house and starting batteries 
> un-combined or un-isolated and just select which one to charge with 
> the 1-2-both switch? That's what I do and the starting battery is 
> always good to go. I don't use it for anything but starting and even 
> then if I happen to be on house while at anchor I often just use them 
> to start the engine.
>
> I didn't see or maybe didn't properly understand the benefit of the 
> ACR when it was explained to me recently, so I just bought a new Blue 
> Sea 1-2-Both switch when I bought new 4D deep cycle batteries last 
> fall, just to be sure I wasn't getting any leakage across my old 
> original Guest 1-2-Both I replaced it. All is good.
>
> Kirk
> #124
>
> ----- Original Message ----- From: "Jeff Church" <jc387 at att.net>
> To: <C320-List at Catalina320.com>
> Sent: Friday, April 17, 2009 7:35 PM
> Subject: Re: [C320-list] Battery Isolation
>
>
>>
>> Bob,
>>
>> Me too. That's why I thought as soon as the combiner closes, current 
>> from both the charger and starting battery would flow through the 
>> house batteries until the resistance of the house bank increased.
>>
>> What would happen if there was a shorted cell in the house bank? With 
>> a combiner couldn't the starting battery discharge thru the shorted 
>> house battery?
>>
>> I was also told by the guys at Charles that since the discharged 
>> house batteries present the least resistance, most of the bulk and 
>> absorption charge will flow thru them, so the smaller starting 
>> battery will not over charge.
>>
>> Jeff
>>
>>
>> Robert Seastream wrote:
>>> I thought a discharged battery has an extremely low resistance, thus 
>>> presenting a near short to any charging source.
>>>
>>> Bob Seastream
>>>
>>>
>>> On Apr 17, 2009, at 10:00 AM, <crashley at gte.net> wrote:
>>>
>>>> At the risk of offending Orlando again, I'll take a crack at this. 
>>>> When you
>>>> turn the charger on into an open circuited or discharged house 
>>>> battery, it
>>>> takes a little while (several seconds) for the battery voltage to 
>>>> climb up
>>>> to the initial charging voltage which should be about 14.4V. This 
>>>> delay is
>>>> because the battery looks like a large capacitor. The ACR has a 
>>>> time delay
>>>> in it so when it senses that the house battery voltage is 13.5V (or 
>>>> higher)
>>>> the timer starts and 30 seconds or so later the relay closes. At 
>>>> this point
>>>> the house battery is at 14.4V and the starting battery is at 12.7V 
>>>> (open
>>>> circuit voltage) so it will start charging too. I think the only 
>>>> possible
>>>> issue here is that if the house battery is a lot larger than the 
>>>> starter
>>>> battery, which is normally the case, the starter battery will see a 
>>>> longer
>>>> "absorb" charge time than it needs, but I don't think this is a big 
>>>> problem.
>>>>
>>>> Long live space junk!
>>>>
>>>> CR Ashley
>>>> Rosebud C320 Hull #882
>>>>
>>>>
>>>>
>>>>
>>>> -----Original Message-----
>>>> From: c320-list-bounces at lists.catalina320.com
>>>> [mailto:c320-list-bounces at lists.catalina320.com] On Behalf Of Jeff 
>>>> Church
>>>> Sent: Wednesday, April 15, 2009 10:57 AM
>>>> To: C320-List at Catalina320.com
>>>> Subject: Re: [C320-list] Battery Isolation
>>>>
>>>> Chris,
>>>>
>>>> Like I said, maybe I didn't totally understand what the guys at 
>>>> Charles and
>>>> PS (2 independent sources) told me.
>>>>
>>>> Why wouldn't the ACR sense 14 volts, or more, the moment that the 
>>>> charger
>>>> switches on? My battery monitor does. I know that there will be 
>>>> some voltage
>>>> drop due to the discharged house, but the charger output is
>>>> 15 or 16 volts initially.
>>>> .
>>>> Jeff
>>>>
>>>>
>>>>
>>>> crashley at gte.net wrote:
>>>>> I disagree. It doesn't surprise me that the guys who make the
>>>>> expensive MOSFET devices will tell you what they did. The ACR will 
>>>>> not
>>>>> close until the battery being charged reaches 13.5V. The starter
>>>>> battery should be sitting at around 12.7V before that so it will not
>>>>> discharge into the higher voltage battery, it will actually start
>>>>> receiving charge current as well. I agree that the ACR will allow
>>>>> current to go in either direction, but in this case it should not. 
>>>>> The
>>>>> only time this might occur is if the charging source goes away in
>>>>> which case the ACR will open when the house battery drops to 
>>>>> 12.7V, so
>>>>> it should not allow the starter battery to discharge too much into 
>>>>> the
>>>> house battery since 12.7V is a fully charged state for lead acid 
>>>> batteries.
>>>>>
>>>>>
>>>>> PS: I am an EE and have been designing battery chargers and
>>>>> dischargers for spacecraft for 28 years. Talk about $$$$!
>>>>>
>>>>> CR Ashley
>>>>> Rosebud C320 Hull #882
>>>>>
>>>>>
>>>>> -----Original Message-----
>>>>> From: c320-list-bounces at lists.catalina320.com
>>>>> [mailto:c320-list-bounces at lists.catalina320.com] On Behalf Of Jeff
>>>>> Church
>>>>> Sent: Tuesday, April 14, 2009 10:53 PM
>>>>> To: C320-List at Catalina320.com
>>>>> Subject: Re: [C320-list] Battery Isolation
>>>>>
>>>>> When I was designing my setup I spoke at length to several engineers.
>>>>> The techs at Charles and Perfect Switch (PS makes MOSFET isolators
>>>>> ($$$$) for the military and NASA) told me about this particular 
>>>>> problem.
>>>>>
>>>>> My understanding is that when the charger comes ON, the ACR senses 
>>>>> the
>>>>> voltage and the switch closes. At that point current flows from any
>>>>> available source towards the path of least resistance. In this case
>>>>> the house batteries are the path of least resistance and current will
>>>>> flow from both the charger and the starting battery to the house
>>>>> batteries until the resistance in the house and starting batteries
>>>> equalizes.
>>>>>
>>>>> An isolator does not allow any current to pass from one battery bank
>>>>> to the other.
>>>>>
>>>>> I'm not an EE so maybe I got it wrong.
>>>>>
>>>>> JeffC
>>>>>
>>>>>
>>>>>
>>>>> crashley at gte.net wrote:
>>>>>
>>>>>> JeffC,
>>>>>>
>>>>>> The Blue Sea Systems battery combiner relay (ACR 7600) has a voltage
>>>>>> sensor so it will not close until the house battery is being charged
>>>>>> at 13.5V so the starter battery should never discharge into the 
>>>>>> house
>>>>>>
>>>>> battery.
>>>>>
>>>>>> CR Ashley
>>>>>> Rosebud C320 Hull #882
>>>>>>
>>>>>>
>>>>>> -----Original Message-----
>>>>>> From: c320-list-bounces at lists.catalina320.com
>>>>>> [mailto:c320-list-bounces at lists.catalina320.com] On Behalf Of Jeff
>>>>>> Church
>>>>>> Sent: Wednesday, April 08, 2009 5:59 PM
>>>>>> To: C320-List at Catalina320.com
>>>>>> Subject: Re: [C320-list] Battery Isolation
>>>>>>
>>>>>> 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
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>
>>>>
>>>
>>>
>
>