[C320-list] Battery Isolation
Jeff Church
jc387 at att.net
Tue Apr 21 13:00:22 PDT 2009
Kirk,
I'm not sure. I'd have to ask that picky surveyor.
I guess the question arises in my mind because everyone I asked
suggested that I use either a combiner or isolator. No one even hinted
that I should just use the switch to control charging. I'm not saying
that your solution is wrong, I just wonder what the "experts" or a
surveyor would have to say about it.
JeffC
Kirk McCullough wrote:
> 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
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>
>>>>
>>
>
>
>
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