[C320-list] Battery Charger Wire Size

[Karl Mielenhausen]

Remember the cautions when using the MRBF as shown in this document...
http://bluesea.com/viewresource/640
ONLY ONE ring terminal allowed per fuse. That's why you will need more
then one. Of course that allows you the option to fine-tune the fuse
sizes.

Karl

On Sun, Aug 12, 2012 at 7:36 PM, Welch, Myron D <myron-welch at uiowa.edu> wrote:
> Karl,
>
> Thanks for the suggestions. The MRBF terminal fuses started out as a way to finally fuse my charger, something that has been on my "list" for several years. As I make the changes and upgrades to install the start battery, I am putting them on the alternator to house battery wire, both battery connections from the ACR, and other places I find that need protection. Yes, our factory wiring does seem incomplete. I'm pleased that so many on this list are available to help.
>
> Myron
>
> Sent from my iPad
>
> On Aug 12, 2012, at 7:16 PM, "Karl Mielenhausen" <kmielen at suddenlink.net> wrote:
>
>> Each lead from my Xantrex charger is fused at the battery end with a
>> 20A Gould TRM20 inline fuse. According to the literature, they have a
>> 200% rating time delay of 12 seconds.
>> That seems appropriate as the wire should only see the max output of
>> the charger TO the batteries, 20A. If the charger fails and somehow
>> creates a dead short, the 20A fuse will eventually open under the
>> massive current flowing FROM the batteries.Hopefully before the fire
>> starts.
>>
>> I assume your installation of the MRBF (Marine Rated Battery Fuse)
>> Terminal Fuse is to provide circuit protection for the entire DC
>> system, not just the battery. I am planning to do the same as this
>> seems to be a weakness in our installations as well as most boats.
>> Since you are protecting the entire DC side from excessive current
>> flow, you will need to estimate the max DC load coming from the
>> batteries under normal conditions (is it at starting?) and figure out
>> how long that load will exist (ie. can I use a fuse with some
>> time-delay characteristics?).
>> I looked at this some time ago and concluded that I would need a 150A
>> fuse to avoid tripping with the starting current on top of the other
>> loads at the time of starting. Anyone else looked into this and have a
>> different answer?
>>
>> Karl
>>
>> On Sun, Aug 12, 2012 at 1:25 PM, JJ Morrison <sail-ability at sympatico.ca> wrote:
>>>
>>> I have used 4AWG on my Zantrex True Charge 2 and at 40amp I fused it to 50amp which is what the Zantrex folks advise. I also used the MBTF fuses which makes a really neat job; no requirement to cut wire.
>>> Cheers
>>> JohnM
>>>
>>>
>>>
>>>> Date: Sun, 12 Aug 2012 07:10:52 -0400
>>>> From: kmielen at suddenlink.net
>>>> To: C320-List at catalina320.com
>>>> Subject: Re: [C320-list] Battery Charger Wire Size
>>>>
>>>> 4 AWG wire on my 2000 model. Not sure on fuse size... why not 20A if
>>>> that is the max output of your charger?
>>>>
>>>> Karl
>>>>
>>>>
>>>> On Sun, Aug 12, 2012 at 12:01 AM, Dick Walker <dickwalker at att.net> wrote:
>>>>> I suggest you put the start battery on #1 and the two batteries on #2. Easy to remember.
>>>>>
>>>>>
>>>>>
>>>>> Cheers
>>>>>
>>>>> Dick Walker
>>>>>
>>>>>
>>>>> On Aug 11, 2012, at 8:36 PM, "Welch, Myron D" <myron-welch at uiowa.edu> wrote:
>>>>>
>>>>>> I am about to begin installation of a dedicated start battery and parallel my two 4Ds as the house battery.
>>>>>>
>>>>>> I will be changing and installing several new cables and have a question about the wire running from the charger to the house battery. I have a 1995 model with a Xantrex 20 amp charger mounted on the forward bulkhead of the port locker. It has a #10 wires to the battery which I believe is considerably undersized. I believe Catalina changed this wire size on later models. For those of you with newer boats, what size wire is used?
>>>>>>
>>>>>> Also, there were no fuses from the charger to the battery. I have now added MRBF fuses. What size fuse should I use?
>>>>>>
>>>>>> Thanks for your help.
>>>>>>
>>>>>> Myron Welch
>>>>>> Wind Instrument, #238
>>>>>> Iowa City, Iowa
>>>>>> Edward C. Grace Memorial Harbor
>>>>>> Elk Rapids, Michigan
>>>>>>
>>>>>> Sent from my iPad
>>>>>>
>>>