[C320-list] Battery Charger Wire Size

[Karl Mielenhausen]

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
>> >>
>