[C320-list] Inadequate Dedicated Starting Battery

[Jack Brennan]

Hi Troy:

I’m not an engineer, so I have to qo with what has worked for me. It may be that I have been blessed with two great Yanmars that start in a split second, no cranking, and run all day. The starting load on my batteries is as minimal as can be.

My system is that I have three group 24s as house on No. 2 and one group 24 on No. 1 as reserve. I have 300 watts of solar and a Xantrex solar controller that charges each bank independently. I use No. 2 almost exclusively, so No. 1 just sits there completely charged and happy.

In sunny Florida, solar usually tops off the batteries by early afternoon. In a recent anchor out, my wife draped so many Christmas lights on the boat that we were at 11.7 volts when we went to sleep. We were at 12.2 by 10 a.m. 

I could be wrong because I’m not at the boat, but I’m pretty sure the cable to the starter (and between the charger/controller and the batteries) are all 0. I want to say the two cables between the batteries and the switch are maybe 2. And yes, the windlass is 4.

Yeah, my windlass cables are connected to No. 1, but I almost never use the windlass because it is the original model with no chain gypsy. Even though I’m pushing 69, I can still do a good job as a human windlass with a 35-pound Delta and 40 feet of chain, especially because most of my anchoring is in 8-10 feet of water.

I still wish I could get Trojans into that starboard settee locker, but I can’t see any way to do it without jury-rigging the setup. Inches count. I bought some Korean golf cart batteries that fit, but they died after two years. One was so hot I was lucky it didn’t explode. That cured me of Rocket batteries.

Jack Brennan
Sonas, 1998 Catalia 320
Tierra Verde, Fl.
Dolphin Cruising Club of Tampa Bay



Sent from Mail for Windows

From: Troy Dunn
Sent: Tuesday, December 7, 2021 8:35 PM
To: C320-List at catalina320.com
Subject: Re: [C320-list] Inadequate Dedicated Starting Battery

Couple of nagging issues here.    The original 4AWG cables were for the
charger and windlass.   You can look in my gallery for the original DC
wiring diagram as well as a decent idea of a good way to set up for your
current configuration.   Trying to start your Yanmar engine with a 4AWG
cable and by who knows what path is robbing your starter of power due to
voltage drop/sag.    Even when you are successfully cranking you aren’t
doing it well and that will lead to premature starter failure as well as
battery issues.   Upgrade to 1/0 cable which is really required for the
amps your starter is drawing.

Also if you are using this battery as a dedicated start battery then most
CCAs is the best way to go for deciding which battery to get.
Unfortunately it sounds like maybe your battery is wired through the
combine switch as a reserve battery not a start battery.   Sounds like
semantics but it isn’t.   If you have the normal 1/2/BOTH/OFF switch then
you are most likely just having your G27 battery hanging out in what you
think is full reserve use for your starter…but….your windless might (I say
might because you really need to understand why there are 4AWG cables on
the battery) still be wired to the G27.   That would mean that your G27 is
getting used every time you use that current sucking device at the bow of
your boat.   Now…if for instance you anchor all week, you think the battery
is hanging out…all the while you are actually hitting hard for juice coming
off anchor…then…you have a big problem if you aren’t a)switching to BOTH
while using your alternator or b) have an ACR.

Number 1 is a no brainer your starter can draw huge currents…especially
when it’s hard starting (the current goes up actually)   Your wire needs to
be sized to that current draw and 4AWG isn’t correct.

Number 2 is way more complicated with so many variables…you need more info,
maybe you are fine or could be fine with simple “operational work arounds”
(this is engineer lingo for we messed up the design because we didn’t
understand the requirements so…don’t do that…LOL)

FWIW

Troy Dunn
Hull #514 (Wonky Dog)