[C320-list] Golf Cart Batteries in Boats

Wed Oct 24 08:39:52 PDT 2007

Hi Bob,

The group has discussed this before, and remains somewhat divided, but the
main reason they aren't offered, is battery and charging experts tend to
agree that they really don't offer a capacity advantage in 12v applications
over their rated life.  

I've offered technical articles written by battery / charging engineers that
explain why.  I've not yet seen an electrical engineering article that shows
that GCs in the series/parallel configuration we're talking about being able
to supply more usable power than parallel 12v batts.  I've seen lots of
anecdotal articles that say it's a good idea, but fail to mention the
practical things that mitigate the theoretical advantage.

If someone can locate a battery mfg that would recommend using *their* 6V GC
batteries in series/parallel config over *their* 12v parallel deep cycle
batteries as a way to provide extra capacity, please pass along the name and
we'll get to the bottom of this.  So far Exide and the Rolls guys have said,
for a fixed given cubic volume,  use paralleled 12v batts in a 12v
application, and paralleled 6v in 6v applications for best results.

Why?

1) GCs double the number of terminal connection points. These reduce the
voltage available at load and reduce the usable AH.  Over time this gets
worse as terminals tarnish at the connection points.  If you clean your
battery terminals and posts regularly and have super high quality sealed
cables, this helps mitigate the connection losses.

2) Unless all 4 GC batteries are exactly the same age and # cycles, and
equalized to be nearly identical, each series pair of GC batteries is always
limited to the available power of the weaker one. The weaker one will fail
faster as well.  The 6 cells in a 4D deep cycle battery have a much higher
likelihood of being matched and are more easily equalized because they were
all mfg at the same time with the same materials.  Not so with GC batteries.
There is no requirement that paralleled batteries be that closely matched.

3) GC batteries are great in parallel for 6V applications, but in
series/parallel (12v) they suffer much more from mismatch than parallel 12v
batts.

4) It's a myth that you can just replace on battery if it fails.  Doing that
does you no favors in the capacity or reliability department, which is what
this whole discussion is about.

5) It's easier to find a 12v replacement battery in a pinch than it is to
find a 6V GC battery.

Now, I know some will swear that you've done this with spectacular results,
but I doubt you've run the controlled tests to see what your true amp hour
results are.  If so, feel free to publish the results and how they were
measured.

You can pretty much disregard the AH ratings as a way of comparing a 6V
battery (X) with a 12V battery (Y) unless you know for a fact that both
batteries were tested using the same load current and discharge percentages.

-Jeff

-----Original Message-----
From: c320-list-bounces at catalina320.com
[mailto:c320-list-bounces at catalina320.com] On Behalf Of Robert E. Sloat
Sent: Wednesday, October 24, 2007 10:38 AM
To: C320-List
Subject: [C320-list] Golf Cart Batteries in Boats

John and Karl-I am curious why sailboat manufacturers don't offer golf cart 
batteries as stock items on their new boats?  I have yet to see them even 
offered as an option on a new sailboat.

Bob Sloat
Savannah 894
----- Original Message ----- 
From: "John Frost" <john at frostnet.net>
To: "'C320-List'" <c320-list at catalina320.com>
Sent: Wednesday, October 24, 2007 6:40 AM
Subject: Re: [C320-list] FW: Re: Xantrex charger - battery bank 
setupwithstartbattery

> Thanks Karl. I just got to look at the photos this morning and they really
> helped. I'm on my way to St Louis this morning to see my new boat in 
> person
> and meet with the installer of all my new "toys". His banker will soon 
> love
> me.
>
> Best Regards,
> John Frost
>
>
> -----Original Message-----
> From: c320-list-bounces at catalina320.com
> [mailto:c320-list-bounces at catalina320.com] On Behalf Of Karl Mielenhausen
> _/)
> Sent: Friday, October 19, 2007 8:49 AM
> To: C320-List at catalina320.com
> Subject: [C320-list] FW: Re: Xantrex charger - battery bank setup
> withstartbattery
>
>
> John,
>
> Congrats on the purchase of a new C320!!!
>
> I added a Walmart Maxx 1N battery as a starter, just forward of where my
> 4D's were. About the same time, I converted the 4D's to golf car batteries
> (you will probably do that when your 4D's die in 4-5 years).
>
> The stock 4D's are a combination battery, not designed for true deep 
> cycle,
> like golf car batteries are.
>
> I took the easy wiring solution and utilized the existing "1-2-Both" 
> battery
> switch. I put the starter battery on #2 and the house bank (all 4 golf car
> batteries) on #1. My Xantrex charger has 2 legs, so one goes to the 
> starter
> battery and the other to the house bank. All batteries need to be the same
> type (ie. lead acid, AGM, etc) for this to work but the charger seems to 
> do
> a good job of dividing its output to charge the bank that needs it the 
> most,
> which is in my case, always the house bank. In fact, I leave the battery
> selector on #1 for engine starting and alternator charging, and hold the
> starting battery in reserve IF the house bank will not start the engine.
>
> One option you might consider, especially if you plan on a lot of cruising
> and anchoring out, would be a better alternator/regulator. My stock 
> Hitachi
> 55 amp with its internal regulator is pretty anemic when it comes to
> "refilling" the 440 AH house bank. I'm sure I get a decent output for only

> a
> few minutes and then it drops down to avoid overcharging. A smart, 3-stage
> external regulator coupled with a 100 A alternator would be much better. 
> Or
> you could buy a portable Honda generator and run the 120VAC onboard 
> battery
> charger when you get to anchor!!!
>
> Dig around the Photo Gallery for more ideas....
>
> http://www.catalina320.com/gallery/album86
>
> http://www.catalina320.com/gallery/6-Volt-Batteries-and-Solar-Panel
>
> http://www.catalina320.com/gallery/album72
>
> http://www.catalina320.com/gallery/StartingBattShelf
>
> http://www.catalina320.com/gallery/album31
>
>
>
> Karl Mielenhausen
>
> 2000 C320 Hull#690 "Silver Lining"
>
> New Bern, NC
>
> http://pages.suddenlink.net/kmielen/
>
> From: John Frost [mailto: john at frostnet.net]
>
> To: c320-list at catalina320.com
>
> Date: Wed, 17 Oct 2007 08:58:39 -0500
>
> Subject: Re: [C320-list] Xantrex charger - battery bank setup with
> startbattery
>
>
>
> I would like to add a starting battery to my new 320. Where have you
> folksfound to be a good place for a third battery and what size and
> switching didyou use?Best Regards,John Frost(256) 650-0335 -----Original
> Message-----From:
>
c320-list-bounces at catalina320.com[mailto:c320-list-bounces at catalina320.com]
> On Behalf Of amshd2 at aol.comSent: Tuesday, October 16, 2007 9:55 AMTo:
> c320-list at catalina320.comSubject: Re: [C320-list] Xantrex charger - 
> battery
> bank setup withstartbatteryPhilI have the set up you described with a
> Xantrex Freedom 20 and 27 group startbattery and 2 4Ds. The 4Ds are wired
> together and charge together.? It worksgreat. I also have a
> keyed?isolator/Eng kill ?switch for the?start battery.?When at anchor or
> sailing I?turn it off.?This way I do not draw from thestart battery except
> for starting.??The switch?helps in case a guest does something to run
> the?batteries?downover night.?I run the refer 24/7 as long as the ?boat is
> in the?water.? I run the referon the hook
> but do turn it do to around 2 or 3 and take along some ice.?Will motoring 
> I
> turn it back up all the way. Tony  -----Original Message-----From:
> sholdr at aol.comTo: c320-list at catalina320.comSent: Tue, 16 Oct 2007 10:44
> amSubject: [C320-list] Xantrex charger - battery bank setup with start
> batteryAm changing to Xantrex charger and replacing my 2? 4D house 
> batteries
> andadding a start battery -- It seems since the Xantrex has 3 channels it
> would bebest to charge each battery separately but combine the house
> batteries (Position 2)?(automatically if possible) when in use keeping the
> start battery separate(Position 1) except in an emergency (Both).? We are 
> on
> a lake,overnight occasionally, no A/C, when at dock run the Refer on shore
> power.? Is it possible/necessary/preferable to separately charge the 2 
> house
> batteries oris this more trouble than it's worth?ThanksPhil HansenCamelot
>
#322________________________________________________________________________
> Email and AIM finally
> together. You've gotta check out free AOL Mail! -
>
http://mail.aol.com_________________________________________________________
> _______________Email and AIM finally together. You've gotta check out free
> AOL Mail! -http://mail.aol.com
>
> _______________________________________________
>
>
>
>
> 