[C320-list] New House Batteries

Sun Dec 4 17:21:06 PST 2016

Huh? Wad he say?? I told ya so, I think. 
Kidding aside, sounds good to me. But, then, sounds like what Jeff Hare said, too. 
I think I'll switch to Eveready "D" cells, and just throw them away each day.

Warren and Pattie Updike
1994 C320 "Warr de Mar" #62
Middle River, Chesapeake Bay

-----Original Message-----
From: Scott Thompson [mailto:surprise at thompson87.com] 
Sent: Saturday, December 03, 2016 6:41 PM
To: C320-List at Catalina320.com
Subject: Re: [C320-list] New House Batteries

   I've been mulling this over a bit more. The math for the "wrong" two
   parallel battery arrangement seems pretty straightforward. The voltage
   difference between the two interconnection points cannot depend on the
   particular loop or circuit in which it is measured. If the two
   batteries are connected at the terminals of battery 1 and if the
   external loads are connected at the same points, then applying Ohm's
   law we must have I*R be the same for the flow through each battery
   circuit connecting these two points, and so the ratio of the current
   flowing through battery 1 to that flowing through battery 2 is R2/R1
   where R1 and R2 are the total equivalent resistance of each circuit. If
   the batteries are identical and have internal resistance r and if the
   total resistance of the two short connecting cables is c then R1=r and
   R2=r+c. Thus the ratio of the current flowing through battery 1 to that
   flowing through battery 2 should be (r+c)/r = 1+(c/r). If the
   connecting cables were ideal, with zero resistance (c=0), then this
   ratio is 1, which is the case I had in mind in making my initial post
   on this topic. On the other hand, if the batteries are big so that r is
   small, then even a small cable resistance can make the ratio deviate
   significantly from 1.
   I don't know what the right values are for r and c for a typical 320
   installation, but in the SmartGauge example at
   [1]http://www.smartgauge.co.uk/batt_con.html, c=2*.0015=.003 and r=.02,
   in which case the ratio is 1+.003/.02 = 1.15. That is, battery 1 will
   deliver 15% more current than battery 2 under load, at least initially
   when both batteries are fully charged. This ratio is independent of the
   total  load, so even under modest house bank loads there could be an
   uneven draw.
   My understanding is that the internal resistance of a battery increases
   as it it discharged. Thus over time the relative load taken by battery
   1 should fall due to its greater rate of discharge.
   I think the takeaway is that if your batteries are connected in this
   fashion then you want to use heavy duty connecting cables with good
   connections at each end to parallel the batteries, which probably is
   good advice even if using the "best practices" wiring method.
   Scott
   p.s. After writing the above I calculated the ratio of current for
   battery 1 to that of battery 2 in the SmartGauge 4 battery example and
   found that it was far greater at about 1.37. I believe the difference
   is caused by the fact that the first set of link cables needs to also
   carry all of the current for batteries 3 and 4 in that example, which
   means a more significant voltage drop across those short cables. In
   short, the problem is much worse for the 4 battery example than for the
   two battery house bank arrangement in most 320s. It's not just that
   there are more links involved in the battery 3 and battery 4
   connections, but also that the battery 2 connections need to carry a
   larger current than in the two battery case.

   On 12/1/2016 10:05 PM, Jeff Hare wrote:

Hi Warren,

Sorry, not *quite* buying that explanation.  :) :)  I totally get the theory beh
ind it. But the reality is that it doesn't matter IN THIS APPLICATION.

Drawing from a parallel bank "diagonally"  (ie: 2 parallel batteries with Positi
ve coming off of battery 1 and Negative coming off of battery 2) might have some
 utility for constant high current situations with undersized cables and a lot o
f individual batteries, but we are only paralleling 2 batteries with suitably la
rge cables on really short runs, so this really isn't a factor.

In a large Solar array with 10 or 20 batteries, this is a reasonable wiring choi
ce because of the additive resistance effect of the connectors and the high curr
ents driving inverters.  Think about a dozen batteries in parallel, lined up sid
e by side (all + to + and - to -).  Here it totally makes sense in order to even
 out that resistance because connecting + and - to the first battery means you c
ould have 10 feet of cable and dozens of connectors to pass through before you g
et to the last battery.  But even then you'll still have some batteries pulling
more than their share just because of slight differences in battery chemistry.

2 Batteries in Parallel with properly sized wires and decent connections will dr
aw from each battery proportionally to their capacity and internal resistance.
With the load drawing from the terminals of the first battery will not degrade t
he first battery more than the second over time. If one of your batteries died i
n 4 or 5 years it didn't die because of where you connected the load.

My batteries will be 10 this spring.  They have been hard wired in parallel sinc
e they were installed.  The load point was entirely from the aft most battery pl
ates (until last spring when I did some rewiring after the lightning strike).  T
his is anecdotal but if the theory we're discussing is true, I should have one w
eak or dead battery and one good one.  Just not the case.

If you have crappy connections, you'll place a larger load on the battery with t
he best quality electrical connection regardless of where you tap into the bank.
  It's just Ohms law.  That will lead to one battery playing the front person on
 a bicycle built for 2.

For typical house loads, there should be a pretty insignificant difference in lo
ading between the batteries because of connector resistance.  There are other ch
emistry factors that will probably combine to play a bigger role (always assumin
g you have decent connections).

Even if both batteries were installed new at the same time from the same source,
 they will not be identical.  They'll charge slightly differently and have sligh
tly different internal resistances and overall capacities and they'll contribute
 differently.

My suggestion is keep your connections clean and don't sweat a few milliamps.  T
he Theory is one of precision but unless you consider *all* the factors, you're
only fooling yourself.

That said, you should always go with whatever logic makes you most comfortable.
 :)  It's what sailors do!  :)

Cheers!
-Jeff Hare

-----Original Message-----
From: C320-list [[2]mailto:c320-list-bounces at lists.catalina320.com] On Behalf Of
 Warren Updike
Sent: Thursday, December 1, 2016 4:10 PM
To: [3]C320-List at Catalina320.com
Subject: Re: [C320-list] New House Batteries

I can't find the source of the information; but, here is my understanding. Think
 of it like flows of water. In a parallel connection, if you have the load pos a
nd neg on the same battery #1, then the flow of least resistance is in and out o
f the same battery #1. As the charge degrades on that battery, makeup current fl
ows from the connections with the other battery #2, to balance the charge across
 both batteries. This is different than connecting the pos load to battery #1, a
nd the neg load to battery #2, which causes the load to flow smoothly through al
l 12 cells.

The difference between the two banks seems trivial; but, according to what I rea
d, from a reliable source I can't remember, the first example results in a great
er load on the cells in battery #1, causing that battery to degrade sooner. We c
ertainly don't want that.

I welcome any challenges or support for this theory.

Warren and Pattie Updike
1994 C320 "Warr de Mar" #62
Middle River, Chesapeake Bay

-----Original Message-----
From: Scott Thompson [[4]mailto:surprise at thompson87.com]
Sent: Thursday, December 01, 2016 6:47 AM
To: [5]C320-List at Catalina320.com
Subject: Re: [C320-list] New House Batteries

Warren, the logic of that escapes me. If the batteries are connected in parallel
 then the positive terminals are tied together as are the negative terminals. As
suming the cables and connections are all good, it shouldn't matter which of the
 tied terminals also has the connection to loads or charge source.

Scott Thompson

On 11/30/2016 5:07 PM, Warren Updike wrote:

Jim, re fact that one batt goes first, here is a thought. If they are connected
in parallel, the pos and neg cables should be attached to different batteries. T
his forces the load to pass through all 12 cells. If you have the original wirin
g with each battery separate, forget I said this.
Warren

-----Original Message-----
From: [6]jbrown5093 at yahoo.com [[7]mailto:jbrown5093 at yahoo.com]
Sent: Tuesday, November 29, 2016 8:35 AM
To: [8]C320-List at Catalina320.com
Subject: Re: [C320-list] New House Batteries

Just replaced my second set of flooded 4Ds after 6 years. Interestingly it was b
attery 2 after 6 years on both sets that went first. I was happy with the floode
d cells but the local boat yard (getting to old to muscle this set out) said tha
t flooded cells are no longer considered acceptable by ABYC standards if they ar
e housed in the salon or berths without separate ventilation-probably because of
 potential problems like Greg's. if true that might be a consideration if you ne
ed a survey for insurance or sale purposes in the next few years.

On their recommendation I went to AGM Lifeline batteries. I had the Charles char
ger that did not support AGMs. Called Charles and they will convert the charger
to AGM compatable for $75.  Great people to work with-much like Garhauer.

Jim Brown
Desafinado 973

Sent from my iPad

On Nov 29, 2016, at 5:42 AM, Scott Westwood [9]<scottwestwood at bellsouth.net> wro
te:

  John,
Do you have any pics on where you mounted your solar equip?  That may be our nex
t large purchase.
Thanks,
Scott Westwood [10]scottwestwood at bellsouth.net H (919)-362-8538    C (919)-618-7
185

      From: John Morrison [11]<sail-ability at sympatico.ca>
To: [12]"C320-List at Catalina320.com" [13]<C320-List at Catalina320.com>
Sent: Monday, November 28, 2016 8:45 PM
Subject: Re: [C320-list] New House Batteries

Conventional wisdom of this group has been recommending the deep cycle Interstat
e battery. I purchased 2 several years ago and they R performing well.  My boat
has a 55amp alternator and rather than upgrade it I installed a 185W solar panel
. I highly recommend this upgrade haven't plugged into shore pwr in 2 seasons.
JohnM 1999#574

Sent from my iPhone

On Nov 28, 2016, at 8:32 PM, Dean Agee [14]<dagee at iserv.net> wrote:

Our recently purchased 2002 - 320 came with 4 � year old batteries
which I discovered to be 4D PowerSource Industrial/Tractor Batteries.

A recent overnight trip convinced me that they are heading towards
the end of their life.  Identical replacement batteries are $164
each.  The Marine equivalents run around $600-$700.

Does anyone have thoughts on battery replacement?  I don't mind
spending the extra money - but would like to know what I'm getting for the money
.

Also, in another post, the owner of an early series boat - in the
#160s - said that the Catalina supplied alternator was "undersized".
Does anyone know if Catalina upgrade the alternator in later boats?

Thanks!

Dean Agee

AhSeaHola #912

References

   1. http://www.smartgauge.co.uk/batt_con.html
   2. mailto:c320-list-bounces at lists.catalina320.com
   3. mailto:C320-List at Catalina320.com
   4. mailto:surprise at thompson87.com
   5. mailto:C320-List at Catalina320.com
   6. mailto:jbrown5093 at yahoo.com
   7. mailto:jbrown5093 at yahoo.com
   8. mailto:C320-List at Catalina320.com
   9. mailto:scottwestwood at bellsouth.net
  10. mailto:scottwestwood at bellsouth.net
  11. mailto:sail-ability at sympatico.ca
  12. mailto:C320-List at Catalina320.com
  13. mailto:C320-List at Catalina320.com
  14. mailto:dagee at iserv.net