Batteries and the fridge

[PLKennedy]

A friend of mine, and a member of the Association, told me that it was OK for me to run the refridgeration for 24 hours on one battery so long as I charged the battery for one hour the next day.  I tried it, with one small block of ice in the fridge, and it worked fine.  The battery I used still had 12 volts in it the next day.

Can I rely on this one time test?  I alternate batterirs every day whilst cruising and use both when running the engine.

Peter

[c34member]

One hour on a 51A alternator seems like a short time to get the battery back after a 24 hr drain from the refrigerator.  I don't have the statistics, but if you keep up a good RPM for that hour it is probably sufficient.  I cheat and have a charge condition monitor on my inverter panel, so I just motor until the house bank is "in the green".

[c34member]

I have a third (isolated) starting battery as Ron mentions.  The alternator is connected directly to that battery.  I then have a "Both-2-1-Off" switch on the starting battery (starting battery connected to the "1" terminal and the house bank to the "2" terminal).  I have an identical switch on the house bank.  So . . . I always have a load on the alternator when the engine is running regardless of the switches (important), I have an inside engine switch that deactivates the pedistal starting switch, I can use the house bank to start the engine, I can isolate the starting battery when on extended cruising, and I can switch between the two 4D house batteries so I have a house reserve.  I only have to remember to switch both switches to "Both" when running the engine.  In my future plans I want to add two solenoids that energize off the oil pressure sensor circuit to automatically trip the batteries into the charge loop whenever the engine is running (a friend has this set-up on his C-36 and it works as slick as can be).

PS - my inverter is connected to house battery #2; but again I must remember to switch the house bank to "Both" when using the shore-power charger to recharge both house batteries.  Checking the switches before switching on/off breakers at the panel is just a habit I have gotten used to.

[PAUL T.]

PETER.... I use a honda 2000 watt portable generator when I cruise. It works great!!! It gives me hot water in 20 minutes and it runs my battery charger. you can also use 110 outlets like your on shore power. The generator automaticaly regulates rpm according to demand.
It only weighs 46 pounds and is so quiet you can't hear it when down below. you never have to run your engine!!!  Just a thought....PAUL

[SteveLyle]

Legend (and the Tech Notes) has it that the fridge draws 5 amps with a duty cycle of 50% - so 5*24*.5 = 60 amps/day.  An hour a day of engine time is going to be a little short, unless you have a high output alternator.

[PLKennedy]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by PAUL T.:
PETER.... I use a honda 2000 watt portable generator when I cruise. It works great!!! It gives me hot water in 20 minutes and it runs my battery charger. you can also use 110 outlets like your on shore power. The generator automaticaly regulates rpm according to demand.
It only weighs 46 pounds and is so quiet you can't hear it when down below. you never have to run your engine!!!  Just a thought....PAUL<HR></BLOCKQUOTE>

Where do you keep the gererator?

Peter

[Stu Jackson]

Peter, Your initial comment was a lesson in the steadily diminishing law of returns.  If it worked fine, how did you know?  Do you have a Link 10 to measure amps in and out?  If not, you could eventually run your battery bank flat, even though it looked good for the first few days.  Have you done an energy budget?

If you don't have an external regulator with a newer alternator, your 55 amp alternator is still the OEM internally regulated, which is doing relatively little to recharge your batteries.

Steve Lyle is right about the drain from the fridge.

Try checking out the Ample Power website (www.amplepower.com), they have a great Primer that explains a lot about batteries.

It also appears that you are simply switching between your two batteries daily in lieu of having a separate dedicated starting battery.  You might want to consider a separate starting battery and then wire your two existing batteries together for a larger, more efficient house bank.

Just some thoughts,

Stu

[PAUL T.]

Peter.... In response to your question, where do I keep the generator?  When I'm sailing I keep it under the dinett table behind the mast, no fuel in it of course. When in use I put it on deck directly in front of the mast, I find this spot gives me no vibration down below. I keep the gasoline in a safety can secured on deck. I would also like to add that having the generator is a great saftey net because you always have the ability to start your engine. Also be aware of where the exaust is going always have good ventilation. Carbon monoxide poisoning has been in the news a lot lately. BE AWARE!!!!  PAUL "SEAESTA"

[Stu Jackson]

Peter

Further to my post from yesterday, I've been meaning to post this for some time now, and this seems an appropriate place to do so.


IS IT BETTER TO HAVE ONE OR TWO BATTERY BANKS FOR HOUSE USE?
(By Nigel Calder - I DIDN’T write this!!!)  ["Calder and Calder" for searching]

The popular arrangement of having two house banks alternated in use needs scrutiny
before I go any further.

LIFE CYCLES: As we have seen, the life expectancy of a battery in cycling service is
directly related to the depth to which it is discharged at each cycle - the greater the
depth of discharge, the shorter the battery’s life.

This relationship between depth of discharge and battery life is NOT linear.  As the
depth of discharge increases, a battery’s life expectancy is disproportionately
shortened.  A given battery may cycle through 10% of its capacity 2,000 times, 50% of
its capacity 300 times and 100% of its capacity around 100 times.

Let’s say, for arguments sake, that a boat has two 200-ah battery banks, alternated
from day to day, with a daily load of 80 Ah.  Each bank will be discharged by 40% (80
Ah of one of the two 200 Ah banks) of its capacity before being recharged.  The
batteries will fail after 380 cycles, which is 760 days (since each is used every other
day).  If the two banks had been wired in parallel, to make a single 400 Ah battery bank,
this bank would have been discharged by 20% of capacity every day, with a life
expectancy of 800 days, a 5% increase in life expectancy using exactly the same
batteries!

But now let’s double the capacity of the batteries, so that the boat has either two 400
Ah banks, or a single 800 Ah bank, but with the same 80 Ah daily load.  The two
separate banks will be cycling through 20% of capacity every other day, resulting in a
total life expectancy of 1,600 days.  Doubling the size of the battery banks in relation to
the load has produced a 210% increase in life expectancy.  The single 800 Ah bank will
be cycling through 10% of capacity every day, resulting in a life expectancy of 2,000
days - a 25% increase in life expectancy over the two (400 Ah) banks, and a 250%
increase in life expectancy over the single 400 Ah battery bank!

There are two immediate conclusions to be drawn from these figures:
1.  For a given total battery capacity, wiring the (house) batteries into a single high
capacity bank, rather than having them divided into two alternating banks, will result in a
longer overall life expectancy for the batteries.
2.  All other things being equal, any increase in the overall capacity of a battery bank
will produce a disproportionate increase in its life expectancy (through reducing the
depth of discharge at each cycle).

FOR BATTERY LONGEVITY, A SINGLE LARGE (HOUSE) BANK, THE LARGER THE
BETTER, IS PREFERABLE TO DIVIDED (HOUSE) BANKS.

[dave davis]

THANKS STU FOR REMINDING ME ABOUT THAT GREAT BATTERY INFO FROM CALDER. I HAVE A QUESTION, SHOULD I JUST LEAVE THE MASTER SWICH ON "ALL" SO THAT IT WILL COMBINE MY TWO BANKS OF 220 AH EACH? I DO NOT HAVE A STARTER BANK.
THANKS , DAVE :)

[Stu Jackson]

Dave

My DEFINITIVE answer has to be: "It Depends!"

You could add a separate starting battery and then combine your four golf carts into one big house bank.  But I'm guessing you don't want the weight.  

To assure you always have a "backup" for starting the engine, I'd continue to use each separate bank.  With 220 ah in each bank as you now have it wired, that would be enough to keep you running for a day or two even at anchor.

I'd advise again using ALL because you wouldn't have a backup for starting in case the load you imposed (or some other glitch) used up your bank's capacity (either or both).

Stu

PS - the main purpose of me posting the Calder info was to advise folks who use separate battery banks for different house loads (i.e., separate "dedicated" fridge battery, then another for the lights, stereo, etc., that that just doesn't make too much sense.  It doesn't really address the issue of a "two house bank" setup, switching off daily, but does indirectly.  Seems the best bet is as big a house bank as you can get, with a separate starting battery.

[Stu Jackson]

Ample Power Source

I forget (more often than not, these days!) if I ever posted this source for the Ample Power Primer.

http://www.amplepower.com/

While at first glance it may seem "self serving" when read, they did kind of write part of the book on electrical systems.

When read with Calder, West Marine's Advisors, and other reputable sources, it begins to make sense.

The basic concept is that there are many options in designing electrical systems for boats, and there is no ONE right answer.  

Combiners or Echo Chargers or the 1-2-B switch?

Separate inverters and chargers or combination units?

How you plan to use your boat (dockside, day sails, single or few overnights, extended times being "unplugged?"  (Energy budget, sizing and size of house banks, alternator size, etc.)

If you figure out HOW you plan to use your boat FIRST, you can design and install and USE what's right for YOU.

Have fun.
Stu

[Mike Vaccaro]

Agree with Ron!  The bottom line is that you've got to have some idea how many electrons you need, and how quickly you use them.  Can't beat a monitor for simplicity or accuracy; but you can use a watch as well.  Unfortunately, this requires that a) you know your amp/watt draw of various electrical components, and b) you do math--but it will work.  

There are countless ways to set up an electrical system.  Here's what we did--our goal has been to make our system as simple and redundant as possible.  We have one house bank (approximately 450 amp hours) made up of four golf cart batteries.  It is either ON or OFF.  It is charged via a 115v 3-stage charger.  This charger is powered by either shore power or a 5KW "Seapower" alternater mounted on the front of our engine.  It is not recharged by the standard engine driven alternator.  We have a separate starting battery for the engine.  It has no ON/OFF switch and is recharged by the engine-driven alternator.  Additionally, this battery has a separate 3-stage 115v charger that operates off of shorepower (not the same charger used to charge the house bank).  This is the same way your car is wired and requires no user interface other than turning the key.  To interconnect the system?  A set of marine jumper cables!  Could use a 1/2/Both switch; but we've got small kids so this way the two systems are never connected and the starting battery can't be accidentally discharged.  

The 5KW Seapower unit has proven to be a pretty good compromise.  It was on the boat when we purchased it, although it was inoperative and required repair.  We couldn't find a clever way to install a separate generator (at least within the family budget!).  But the Seapower unit allows us to have AC power when required (albeit with the main engine running).  It does draw quite a bit of horse-power, several ponies per KW but the only system on-board that has proven to be a large draw is the air conditioner.  We don't engage the Seapower when the engine is critical, e.g., docking, challenging weather, and avoid use of the air conditioner unless it's a really hot, windless day and we're cruising on the motor.  We will engage during general motoring if the engine is going to run for a half-hour or so to continue to charge the house bank.  We've found that less than an hour per day is sufficient to keep the house bank topped off (we have a NORCOLD refrigeraton system).

Incidentlly, we've always been very happy with Catalina--don't think that you can beat the value and our new (to us!) 34 is the second Catalina we've owned; but I've been less than impressed by the electrical system.  The factory system is less than stellar, and the two previous owners did multiple modifications, some of which not only weren't up to code, but weren't safe.  If you're not comfortable with doing electrical work, you might consider hiring a qualified marine electritian to at least find/correct potentially dangerous faults.  If you're purchasing a new boat, a critical look at the electrical system by the surveyor is definitely warranted!

Best of Luck!

Mike Vaccaro
"Spirit" '88 Hull 563

[Stu Jackson]

New Boat Electrical

Mike wrote:  "If you're purchasing a new boat, a critical look at the electrical system by the surveyor is definitely warranted!"

If you are purchasing a new boat, you'll find two major flaws that have never been addressed by Catalina (or, for that matter, by many other "stock" boat manufacturers):

1.  Standard stock alternator with no external regulation - see discussions above about inadequate engine charging without external regulation.

2.  Poor to useless Charles chargers installed by Catalina.  They are, as far as we can tell, not true three stage chargers.  Do a message board search for "Charles Redux" and you'll find the postings.

Is this bad?

Not necessarily, since this thread has mentioned that people use their boats in many different ways.

It is difficult to understand why Catalina chooses not to provide enhanced electrical systems as an option, which many have suggested to the factory over the years.

My guesses are that, 1) it complicates the production; 2) most people buying new boats don't examine the electrical systems; 3) there hasn't been enough feedback or push for enhancements; 4) people like - or learn to do or have done - the extra electrical work necessary to make their boats work for them.

Many many years of complaints about bad batteries are basically a SYSTEM problem - too small a bank with too big a load, inadequate alternator charging, horrible (at best) factory shorepower chargers - but we've all heard it before.

One of the good things is that it forces us to learn more about our boats, and design and install what works for us individually.

There are so many more reference sources on electrical systems than ever before, so even if you're not an electrical "geek" you can begin to learn about it.  Another good source in addition to Calder and Ample is Jack Rabbit Marine, who, I realized just yesterday, offer Ample alternators.  These alternators look just like the old Motorolas, so if you are thinking of upgrading your alternator, you won't have to shave your existing bracket to use a Balmar.

[8/29/13 - Stu - Jack Rabbitt went out of business.  Try the "Electrical 101" topic in the "101 Topics" sticky.]

Really, there are so many options, maybe the factory made the right choice after all - customers get to customize!

[Stu Jackson]

In responding to a question, off line, from a C27 owner, I noted to her what I had written in the Nov. 2006 Mainsheet Alternator/Regulator Upgrade article:

Alternator Output:  The older boats with only one 1-2-B switches are usually factory wired with the alternator output to the "C" post of the switch.  This means that the switch was actually used for two purposes: (1) which battery bank(s) the alternator charge goes to when the engine is running; (2) which bank is chosen for use for DC power.   We changed that.  We moved the original alternator output FROM the "C" TO the "1" post (our house bank) of the switch.  The Combiner charges the start bank without having to use the 1-2-B switch for selecting alternator charging output ONLY because we moved that connection.  The revised alternator charging path was from the alternator through the AutoMac to the "1" switch post to the house bank, using the #4 OEM red wiring.   IMPORTANT NOTE: You cannot simply move the alternator output from the "C" to the "1" post without a Combiner or Echo Charger type relay equipment because the start bank would not get charged.  Another way to put this is: If your alternator output is wired to the C post of the 1-2-B switch, and you do not have a combiner (or equivalent), then you have to start the engine with the switch on B (ALL) because this would be the only way to charge both of your banks from the alternator.

The point being:  SINCE most boats are wired FROM the alternator TO the 1-2-B switch, MOVE the alternator output TO the house bank, and figure out how YOU would like to have the switching done to keep your start bank charged from WHATEVER sources you choose.

Interestingly, not much has changed since this thread from four years ago.