I am reading a book called "Powerboater's Guide to Electronic Systems".
The book recommends using two dual-purpose batteries if the boat is a
center console. A dual purpose battery is supposed to be good for both
cranking the motor and serving as a house battery. I am wondering why
a dual purpose battery is the best kind for a center console, but not
the best for a cruising boat (he recommended a combination of a
starting battery and a deep cycle battery for a cruising boat). What
are the reasoning behind this? Won't a combination of a starting
battery and a separated deep cycle battery is just as good for a center
console?

My center console is having two dual-purpose batteries just like what
the book has recommended. I guess this is good. I just don't know why
this is good.

Thanks in advance for any info.

Jay Chan

wrote in message
oups.com...
I am reading a book called "Powerboater's Guide to Electronic Systems".
The book recommends using two dual-purpose batteries if the boat is a
center console. A dual purpose battery is supposed to be good for both
cranking the motor and serving as a house battery. I am wondering why
a dual purpose battery is the best kind for a center console, but not
the best for a cruising boat (he recommended a combination of a
starting battery and a deep cycle battery for a cruising boat). What
are the reasoning behind this? Won't a combination of a starting
battery and a separated deep cycle battery is just as good for a center
console?

My center console is having two dual-purpose batteries just like what
the book has recommended. I guess this is good. I just don't know why
this is good.

Thanks in advance for any info.

Jay Chan



I have always used deep cycle for both cranking and house purposes on my
cruisers and runabouts.

Jay,
I am guessing they are recommending two dual purpose batteries for center
console boats because they assume you will not be placing a large demand on
the battery you use for accessories and a dual purpose will meet the lower
amp requirements and still give you good starting. Just make sure you use
your A/B switch so you always have a strong starter battery to crank your
engine.

I can't think of any reason why a marine starter battery and a deep cycle
battery separated with an isolator and A/B switch wouldn't be a good choice
for a center console, especially if you use a aerator for your fish and bait
tank.


wrote in message
oups.com...
I am reading a book called "Powerboater's Guide to Electronic Systems".
The book recommends using two dual-purpose batteries if the boat is a
center console. A dual purpose battery is supposed to be good for both
cranking the motor and serving as a house battery. I am wondering why
a dual purpose battery is the best kind for a center console, but not
the best for a cruising boat (he recommended a combination of a
starting battery and a deep cycle battery for a cruising boat). What
are the reasoning behind this? Won't a combination of a starting
battery and a separated deep cycle battery is just as good for a center
console?

My center console is having two dual-purpose batteries just like what
the book has recommended. I guess this is good. I just don't know why
this is good.

Thanks in advance for any info.

Jay Chan

wrote in message
oups.com...
I am reading a book called "Powerboater's Guide to Electronic Systems".
The book recommends using two dual-purpose batteries if the boat is a
center console. A dual purpose battery is supposed to be good for both
cranking the motor and serving as a house battery. I am wondering why
a dual purpose battery is the best kind for a center console, but not
the best for a cruising boat (he recommended a combination of a
starting battery and a deep cycle battery for a cruising boat). What
are the reasoning behind this? Won't a combination of a starting
battery and a separated deep cycle battery is just as good for a center
console?

My center console is having two dual-purpose batteries just like what
the book has recommended. I guess this is good. I just don't know why
this is good.

Thanks in advance for any info.

Jay Chan


You need a second battery with the capacity to be a starting battery if the
first is dead. Cruising boats, use large deep cycles, that give a low amp
flow for long times. They may not have the short term amp capacity to start
the motor. And deep cycles, are built to not warp the plates when charging.
Starting batteries are not designed to be deeply discharged a lot.

wrote:
I am reading a book called "Powerboater's Guide to Electronic Systems".
The book recommends using two dual-purpose batteries if the boat is a
center console. A dual purpose battery is supposed to be good for both
cranking the motor and serving as a house battery. I am wondering why
a dual purpose battery is the best kind for a center console, but not
the best for a cruising boat (he recommended a combination of a
starting battery and a deep cycle battery for a cruising boat). What
are the reasoning behind this? Won't a combination of a starting
battery and a separated deep cycle battery is just as good for a center
console?

My center console is having two dual-purpose batteries just like what
the book has recommended. I guess this is good. I just don't know why
this is good.

Thanks in advance for any info.

Jay Chan


Sounds like the "Powerboater's Guide to Electronic Systems" wasn't
written by a powerboater.

You've got some bad advice.

There is almost no earthly reason to ever have a "starting battery" on
a boat, except it will help the battery manufacturer sell a greater
number of batteries each year. Starting batteries have lighter weight
(thinner) plates so additional surface area can be exposed to the
electrolyte and maximize the CCA rating in a given case size. Those
thin plates disintegrate faster than the thicker plates in a "deep
cycle" battery, and when one plate is gone the battery is toast. The
thin plates make it bad practice to discharge a starting battery very
deeply- the recharge stresses the thin plates and leads to premature
battery failure.

(I use Rolls batteries on my boat. They are sold with a 10-year
warranty. Rolls doesn't even offer a "starting battery", and the
Rolls/Surette company is one of the premiere manufacturers of flooded
cell batteries.)

If space is so tight that you just can't possibly fit a deep cycle
battery rated for sufficient CCA, then I suppose a "starting" battery
must be used- but that situation will arise once in a couple of hundred
installations. In fact, if space is *that* tight, you battery
compartment is probably inadequately ventilated and you have some
other, potentially more serious problems.

Best plan: Always use a deep cycle battery for house loads. Use a deep
cycle battery with sufficient CCA to start your engine in nearly all
applications. Have at least two batteries, properly cabled and
switched.

Chuck,

I might have been sold a bill of goods (this wouldn't be the first time),
but I was told by boat/us that the Marine Dual Purpose Battery would have
the extra "cranking amps" for a longer period of time, than a Deep Cycle
Battery would provide. I have twin 5.7 gas engines, which require high
cranking amps.

According to this rep. (who seemed to know what he was talking about) , the
Dual Purpose Battery does take more abuse than an exclusive Starting Battery
will, but will not provide the cranking amps for as long of a period as the
Starting Battery or Dual Purpose Battery, (but they do make marine starter
batteries that are supposed to be heavier than the average starting
battery).

So is it your opinion that I was sold a bill of goods?


wrote in message
ups.com...

wrote:
I am reading a book called "Powerboater's Guide to Electronic Systems".
The book recommends using two dual-purpose batteries if the boat is a
center console. A dual purpose battery is supposed to be good for both
cranking the motor and serving as a house battery. I am wondering why
a dual purpose battery is the best kind for a center console, but not
the best for a cruising boat (he recommended a combination of a
starting battery and a deep cycle battery for a cruising boat). What
are the reasoning behind this? Won't a combination of a starting
battery and a separated deep cycle battery is just as good for a center
console?

My center console is having two dual-purpose batteries just like what
the book has recommended. I guess this is good. I just don't know why
this is good.

Thanks in advance for any info.

Jay Chan


Sounds like the "Powerboater's Guide to Electronic Systems" wasn't
written by a powerboater.

You've got some bad advice.

There is almost no earthly reason to ever have a "starting battery" on
a boat, except it will help the battery manufacturer sell a greater
number of batteries each year. Starting batteries have lighter weight
(thinner) plates so additional surface area can be exposed to the
electrolyte and maximize the CCA rating in a given case size. Those
thin plates disintegrate faster than the thicker plates in a "deep
cycle" battery, and when one plate is gone the battery is toast. The
thin plates make it bad practice to discharge a starting battery very
deeply- the recharge stresses the thin plates and leads to premature
battery failure.

(I use Rolls batteries on my boat. They are sold with a 10-year
warranty. Rolls doesn't even offer a "starting battery", and the
Rolls/Surette company is one of the premiere manufacturers of flooded
cell batteries.)

If space is so tight that you just can't possibly fit a deep cycle
battery rated for sufficient CCA, then I suppose a "starting" battery
must be used- but that situation will arise once in a couple of hundred
installations. In fact, if space is *that* tight, you battery
compartment is probably inadequately ventilated and you have some
other, potentially more serious problems.

Best plan: Always use a deep cycle battery for house loads. Use a deep
cycle battery with sufficient CCA to start your engine in nearly all
applications. Have at least two batteries, properly cabled and
switched.

"Reggie Smithers" wrote in message
...


I might have been sold a bill of goods (this wouldn't be the first time),
but I was told by boat/us that the Marine Dual Purpose Battery would have
the extra "cranking amps" for a longer period of time, than a Deep Cycle
Battery would provide. I have twin 5.7 gas engines, which require high
cranking amps.

I had the same twin engines on our 32 footer and never had a problem using
deep cycle. I did, however, opt for three group 3 batteries. They were
large and heavy.

The batteries were on a constant charge when on shore power with a 20 amp
trickle smartcharger.

I never had a problem starting or running equipment while away from the
dock, including overnighters anchored or moored on a buoy.

Thanks for all the good info that I have received here.

Based on the info here, I have a feeling that the auther of the boat
recommended the use of dual purpose batteries for a center console has
to do with this reason:

- The author didn't expect the use of a trolling motor in a center
console, and a center console tends not to have anything like a
refrigrator that uses a lot of amps. Therefore, he didn't think a
center console needs any deep cycle battery; then he could save money
and weight. This leaves the choice between starting batteries or dual
purpose batteries. At this point, I don't know why he didn't simply
suggest the use of one starting battery and one dual purpose battery
instead of two dual purpose batteries; he suggested the use of starting
batteries in other types of boats anyway; I don't see why he didn't
suggest the use of a starting battery in a center console. This seems
to be an inconsistence in his recommendation. May be he was trying to
simplify his recommendation; therefore, he said something simple like
this:
"For a center console, I recommend using two dual purpose
batteries."
instead of saying something complicated like this:
"For a center console, I recommend using two dual purpose
batteries or one starting battery and one dual purpose battery."

Based on the info that I have received here and the recommendation from
the book, I can say these:

- If I intend to use minimum electronic devices in a center console,
I can follow the "two dual purpose batteries" approach.

- If I intend to use a small number electronic devices (such as a
radio and a fishfinder) plus a 12-volt trolling motor in a center
console, I should use two deep cycle batteries and one of them must
have enough cranking power rating (CCA rating).

- If I intend to use a small number electronic devices plus a 12-volt
trolling motor in a center console, but the motor is the kind that I
need to crank a couple times before it can start, I should use two deep
cycle batteries and _both_ of them must have enough cranking power
rating (CCA rating). Am I understand this point correctly? Should I
use a combination of one dual purpose battery and one high CCA deep
cycle battery?

Seem like the question is "What kind of batteries should I use if the
motor is the kind that I need to crank a couple times"? No, the motor
in my boat is not like that. I am asking this just for educational
purpose.

Jay Chan


wrote:
I am reading a book called "Powerboater's Guide to Electronic Systems".
The book recommends using two dual-purpose batteries if the boat is a
center console. A dual purpose battery is supposed to be good for both
cranking the motor and serving as a house battery. I am wondering why
a dual purpose battery is the best kind for a center console, but not
the best for a cruising boat (he recommended a combination of a
starting battery and a deep cycle battery for a cruising boat). What
are the reasoning behind this? Won't a combination of a starting
battery and a separated deep cycle battery is just as good for a center
console?

My center console is having two dual-purpose batteries just like what
the book has recommended. I guess this is good. I just don't know why
this is good.

Thanks in advance for any info.

Jay Chan