On Fri, 30 Dec 2005 11:55:19 -0500, Harry Krause
wrote:

And whatever you get, keep your
starting battery out of a trolling motor circuit.

====================================

Good advice. The trolling motor is the one device you mention that
could really benefit from a high quality deep cycle battery. I'm
partial to golf cart batteries (two 6 volt batts in series) for that
kind of application since they are designed for many charge/discharge
cycles.

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

wrote:
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


Harry Krause wrote:
Good grief. The price difference between a dual purpose and a deep cycle
in the Group 27 size you want is negligible. If you have a fairly new
outboard and it doesn't start by the second try, then you have something
wrong with the outboard, or your starting technique is wrong. Just buy
some batteries and be done with it. And whatever you get, keep your
starting battery out of a trolling motor circuit.

Will a deep cycle battery that also has a high cranking rating be able
to allow us to crank the motor for let's say 2 or 3 times? Again, I am
not planning to replace the existing dual purpose batteries in my boat.
I am asking this just for educational purpose.

Yes, I will keep the trolling motor out of the starting battery by
using a battery selector or by adding a deep cycle battery just for the
trolling motor.

Jay Chan

wrote in message
oups.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

wrote:
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


Harry Krause wrote:
Good grief. The price difference between a dual purpose and a deep cycle
in the Group 27 size you want is negligible. If you have a fairly new
outboard and it doesn't start by the second try, then you have something
wrong with the outboard, or your starting technique is wrong. Just buy
some batteries and be done with it. And whatever you get, keep your
starting battery out of a trolling motor circuit.

Will a deep cycle battery that also has a high cranking rating be able
to allow us to crank the motor for let's say 2 or 3 times?

Yes, without a problem.

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

wrote:
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


Harry Krause wrote:
Good grief. The price difference between a dual purpose and a deep cycle
in the Group 27 size you want is negligible. If you have a fairly new
outboard and it doesn't start by the second try, then you have something
wrong with the outboard, or your starting technique is wrong. Just buy
some batteries and be done with it. And whatever you get, keep your
starting battery out of a trolling motor circuit.

wrote
Will a deep cycle battery that also has a high cranking rating be able
to allow us to crank the motor for let's say 2 or 3 times?

JimH wrote:
Yes, without a problem.

Thanks. Seem like the determinating factor of the cranking capability
of a battery has to do with the CCA rating. If a deep cycle battery
has a good CCA rating, it is just as good as a starting battery for the
purpose of cranking a motor. This also means that there is little
reason to get a starting battery if not for saving money or saving
weight. This is good to know; the reason is that I am planning to get
a deep cycle battery for the trolling motor; I may as well get one that
has a good enough CCA rating; then I can use it as the second backup
battery for cranking motor just in case all other batteries got drained
by mistake.

Jay Chan