"Scott Vernon" wrote in message
...
Yes, a deep cycle will start your Yanmar, but you are reducing the
life of the battery by doing so.

Not by enough that you would even notice it. A recreational boat
starts so seldom and a load of 80A isn't enough to do any harm.

There's a reason, other than marketing, why batteries are labeled
'starting' or 'deep cycle' or 'dual purpose'.
I believe the main difference is the thickness of the plates. Starter
batts, are built for short duration, high loads. DC are for less
load over a longer time period. DP are a compromise between the two.

All true.

Doug
s/v CAllista


--
Scott Vernon
Plowville Pa _/)__/)_/)_


"Roger Long" wrote in message
...
Is there any reason to consider using dual purpose or a one starting,
one deep cycle set up with a 20 hp Yanmar diesel? I would think the
starting loads on the small engine are low enough that two deep cycle
batteries would do fine.

--

Roger Long

I thinking about rotating both the hotel loads and the rather modest
starting loads between two deep cycle batteries so the get even
service. I'm aware of the problem with leaving them both connected if
there is an electrical leak or misjudgment about usage. This wouldn't
be as serious anyway as it would on a boat with an engine too big to
hand start.

--

Roger Long

"Doug Dotson" dougdotson@NOSPAMcablespeedNOSPAMcom wrote in message
...

"Scott Vernon" wrote in message
...
Yes, a deep cycle will start your Yanmar, but you are reducing the
life of the battery by doing so.

Not by enough that you would even notice it. A recreational boat
starts so seldom and a load of 80A isn't enough to do any harm.


Right, I agree. But, being in the MD area, I've got to consider
sometimes starting in cold weather and cranking more than usual.


--
Scott Vernon
Plowville Pa _/)__/)_/)_

Scott Vernon wrote:
"Doug Dotson" dougdotson@NOSPAMcablespeedNOSPAMcom wrote in message
...

"Scott Vernon" wrote in message
...

Yes, a deep cycle will start your Yanmar, but you are reducing the
life of the battery by doing so.

Not by enough that you would even notice it. A recreational boat
starts so seldom and a load of 80A isn't enough to do any harm.



Right, I agree. But, being in the MD area, I've got to consider
sometimes starting in cold weather and cranking more than usual.


Actually, I think the bigger issue is the non-starter loads. If the
boat has a fridge or other high house loads, you want to add house bank
capacity, which then makes it hard to do the "swap 1 & 2" trick. Once
you have dedicated banks it pays to use a proper starting battery.

OTOH, my previous boat had a finicky Westerbeke, which has a pre-heater,
and it never had a problem starting off a Surrette deep cycle.

On Tue, 11 Jan 2005 22:46:29 GMT, "Roger Long"
wrote:

I thinking about rotating both the hotel loads and the rather modest
starting loads between two deep cycle batteries so the get even
service. I'm aware of the problem with leaving them both connected if
there is an electrical leak or misjudgment about usage. This wouldn't
be as serious anyway as it would on a boat with an engine too big to
hand start.
Depends on how fast you need the engine started. Say there's a drunk
in a cigarette boat (or a tanker) bearing down on you. Or the wind
died and you have a 3 knot current pushing you on the rocks 50 yards
away. It's not that you have to have a motor ready for instant use to
go sailing. It's the situations you get into because you think you
have a motor ready for instant use.

That said, I sailed for more years than I'd care to remember using the
"rhythm system" for batteries as you describe. I did flatline the
system a couple of times by forgetting to switch from BOTH after
charging but it never got me in any trouble I couldn't get out of.
Regardless, I now have an idjit-proof system I'm much happier with.

Oh, and don't forget, batteries run other things than starters. Bilge
pumps, for example.
__________________________________________________ __________
Glen "Wiley" Wilson usenet1 SPAMNIX at world wide wiley dot com
To reply, lose the capitals and do the obvious.

Take a look at cpRepeater, my NMEA data integrator, repeater, and
logger at http://www.worldwidewiley.com/

I also live in the MD area (actually I live in MD proper) , and
"sometimes" isn't really a factor, and "cranking more than usual"
isn't either as long as it isn't the norm. I can start my engine at
freezing temps with maybe 5 revs rather than the normal 2. If your
engine requires alot of revs to start then a dedicated starting
battery is probably a good idea. But even so, 80A isn't a heavy load
for a decent deep cycle battery. I draw 50A to run the refrigeration
and 100A to run the microwave.

Doug
s/v Callista

"Scott Vernon" wrote in message
...

"Doug Dotson" dougdotson@NOSPAMcablespeedNOSPAMcom wrote in message
...

"Scott Vernon" wrote in message
...
Yes, a deep cycle will start your Yanmar, but you are reducing the
life of the battery by doing so.

Not by enough that you would even notice it. A recreational boat
starts so seldom and a load of 80A isn't enough to do any harm.


Right, I agree. But, being in the MD area, I've got to consider
sometimes starting in cold weather and cranking more than usual.


--
Scott Vernon
Plowville Pa _/)__/)_/)_

My outlook is probably effected somewhat by watching the motorcycle
size battery in my plane start the 160 HP, high compression, engine
briskly on even below zero days.

BTW the 1,2 Both switch is an anachronism that I'll be ditching as
soon as I can get the boat back to Maine and overhaul the whole
system. There are very inexpensive battery management and charging
systems now that charge the batteries while leaving them isolated from
each other for normal loads.

--

Roger Long



"Glen "Wiley" Wilson" wrote in
message ...
On Tue, 11 Jan 2005 22:46:29 GMT, "Roger Long"
wrote:

I thinking about rotating both the hotel loads and the rather modest
starting loads between two deep cycle batteries so the get even
service. I'm aware of the problem with leaving them both connected
if
there is an electrical leak or misjudgment about usage. This
wouldn't
be as serious anyway as it would on a boat with an engine too big to
hand start.
Depends on how fast you need the engine started. Say there's a
drunk
in a cigarette boat (or a tanker) bearing down on you. Or the wind
died and you have a 3 knot current pushing you on the rocks 50 yards
away. It's not that you have to have a motor ready for instant use
to
go sailing. It's the situations you get into because you think you
have a motor ready for instant use.

That said, I sailed for more years than I'd care to remember using
the
"rhythm system" for batteries as you describe. I did flatline the
system a couple of times by forgetting to switch from BOTH after
charging but it never got me in any trouble I couldn't get out of.
Regardless, I now have an idjit-proof system I'm much happier with.

Oh, and don't forget, batteries run other things than starters.
Bilge
pumps, for example.
__________________________________________________ __________
Glen "Wiley" Wilson usenet1 SPAMNIX at world wide wiley dot com
To reply, lose the capitals and do the obvious.

Take a look at cpRepeater, my NMEA data integrator, repeater, and
logger at http://www.worldwidewiley.com/

Roger Long wrote:

snip There are very inexpensive battery management and charging
systems now that charge the batteries while leaving them isolated from
each other for normal loads.



It seems Glen and I have gone down similar paths...
If I'm understanding him, both of us _suggest_ the same thing - keep
engine starting energy available in a starting battery.
It gives you both house batteries to draw down without hand starting.
It's not only about the 1-B-2 switch.
Go ahead , use one of those motorcycle size starting duty batteries
instead of another ball buster - you have the house batteries as backup
for hard starting (a second level contingency) if you ever need it.
Just get enough CCA for the job...
It's like buying a little insurance...
Three-way isolation is pretty straight forward - except for non-matching
battery banks with accelerated (smart) charging.

Or do what a large percentage of owners do - live with the dual-battery
discharge rules you suggest (and the outcomes).
As you know, you'll face lot's of compromise decisions as you finish her
out to your satisfaction (not ours).
You will probably live thru whatever decision you make as we all have up
to this point.

Skip

On Wed, 12 Jan 2005 00:53:58 GMT, "Roger Long"
wrote:

My outlook is probably effected somewhat by watching the motorcycle
size battery in my plane start the 160 HP, high compression, engine
briskly on even below zero days.

Not quite what I meant. I'm talking about how long it takes to hand
crank the engine if you manage to flatline both batteries, which you
eventually will do following the protocol you mentioned.

BTW the 1,2 Both switch is an anachronism that I'll be ditching as
soon as I can get the boat back to Maine and overhaul the whole
system.

Which was my point.
__________________________________________________ __________
Glen "Wiley" Wilson usenet1 SPAMNIX at world wide wiley dot com
To reply, lose the capitals and do the obvious.

Take a look at cpRepeater, my NMEA data integrator, repeater, and
logger at http://www.worldwidewiley.com/

"Roger Long" wrote in message
.. .
My outlook is probably effected somewhat by watching the motorcycle size
battery in my plane start the 160 HP, high compression, engine briskly on
even below zero days.

Most aircraft batteries (even if motorcycle size) are AGM or gel. High
energy density for their size. Also, I assume that you preheat your engine
on your aircraft prior to starting.. All aircraft I have piloted require
preheat prior to starting to minimize excessive wear while the oil
decides to be useful. So most aircraft engines are not actually started at
zero temps.

BTW the 1,2 Both switch is an anachronism that I'll be ditching as soon as
I can get the boat back to Maine and overhaul the whole system.

Agreed. An antiquated concept.

There are very inexpensive battery management and charging systems now
that charge the batteries while leaving them isolated from each other for
normal loads.

Not exacty inexpensive but worth it.

--

Roger Long


Doug
s/v Callista