Roger Long wrote:
I understand that but, is the load on a 20 hp diesel that you can
start by hand high enough to significantly reduce the life of the
battery?


What's the voltage drop when starting? Starting batteries can see surges
bring them down to as low as 8 volts and bounce back just fine. DC
batteries don't like this.

I'm not sure where the cut-off is, but if the starting load drops your
voltage down below 10, or maybe 10.5 (assuming that you've got a good
current path to starter & ground), then you might consider staying with
a start battery.

Fresh Breezes- Doug King

I'll let you know when I get the boat

My first two batteries are free, (and therefore probably minimum
quality) when the boat is delivered. Since this boat will seldom, if
ever, see shore power and often sail on and off its mooring, one of my
first projects will be a complete upgrade of the whole power system.
This will probably involve moving to sealed batteries in the bilge
since these boats are stern heavy and a bit tender. I'll also probably
put in a solar trickle system.

--

Roger Long



"DSK" wrote in message
...
Roger Long wrote:
I understand that but, is the load on a 20 hp diesel that you can
start by hand high enough to significantly reduce the life of the
battery?


What's the voltage drop when starting? Starting batteries can see
surges bring them down to as low as 8 volts and bounce back just
fine. DC batteries don't like this.

I'm not sure where the cut-off is, but if the starting load drops
your voltage down below 10, or maybe 10.5 (assuming that you've got
a good current path to starter & ground), then you might consider
staying with a start battery.

Fresh Breezes- Doug King

On Wed, 12 Jan 2005 12:24:16 GMT, "Roger Long"
wrote:
I'll let you know when I get the boat

My first two batteries are free, (and therefore probably minimum
quality) when the boat is delivered. Since this boat will seldom, if
ever, see shore power and often sail on and off its mooring, one of my
first projects will be a complete upgrade of the whole power system.
This will probably involve moving to sealed batteries in the bilge
since these boats are stern heavy and a bit tender. I'll also probably
put in a solar trickle system.

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

With my last boat I used 6 volt golf cart batteries for both starting
and a house bank driving a large inverter. The engines were 350 hp,
454 cubic inch V8s, and they never had a problem cranking, even in
freezing weather.

In article ,
"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.

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

There is a BIG difference between a DIESEL engine and a Gasoline engine,
when starting in cold weather. Comparing the two is "Apples and Oranges"
A diesel has a higher Compression Ratio than a Gas engine. Gas
volitilizes at a much lower temp than diesel fuel. Gas engines have
Spark Plugs that ignite the fuel/air mixture, and provides the required
heat of ignition. In a diesel with no glowplugs the only heat generated
is the Heat of Compression, which takes a while to build in the cyl.
That's why they invented Glow Plugs, and Intake Air Manifold Heaters,
to heat the fuel/air past the ignition temp.

Me

Glowplugs, etc are a feature of indirect injected engines. Many
smaller diesels are direct injected and do not require glowplugs. My
Perkins 85HP will start almost instantly even with temps below freezing.

Doug
s/v CAllista

"Me" wrote in message
...
In article ,
"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.

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

There is a BIG difference between a DIESEL engine and a Gasoline engine,
when starting in cold weather. Comparing the two is "Apples and Oranges"
A diesel has a higher Compression Ratio than a Gas engine. Gas
volitilizes at a much lower temp than diesel fuel. Gas engines have
Spark Plugs that ignite the fuel/air mixture, and provides the required
heat of ignition. In a diesel with no glowplugs the only heat generated
is the Heat of Compression, which takes a while to build in the cyl.
That's why they invented Glow Plugs, and Intake Air Manifold Heaters,
to heat the fuel/air past the ignition temp.

Me

There is a BIG difference between a DIESEL engine and a Gasoline
engine,
when starting in cold weather.

I don't plan on starting my sailboat engine in weather as cold as I
fly my plane in. That's for sure!

--

Roger Long

I assume you have to preheat your aircraft engine in cold temps. I had to
preheat mine in anything below 40F. I've never seen a diesel engine in
a plane either.

Doug
s/v Callista


"Roger Long" wrote in message
...

There is a BIG difference between a DIESEL engine and a Gasoline engine,
when starting in cold weather.

I don't plan on starting my sailboat engine in weather as cold as I fly my
plane in. That's for sure!

--

Roger Long

On Thursday 13 January 2005 12:29 am in rec.boats.cruising Doug Dotson
wrote:

I assume you have to preheat your aircraft engine in cold temps. I had to
preheat mine in anything below 40F. I've never seen a diesel engine in
a plane either.

They are available, at least in Europe.
The advantage is that they run on turbine fuel rather than
avgas which is often hard to find.

--
My real address is crn (at) netunix (dot) com
WARNING all messages containing attachments or html will be silently
deleted. Send only plain text.

Doug Dotson wrote:
I assume you have to preheat your aircraft engine in cold temps. I had to
preheat mine in anything below 40F. I've never seen a diesel engine in
a plane either.


Most of the dirigibles had diesel engines, and the German air force had
diesel powered planes including at least one fighter.

http://www.csd.uwo.ca/~pettypi/elevo...ther/ju86.html

Modern developments in metallurgy and turborcharging may bring the
diesel back into aero prominence

http://www.deltahawkengines.com/diesel00.htm

Just poking around finding interesting stuff on the wwweb. Beats working!

DSK

On Wed, 12 Jan 2005 02:27:05 GMT, Skip wrote:

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.

Dual batteries are working fine for me on an Atomic 4 gas engine, and
the system is simple, if not idiot proof. As insurance for those times
I may be an idiot, I carry a "booster pack" which is a sealed battery
complete with jumper cable style clamps and all the appropriate
switching, available at automotive suppliers for around US$50. Light,
cheap, simple and I can use it to boost my car in the winter.

Ryk