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?

--

Roger Long



"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.

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.


--
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 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?

It depends on what you're using your boat for. If you're starting &
stopping your engine frequently, then maybe a starter battery makes sense.
But while cruising and using my 3GM30 (actually 27 hp) all I used were deep
cycles and they worked fine.

Another topic, one maybe you've thought about already, is how well the
alternator on your Yanmar is charging your batteries. If your charging
system isn't up to snuff, doesn't matter what batteries you're using, you'll
never get full cranking amps out of your batteries.

Paul

Define 'significantly'. If you're starting only once in a while, as
most sailboats do, I doubt that you'll notice the shortened life.
Are you buying new batts, or are there 2 DC already in your boat?

I had the separate start batt and a DC, When the DC went , I replaced
with a DP (that's all the local Sears stocks anymore). When the
starter batt goes away, I'll go with a second DP. I have a manual
separator switch.


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


"Roger Long" wrote in message
...
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?

--

Roger Long



"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.

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.


--
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

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.