Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 19-11-2010, 13:42   #16
Don't ask if you can't handle it
 
sailorboy1's Avatar

Cruisers Forum Supporter

Join Date: Jul 2007
Location: On the boat somewhere
Boat: Hunter 410
Posts: 12,311
Hell I'm not going to read all the replies as to the amps. I start my engine on the house batteries 90%+ of the time and never thought anything about it. If the inverter can run the mircowave or coffee pot off the house battery why would I even believe it couldn't start the engine.

I do switch it to the start battery once in a while prior to starting just to recharge it when leaving the mooring when I expect to only be running the engine for 5 minutes or so.
__________________

__________________
sailorboy1 is offline   Reply With Quote
Old 19-11-2010, 15:28   #17
Registered User
 
Connemara's Avatar

Join Date: Oct 2006
Location: Toronto, Canada
Boat: Mirage 27 in Toronto; Wright 10 in Auckland
Posts: 671
Images: 2
Quote:
Originally Posted by hellosailor View Post
...a federally licensed mathematician...<G>
How do you get one of them licenses? I was actually trained as a mathematician (back when dinosaurs roamed the earth) and if I had a license the Admiral might get off my back when I make adding mistakes.

More seriously, I use the two-bank system because I have occasionally drained a battery by running the stereo and a few other things for a day-long cruise. If I do that and forget to switch to the starter battery, I get that lovely solenoid click that says -- no juice.

I fear if I left the bank on All, I might drain both and be up the creek (or out on the lake) without a paddle.


Connemara
__________________

__________________
Connemara is offline   Reply With Quote
Old 19-11-2010, 15:35   #18
Moderator Emeritus
 
GordMay's Avatar

Join Date: Mar 2003
Location: Thunder Bay, Ontario - 48-29N x 89-20W
Boat: (Cruiser Living On Dirt)
Posts: 31,579
Images: 240
Quote:
Originally Posted by Maine Sail View Post
... a sufficient house bank of deep cycle batts should easily start most any small aux diesel engine the bank has been properly cared for.
Indeed!
__________________
Gord May
"If you didn't have the time or money to do it right in the first place, when will you get the time/$ to fix it?"



GordMay is offline   Reply With Quote
Old 20-11-2010, 05:33   #19
Registered User

Join Date: Jun 2007
Location: SW Florida
Boat: FP Belize, 43' - Dot Dun
Posts: 3,425
From Trojan's website

Trojan Battery Company

"
Can I use my Deep Cycle battery as a starting battery?

Deep cycle batteries can be used for engine starting but starting batteries should not be used for deep cycle applications. A deep cycle battery may have less cranking amps per pound than a starting battery, but in most cases a deep cycle battery is still more than adequate for the purpose of starting an engine.
"

I took this information as true, hence I start my starboard engine (3GM30) exclusively from the house bank.
__________________
DotDun is offline   Reply With Quote
Old 20-11-2010, 12:25   #20
Moderator
 
noelex 77's Avatar

Cruisers Forum Supporter

Join Date: Jul 2007
Location: Living on dirt waiting for our new yacht to be built.
Boat: Half built Bestevaer.
Posts: 10,619
Maine Sail I am puzzled why you are not measuring the much larger inrush currents reported by others. The inrush current is always going to be much larger than the steady state starting current by a factor of at least 5X. If I accept the conclusion that
Quote:
Originally Posted by Maine Sail View Post
. The peak loads captured are all between 130 to 180 amps in-rush.
The steady state starting current would be less than 26 to 36A.

As you are not convinced by the Blue Seas data here is another link
This link shows an inrush current of 1295 A measured on Isuzu C240PW


http://www.msha.gov/s&hinfo/techrpt/DIESEL/FUSE.pdf



It should be remembered that these inrush currents are very short duration. They are not to be confused with CCA ratings or the current carrying capacity of conductors. These specifications are for durations a couple of orders of magnitude higher.
I have to agree with David
Quote:
Originally Posted by djmarchand View Post

So I agree with the conclusion, but not the numbers.
__________________
noelex 77 is offline   Reply With Quote
Old 20-11-2010, 13:26   #21
Marine Service Provider
 
Maine Sail's Avatar

Join Date: Jan 2007
Location: Maine
Boat: CS-36T - Cupecoy
Posts: 3,060
Quote:
Originally Posted by noelex 77 View Post
Maine Sail I am puzzled why you are not measuring the much larger inrush currents reported by others. The inrush current is always going to be much larger than the steady state starting current by a factor of at least 5X. If I accept the conclusion that


The steady state starting current would be less than 26 to 36A.

As you are not convinced by the Blue Seas data here is another link
This link shows an inrush current of 1295 A measured on Isuzu C240PW


http://www.msha.gov/s&hinfo/techrpt/DIESEL/FUSE.pdf



It should be remembered that these inrush currents are very short duration. They are not to be confused with CCA ratings or the current carrying capacity of conductors. These specifications are for durations a couple of orders of magnitude higher.
I have to agree with David
Again, I measured it with a meter capable of capturing in-rush to 1/1000th of a second and those test show that the times are longer than my meter captures so unless it is broken I should be capturing good data. I bought this meter specifically to capture in-rush loads because I purchased one that claimed in-rush but that was not fast enough on DC.. Those engines referenced are all significantly larger than my small Mitsubishi and significantly larger than anything on most small sailboats. I never doubted Blue Seas data as I have seen it but that data can't be applied to all engines.

I still don't understand the point? Are you insinuating that deep cycle house banks can't start a motor because of a few milliseconds of in-rush current? On BIG engines you'll need BIG cranking amps but on small diesels you can still get BIG cranking amps compared to what the motor needs.

My whole point in this was that I had seen about my fourth set of fried diodes because boaters believe they NEED to start on the start battery then switch back to the house bank. They do not, in most cases and with most boats out there wired with a factory installed 1/2/BOTH/OFF switch the less switching you do the less chance you have of HEF (human error factor). I always prefer to re-wire the vessel so that fried diodes can't happen but some owners just don't want to spend the money.

These in-rush currents are insignificant to starting a small diesel off a sufficient house bank. Even if you did or do have a 1200 A peak, bigger engines certainly can, your cable and a 200 amp ANL fuse would still sustain this just fine as would your battery bank deep or starting.

I have measured in-rush currents over 1000 amps just not on small motors like mine. I measured over 1300A on a big John Deer marine engine in a lobster boat. The fisherman was using some old 6V batts from a floor polisher cause he got them for free. Motor started fine and the batts were 3 years old when he installed them. Lobstermen are tight with the buck. The biggest I have seen on small motors are the old Perkins engines but still not an issue for starting off a good house bank.

In the spring, when my boat un-thaws, I will again measure in-rush. I will use both the Extech and a Fluke to make sure they are in agreement. I still suspect it will be where it was a few years ago but either way it still does not matter to the original point.

BTW here is a pic of the bank of two T-105's and the big Cummins engine in our old power boat. Even in the icy cold temps, we left her in over the winter, the T-105's started that rather large beast of a motor without issue...
__________________
Marine How To Articles
Maine Sail is offline   Reply With Quote
Old 20-11-2010, 14:17   #22
Moderator
 
noelex 77's Avatar

Cruisers Forum Supporter

Join Date: Jul 2007
Location: Living on dirt waiting for our new yacht to be built.
Boat: Half built Bestevaer.
Posts: 10,619
Perhaps be better agree to disagree about the maximum starting current as I think it is probably an esoteric point of minor practical value to most boat owners.
I also reiterate I have enjoyed all your detailed posts over the years and even if I disagree about the measurements in this one I don’t want to discourage you from future articles.
To answer some of your points which may clarify things

Quote:
Originally Posted by Maine Sail View Post
.. Those engines referenced are all significantly larger than my small Mitsubishi and significantly larger than anything on most small sailboats. I never doubted Blue Seas data as I have seen it but that data can't be applied to all engines.
The link with a reported 1295A in rush current is measured on Isuzu C240PW
Which I believe is a 2.4L about 50hp (in marine form) engine
Quote:
Originally Posted by Maine Sail View Post
I still don't understand the point? Are you insinuating that deep cycle house banks can't start a motor because of a few milliseconds of in-rush current?
No I only disagree with measurement of 130 to 180A inrush current. The value is much higher than this, in the order of 1000A.

As David said I agree with the conclusion (About successfully starting with deep cycle batteries), but not the numbers (the maximum starting current)
__________________

__________________
noelex 77 is offline   Reply With Quote
Reply

Tags
engine

Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Before starting my engine after 19 yrs........ San Juan Sailor Engines and Propulsion Systems 4 14-09-2008 14:04
crank-starting a diesel engine- Safe or Unsafe spaceballs Engines and Propulsion Systems 17 04-09-2008 02:18
Video & Website w/ update of Day 10 Olympic sailing Lightfin General Sailing Forum 2 18-08-2008 20:24
Most powerful diesel engine in the world Comfortably Numb Engines and Propulsion Systems 5 19-10-2006 09:26
starting a business in 3rd world florensic Boat Ownership & Making a Living 7 13-01-2004 05:16



Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 03:13.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.