Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 10-09-2011, 11:22   #61
Registered User
 
ADMPRTR's Avatar

Join Date: Jan 2011
Location: Georgian Bay, Ontario, Canada
Boat: CS36 Traditional
Posts: 551
Re: Alternators - What's the Difference?

Quote:
Originally Posted by GordMay View Post
DIESEL: If you are driving your alternator with a diesel engine, and assuming adequate flywheel mass and a 3:1 engine drive pulley to alternator pulley ratio, a high efficiency, high current, 12V alternator will require about 1 hp per 30 amps of output power + about 1-2 hp for increased engine operating loads; when operating at its maximum rated output current.
Therefore, for a 150 Amp alternator, operating at full output, the expected diesel engine load would be about 7-8 hp.

GASOLINE: If using a gasoline engine instead of a diesel, with a slightly lower 2 to 2.5:1 drive ratio, figure on a requirement of about 1 hp per 15 amps of output power + about 1-3 hp for increased engine operating loads.
Hence, about 11-14 hp for a 150A alternator.
That is quite a difference. Is it just because of the drive ratio?
__________________

__________________
ADMPRTR is offline   Reply With Quote
Old 10-09-2011, 11:24   #62
Moderator Emeritus
 
GordMay's Avatar

Join Date: Mar 2003
Location: Thunder Bay, Ontario - 48-29N x 89-20W
Boat: (Cruiser Living On Dirt)
Posts: 31,583
Images: 240
Re: Alternators - What's the Difference ?

From
Water power - by Nigel Calder (August 17, 2009)

“... Water generators kick in at about 3 knots of boatspeed. Once boatspeed reaches about 6 knots, even a small water generator, such as the Aquair taffrail generator (Ampair Wind, Hydro and Packaged Power specialists +44 (0) 1258 837 266), can produce 5 amps at 12 volts (60 watts). At higher speeds, energy production increases proportionally faster than boatspeed ...”

More ➥ Creating hydroelectric power while cruising
__________________

__________________
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 10-09-2011, 11:46   #63
Registered User
 
ADMPRTR's Avatar

Join Date: Jan 2011
Location: Georgian Bay, Ontario, Canada
Boat: CS36 Traditional
Posts: 551
Re: Alternators - What's the Difference ?

Quote:
Originally Posted by Kettlewell View Post
I have mine set up so that all charging sources (solar and alternator) go directly to the large house bank. I have a dedicated starting battery that gets its charge via a Trik L Start from the house bank when there is excess charging going into that bank. Typically, the starter battery requires very little charging. You shouldn't be cranking your engine over for very long--if you are there is something wrong! Of course there are various switches to parallel battery banks if I need to and to shut them off too.
That sounds like a good setup. Then you don't have to switch banks (which we do and often forget to change so we are running house off the starter or the starter off the house) but you can still keep the batteries equalized.

Quote:
Originally Posted by Kettlewell View Post
On your earlier question about the depth of discharge vs. life of the battery bank. I believe the current thinking is that with traditional wet deep cycle batteries you get the most amps per $ over the lifetime of the batteries if your typical discharge is about 50% of capacity.
Thanks. When targeting 50% load does one look at the Amp Hour rating or the Reserve Capacity?
__________________
ADMPRTR is offline   Reply With Quote
Old 10-09-2011, 12:00   #64
Senior Cruiser
 
DeepFrz's Avatar

Cruisers Forum Supporter

Join Date: Mar 2006
Location: Winnipeg
Boat: None at this time
Posts: 7,930
Re: Alternators - What's the Difference ?

Quote:
I believe the current thinking is that with traditional wet deep cycle batteries you get the most amps per $ over the lifetime of the batteries if your typical discharge is about 50% of capacity.
I think that is right. Fewer charge cycles but maybe a longer overall life span.
__________________
DeepFrz is online now   Reply With Quote
Old 10-09-2011, 12:09   #65
Senior Cruiser

Cruisers Forum Supporter

Join Date: Aug 2009
Location: between the devil and the deep blue sea
Boat: a sailing boat
Posts: 17,314
Re: Alternators - What's the Difference ?

Quote:
Originally Posted by GordMay View Post

There were 10SI alternators with 37 Amp, 42A, 55A, 61A, and 63A ratings. The 12SI series were built with 56 Amp, 66A, 78A, and 94A maximum output ratings.
Are there any small delco alternators made today? I was to delco-remy site and all they offer are the bigger toys.

THX.
b.
__________________
barnakiel is offline   Reply With Quote
Old 10-09-2011, 12:18   #66
Registered User

Join Date: Jul 2006
Posts: 3,949
Re: Alternators - What's the Difference ?

You can buy essentially brand new rebuilts matching any Delco at any auto parts store. They are also widely available online. I have a 94-amp 12SI on my engine right now I bought at my local Advance Auto. You can also easily find any parts for these just about anywhere in the world and do the rebuild yourself. I had one rebuilt on an island in Honduras--actually they had to put it on a plane to fly it to the mainland and back to get it rebuilt. Took overnight and the entire cost including the plane was $50. I had another rebuilt in Cartagena.

Here's one good source.
__________________
Kettlewell Cruising
Kettlewell is offline   Reply With Quote
Old 10-09-2011, 12:33   #67
Registered User
 
ADMPRTR's Avatar

Join Date: Jan 2011
Location: Georgian Bay, Ontario, Canada
Boat: CS36 Traditional
Posts: 551
Re: Alternators - What's the Difference ?

Quote:
Originally Posted by Kettlewell View Post
You can also easily find any parts for these just about anywhere in the world and do the rebuild yourself. I had one rebuilt on an island in Honduras--actually they had to put it on a plane to fly it to the mainland and back to get it rebuilt. Took overnight and the entire cost including the plane was $50. I had another rebuilt in Cartagena.
What exactly is occurring when rebuilding an alternator? How does one know when to rebuild vs replace?
__________________
ADMPRTR is offline   Reply With Quote
Old 10-09-2011, 13:14   #68
Registered User

Join Date: Jul 2006
Posts: 3,949
Re: Alternators - What's the Difference ?

Many alternators are easy to rebuild. The most common parts to go are the diode packs and the regulators, if they use internal ones. Eventually the bearings go, but that is usually after many decades on a boat. Sometimes the windings burn out. All of these things can be repaired easily and relatively cheaply. On these old Delcos any cruiser can easily replace the diodes and the regulators themselves without any special tools, and I always carry spares. Any starter/alternator shop can replace the bearings and windings for a reasonable fee. This is the way these things used to be fixed before everybody decided that it is cheaper to buy new/rebuilds made in China or Mexico. That's why there is a "core charge" if you don't bring in your old alternator when you buy a new one at an auto parts place. They send the cores off someplace to be rebuilt.
__________________
Kettlewell Cruising
Kettlewell is offline   Reply With Quote
Old 10-09-2011, 13:39   #69
Moderator Emeritus
 
GordMay's Avatar

Join Date: Mar 2003
Location: Thunder Bay, Ontario - 48-29N x 89-20W
Boat: (Cruiser Living On Dirt)
Posts: 31,583
Images: 240
Re: Alternators - What's the Difference ?

Quote:
Originally Posted by DeepFrz View Post
I think that is right. Fewer charge cycles but maybe a longer overall life span.
We are actually interested in the lifetime power output.
That would equate to number of cycles x Amp/Hours per cycle.

A 50% DOD sounds about right for best cost of lifetime energy. Someone did a very good analysis of this very question - but, I cannot recall who.
__________________
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 10-09-2011, 14:16   #70
Senior Cruiser

Cruisers Forum Supporter

Join Date: Aug 2009
Location: between the devil and the deep blue sea
Boat: a sailing boat
Posts: 17,314
Re: Alternators - What's the Difference ?

Guys,

The smaller Delco - 63 A (I guess) - is it still manufactured? If not, does anybody know of a good clone?

THX,
barnie
__________________
barnakiel is offline   Reply With Quote
Old 10-09-2011, 14:26   #71
Registered User

Join Date: Jul 2006
Posts: 3,949
Re: Alternators - What's the Difference ?

Which Delco are you talking about? You need to provide the series like 10SI or 12SI, but yes they are almost certainly available either rebuilt or new clones from Mexico most likely. If you can post a photo I can probably tell you more certainly. Don't have the links right here, but later I'll try to post up some explaining the various Delcos better.
__________________
Kettlewell Cruising
Kettlewell is offline   Reply With Quote
Old 10-09-2011, 14:57   #72
Moderator Emeritus
 
GordMay's Avatar

Join Date: Mar 2003
Location: Thunder Bay, Ontario - 48-29N x 89-20W
Boat: (Cruiser Living On Dirt)
Posts: 31,583
Images: 240
Re: Alternators - What's the Difference ?

Quote:
Originally Posted by barnakiel View Post
The smaller Delco - 63 A (I guess) - is it still manufactured? If not, does anybody know of a good clone?
The Delco 10SI Series is a 12 Volt Internally Regulated Alternator. There were 10SI alternators with 37amp, 42amp, 55amp, 61amp, and 63amp ratings.
Clock position of the SI series of alternators is determined by viewing the alternator from the rear, with the threaded mounting hole straight up. With this view, the receptacle for the two wire plug-in connector will point to any one of the four available “CLOCK” positions. Straight up is 12:00, to the right is 3:00, straight down is 6:00, and to the left is 9:00.

http://www.delcoremy.com/Documents/A..._10510589.aspx

Yes, the 10SI has been (often) cloned:
Delco Replacement Alternator for 10SI Series*-*Arrowhead*ADR0239
__________________
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 10-09-2011, 15:05   #73
Senior Cruiser

Cruisers Forum Supporter

Join Date: Aug 2009
Location: between the devil and the deep blue sea
Boat: a sailing boat
Posts: 17,314
Re: Alternators - What's the Difference ?

Quote:
Originally Posted by Kettlewell View Post
Which Delco are you talking about? You need to provide the series like 10SI or 12SI
I was thinking of the Delco that (I believe) is 10SI. It may be their smallest unit. I would like one of them for a back-up / replacement of what we have. But I cannot find new ones on the web. They seem to have given up on on the smaller units.

b.
__________________
barnakiel is offline   Reply With Quote
Old 10-09-2011, 15:46   #74
Moderator
 
Pete7's Avatar

Cruisers Forum Supporter

Join Date: Aug 2009
Location: Solent, England
Boat: Moody 31
Posts: 8,561
Images: 14
Re: Alternators - What's the Difference ?

Quote:
Originally Posted by ADMPRTR View Post
So it is beneficial to somewhat over estimate the load requirements but not to go crazy. Good to know. Thanks.

The second part of the question is should the alternator be sized to the usage or the bank size or a combination of both?
The usage, because that is what you need to replace. Doesn't matter if you are putting a 100 AH back into a 500 or a 1000 amp bank it's still the same 100 AH.

Something else to consider and there was a recent post on here about a 80 ah alternator overheating on a yacht, is this: That 200 amp alternator takes 6hp or so and generates all those lovely amps. What about the heat generated by that huge alternator? the one that is mounted in the enclosed engine bay with little air cooling? its the same as sticking an alternator booster on an existing alternator to raise the voltage thereby reducing the charging time. You don't get something for nothing, work a small alternator hard and it will get hot. Doesn't matter in a car driving down the road it gets lots of cool clean air, now stick it in a yacht sealed in a box you could put a flat plate on top and cook eggs for breakfast on it.

Final thought, asking a 40hp engine to produce 6hp to run a large alternator isn't good for the engine as it's running under light load.

Pete
__________________
Moody 31 - April Lass
Pete7 is offline   Reply With Quote
Old 10-09-2011, 16:08   #75
Registered User
 
Nauticatarcher's Avatar

Join Date: Jun 2007
Location: Mooloolaba, Qld
Boat: Islander Freeport 36
Posts: 396
Re: Alternators - What's the Difference ?

One thing that must be looked at with alternators is their output/RPM figures, look at your pulley ratios and work out what the alternator RPM will be at your normal engine RPM, then see what alternator out put will be, in most cruising yachts alternators will spin at a lot lower rpm than usual and will not give anywhere near their rated output even with a smart reg (which is a must), the upside to this is longevity, also if your engine tachometer comes off your alternator you will have to consider recalibration if you alter alternator rpm
__________________

__________________
Nauticatarcher is offline   Reply With Quote
Reply

Tags
alternator

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
Does the colour of canvas make a difference ? plottie Construction, Maintenance & Refit 44 30-05-2012 04:28
'Distance to Waypoint' Difference janp391 OpenCPN 1 02-09-2011 09:24
Somali Cruises (with a Difference) Book Early neelie Off Topic Forum 0 20-07-2011 03:34



Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 13:39.


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.