Cruisers Forum

Join CruisersForum Today

Thread Tools Rate Thread Display Modes
Old 26-07-2016, 09:34   #31
Senior Cruiser

Cruisers Forum Supporter

Join Date: Mar 2014
Location: Anacortes
Boat: previous - Whitby 42 new - Goldenwave 44
Posts: 1,570
Re: Alternator Choice Advice

This DC genset was installed on my boat by the previous owner. It is in a poor spot for weight and interference to getting to some things aft. It is no longer sold. I have the high output water pump for it (for a watermaker) but it was never installed.

It is a sweet, sweet genset though with a Balmar 275amp alternator. It came with a Lifeline regulator but I am swapping in a Balmar 614 instead. It purrs when running.

The manual PDF exceeds the file size for uploading so can't do it here.

exMaggieDrum is offline   Reply With Quote
Old 26-07-2016, 10:34   #32
Registered User
Sandero's Avatar

Join Date: Apr 2006
Location: Southern Westchester/Northport LI
Boat: Shiva - Contest 36s
Posts: 3,892
Re: Alternator Choice Advice

If you have alt charging sources and your batts are maintained pretty full... you likely will have a hard time.... lost of use with no serious charging... to run them down such that a high output alternator delivers its full potential. I never see anything like the 120 rating from my alternator... but the batts are usually almost topped up. When they are down it may push out 60-70 for a few minutes and then ramps down to 5 or 10 amps.

The whole electrical thing depends on how many amps you use typically and how you replace them...

Sandero is offline   Reply With Quote
Old 26-07-2016, 11:53   #33
Registered User
SailRedemption's Avatar

Join Date: Feb 2014
Location: New Orleans
Boat: Kaufman 47
Posts: 549
Re: Alternator Choice Advice

Just got off the phone with the wonderful gentleman at Balmar. He said they have put the 94 large case on my size engine before. Only things that will cause issue is the belt will need to be longer, the tension arm may need to be made better to accommodate the larger diameter or get theirs, and the belt cover will need to be removed or modified.

So I'm sold with that information regarding large case alternators as I didn't really want a second alternator on the engine and the expense that comes with it. I'll keep this updated as I go.

See more @
SailRedemption is offline   Reply With Quote
Old 26-07-2016, 12:01   #34
Registered User
Dsanduril's Avatar

Join Date: Aug 2011
Location: Oakland
Boat: Cross 40
Posts: 1,393
Re: Alternator Choice Advice

Way back up the thread the question of alternator core temperatures was raised. Here you go:

Click image for larger version

Name:	Alternator Temperature.PNG
Views:	37
Size:	115.3 KB
ID:	128449

This is for a standard small-case auto alternator running at full nominal field current and ambient temperature (on the test stand) of 23C. The case runs about 100C over ambient, and the windings about 40C over that. Note that removing the diodes from the case dropped the overall temperatures by about 20C.

The key in this (especially with LiFePO and other high-acceptance batteries) is finding a high-efficiency alternator. You bog standard auto alternator has (at best) an efficiency of about 50%, that means that if you are getting 1kW out of your alternator you are also using a 1kW heater on your alternator. Finding even a 60% efficient alternator makes a huge difference; to get the same 1kW output you reduce the heating element by 30% just by getting a 10% more efficient alternator.

For more than you ever wanted to know about temperatures in the various parts of the alternator:

MIT Alternator Temperature Modeling
Dsanduril is offline   Reply With Quote
Old 04-08-2016, 07:25   #35
Registered User

Join Date: Jan 2008
Posts: 122
Re: Alternator Choice Advice

Our two temperature regulated Balmar 150A small frame alts have worked well for years in tropical mexico. We have them both feeding an 860AH AGM bank and when charging from 50 to 80% SOC a sustained 225A is seen for an hour of charging. Thats 75% of nominal output. On a 90F day in the hot engine compartment, the temperature sensing regulator may back them off to 50% a total of 10 times during the hour of bulk charging it takes to get to 80%. This occurs whenever alt temp hits 107C. From 80% on, current drops and therefore no more back offs happen. The interesting thing is that the back offs during Bulk last exactly 30 secs each time and then full max current resumes. So the back offs are inconsequential to charging performance. For this reason I have never understood the presumed need for unwieldily large frame alternators. What's the advantage?

Sent from my iPhone using Cruisers Sailing Forum

Journeyman is offline   Reply With Quote


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
New boat- need advice on my Dinghy Choice!! msaltzman Auxiliary Equipment & Dinghy 44 19-03-2016 08:01
High Rated Alternator with Alternator to Battery Charger Rumbero Electrical: Batteries, Generators & Solar 113 18-07-2014 05:29
Getting New Headsail - Need Advice on Sail Choice fishfinder Monohull Sailboats 7 19-05-2010 00:34
more info for boat choice bob_deb Meets & Greets 6 08-03-2004 04:34

Our Communities

Our communities encompass many different hobbies and interests, but each one is built on friendly, intelligent membership.

» More about our Communities

Automotive Communities

Our Automotive communities encompass many different makes and models. From U.S. domestics to European Saloons.

» More about our Automotive Communities

Marine Communities

Our Marine websites focus on Cruising and Sailing Vessels, including forums and the largest cruising Wiki project on the web today.

» More about our Marine Communities

Copyright 2002-2015 Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 09:47.

Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2016, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2016, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.