Cruisers Forum
 


Join CruisersForum Today

Reply
  This discussion is proudly sponsored by:
Please support our sponsors and let them know you heard about their products on Cruisers Forums. Advertise Here
 
Thread Tools Search this Thread Rate Thread Display Modes
Old 28-02-2019, 23:49   #1
Registered User

Join Date: May 2018
Location: Washington DC
Boat: Bristol 30
Posts: 84
Alternator pulley question

Hi,
Newbie question here. I'm trying to get more juice out of my alternator at low RPMs and idle. I am running a Mando / ARCO 60055 alternator on an Atomic 4. I'm trying to figure out how to change the pulley ratio of the alternator. Do I change the alternator side, or the pulley side? If I'm switching out the alternator pulley, how do I go about looking for a pulley that fits?
__________________

__________________
Bristol 30 S/V Sonora del Viento
Dancing with Sonora
svsonora is offline   Reply With Quote
Old 01-03-2019, 00:31   #2
Registered User

Join Date: Oct 2008
Boat: Custom cutter, 42'
Posts: 500
Re: Alternator pulley question

A smaller pulley on the alternator will spin it faster. This can be done, with the provision that you can only go so small on the pulley before the small diameter causes problems by bending the belt into too small of a radius. Assuming you are running an "A" size belt (1/2" wide) the smallest pulley available is 2.5" OD. I'd advise running a bit larger diameter than that. Measure the diameter of the alternator shaft and buy a pulley that matches that diameter. The pulley should be a press fit on the alternator shaft.
__________________

Pauls is offline   Reply With Quote
Old 01-03-2019, 00:34   #3
Registered User

Join Date: Dec 2009
Location: Australia
Boat: building Roberts Mauritius 43ft
Posts: 1,233
Re: Alternator pulley question

I've just been through this exercise but mine was more complicated as I went from a single groove to a double groove pulley and I had to get it machined.

You could change the size of either pulley on the engine or the alternator but my preference would be for the alternator. There are a number of ways you could go about it but my advice is that you take the pulley off the alternator and take it to a pulley specialist in your area.

Maybe one of these?
https://www.thomasnet.com/washington...3910806-1.html

You may well have to modify the tensioning arrangement.

(I found the pulley specialists incredibly helpful back here in Perth West Australia)
coopec43 is offline   Reply With Quote
Old 01-03-2019, 00:41   #4
Senior Cruiser
 
Dave_S's Avatar

Cruisers Forum Supporter

Join Date: Jun 2016
Location: Brisbane Australia
Boat: Schionning Waterline 1480
Posts: 1,240
Re: Alternator pulley question

My 0.02c

Alternators can electronically tap out at a preset output so no matter how fast you spin it it won't make more current except when engine revs are low.
__________________
Regards
Dave
Dave_S is offline   Reply With Quote
Old 01-03-2019, 02:09   #5
Registered User
 
Hesti's Avatar

Join Date: Nov 2018
Location: North Germany
Boat: 29 ft
Posts: 99
Re: Alternator pulley question

Take care that the alternator does not exceed its max. RPM at max. engine revs. Actually, it is a good idea if it always stays somewhat below these max. RPM - alternators do not like being overspun, either the bearings will give in pretty soon or the rotor may open up and touch the stator. A next size up alternator - if available - might be a solution.


In case you change the pulley: Make sure it is torqued to the manufacturer recommendation. Just saying. Speaking about car style alternators - pulleys flying of at high rpm or shafts breaking are not a joke. About press fit - on the alternators I know, the pulley is not a press fit on the shaft, torquing the pulley nut to manufacturer recommendation is the key.
Hesti is offline   Reply With Quote
Old 01-03-2019, 14:45   #6
Registered User

Join Date: Dec 2009
Location: Australia
Boat: building Roberts Mauritius 43ft
Posts: 1,233
Re: Alternator pulley question

I did find in Perth (West Australia) there are pulley distributors who stock pulleys for particular make/model of cars/boats. If you can't provide that detail they don't want to know you.

But there are other pulley distributors who can supply to a particular requirement: diameter, number of grooves, shaft diameter etc: they are not interested in make/model.
coopec43 is offline   Reply With Quote
Old 03-03-2019, 05:10   #7
Moderator
 
a64pilot's Avatar

Cruisers Forum Supporter

Join Date: Oct 2013
Location: Albany Ga.
Boat: Island Packet 38
Posts: 26,863
Re: Alternator pulley question

Average marine motor doesnít even come close to spinning an alternator at optimum RPM, not even close.
A lot of this is due to the size of engine pulley required to gear the alternator correctly would make it harder to fit into a boat.
One of the biggest reasons to spin one faster is to improve cooling, they are fan cooled and the faster fan cools better.

Average alternator is capable of 12,000 RPM and some can go to 18,000.
Measure your pulleys to determine the ratio and determine RPM.
a64pilot is offline   Reply With Quote
Old 03-03-2019, 22:55   #8
Registered User

Join Date: Apr 2007
Location: Australia
Boat: Island Packet 40
Posts: 2,883
Images: 7
Re: Alternator pulley question

Be mindful that the smaller the pulley you put on the alternator the greater the lateral load on the shaft and bearing becomes.
RaymondR is offline   Reply With Quote
Old 04-03-2019, 04:31   #9
Moderator
 
a64pilot's Avatar

Cruisers Forum Supporter

Join Date: Oct 2013
Location: Albany Ga.
Boat: Island Packet 38
Posts: 26,863
Alternator pulley question

Quote:
Originally Posted by RaymondR View Post
Be mindful that the smaller the pulley you put on the alternator the greater the lateral load on the shaft and bearing becomes.


Yes, but there is even more to it than that, the smaller pulley will stress the belt more, and as itís smaller there will be less contact area, and I can almost guarantee slippage and belt dust, plus slippage due to friction overheats the input shaft of the alternator and may burn out bearings, beside adding heat to something your trying to cool down by spinning it faster.
Unless you have some kind of unusual oversized pulley to start with, going smaller really isnít an option, they are about as small as you can get away with to start.
__________________

a64pilot is offline   Reply With Quote
Reply

Tags
alternator

Thread Tools Search this Thread
Search this Thread:

Advanced Search
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
Removing/Replacing Pulley Nut -- School Bus Alternator Dockhead Electrical: Batteries, Generators & Solar 18 31-08-2017 19:02
New Alternator/pulley system Mardagan Electrical: Batteries, Generators & Solar 5 27-08-2015 19:13
High Amp Alternator - Dedicated Double Pulley Belt dadidoc Electrical: Batteries, Generators & Solar 48 28-10-2011 05:34
High-Powered Alternator V Pulley crazyhorse77 Electrical: Batteries, Generators & Solar 16 17-12-2010 12:25
pulley/rpm/math question JusDreaming Plumbing Systems and Fixtures 1 28-06-2007 06:42

Advertise Here


Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 06:43.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
×

ShowCase vBulletin Plugins by Drive Thru Online, Inc.