Cruisers Forum
 


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 22-12-2014, 18:22   #91
Registered User
 
DeepFrz's Avatar

Cruisers Forum Supporter

Join Date: Mar 2006
Location: Winnipeg
Boat: None at this time
Posts: 8,462
Re: Highest Output Alternator

As battery capacity is rated in AH using the term 50 AH per day is perfectly acceptable. It just means that, for instance, if you have a 100 AH battery that you have drawn it down by 50 AH in a single 24 hr. period. It is not the same as using the term knots per hr.

Hello Nick, great to see you back.
DeepFrz is offline   Reply With Quote
Old 22-12-2014, 18:28   #92
Marine Service Provider
 
Maine Sail's Avatar

Join Date: Jan 2007
Location: Maine
Boat: CS-36T - Cupecoy
Posts: 3,197
Re: Highest Output Alternator

Quote:
Originally Posted by rwidman View Post
You need to understand a little more about electricity. By definition, an amp hour (AH) is an amp of current flowing for one hour. An amp flowing for 24 hours (a day) would be 24 amp hours. Two amps flowing for 24 hours would be 48 amp hours, etc. It doesn't make sense to say "50 Ah a day".

The current consumed by your AP is the amount of current consumed by the AP multiplied by the hours used. If it draws two amps and runs eight hours, it has consumed 16 amps.

He did not say 50 amps per day

He did not say 50 amps per hour

He correctly identified that his autopilot alone uses a 50 ampere hours each day plus or on top of his other loads.. This AP consumption is actually not too bad for a sail boat at sea..

His fridge might use another 60 Ah's each day and the rest of the equipment another 40 Ah's each day. Add the three together and he's using 150 ampere hours each 24 hour period.

If you don't define how many ampere hours are used in what time period you only have half the story....

If he had said my AP uses 50Ah the question from most would have been; How long does it take to consume those 50Ah's? Four hours, 1 day a week?

I don't see why you felt the need to chastise the OP for how many ampere hours his AP uses per day when there is really nothing wrong with the way he identified the AP's consumption...?

Quote:
Originally Posted by JoeFish View Post
I'm looking for a new alternator for our motor.

In a perfect world I'd like to find one that I can push a lot of amps into our house batteries quickly, as I sail on AP a lot and that tends to suck up about 50Ah a day plus all the other normal loads from radios, instruments, etc. (I'll admit we use far less in that department than some).
__________________
Marine How To Articles
Maine Sail is offline   Reply With Quote
Old 22-12-2014, 18:48   #93
Marine Service Provider
 
Maine Sail's Avatar

Join Date: Jan 2007
Location: Maine
Boat: CS-36T - Cupecoy
Posts: 3,197
Re: Highest output alternator

Quote:
Originally Posted by typhoon View Post
Just got it all up and running last week . This is what I am getting out of my alternator at generator speeds , 1800 rpm

Regards
That is sweet! I only wish I had the room to do a direct drive or a J mount style large case....... 180A is about my upper limit with my space constraints.
__________________
Marine How To Articles
Maine Sail is offline   Reply With Quote
Old 22-12-2014, 19:27   #94
Registered User
 
ColdEH's Avatar

Join Date: Feb 2007
Location: Toronto Canada
Boat: Bristol 45.5
Posts: 848
Images: 1
Re: Highest output alternator

Quote:
Originally Posted by Maine Sail View Post
That is sweet! I only wish I had the room to do a direct drive or a J mount style large case....... 180A is about my upper limit with my space constraints.
Thanks Maine sail . I actually had to extend my engine room a little to make it fit but it all worked out just fine . Getting the lead out with your help was a bonus as we'll . Imagine trying to put 303 amps into a lead acid bank . 2 cycles on my lifepo4 bank now .

Sorry for the thread drift

Regards
ColdEH is offline   Reply With Quote
Old 22-12-2014, 19:31   #95
Marine Service Provider
 
Maine Sail's Avatar

Join Date: Jan 2007
Location: Maine
Boat: CS-36T - Cupecoy
Posts: 3,197
Re: Highest output alternator

Quote:
Originally Posted by typhoon View Post
Imagine trying to put 303 amps into a lead acid bank .

Regards
You'd hit absorption voltage in seconds....
__________________
Marine How To Articles
Maine Sail is offline   Reply With Quote
Old 22-12-2014, 19:36   #96
Registered User

Join Date: Feb 2013
Location: WY / Currently in Hayes VA on the Chesapeake
Boat: Ocean Alexander, Ocean 44
Posts: 1,149
Re: Highest Output Alternator

If one can find the room to put a a really big alternator on a small engine why not put a cut off switch on the alternator like MaineSail did. If you need power to the prop just shut down the alt. until it you have enough power to pull it. Don't some regulators also have the ability to cut the power by half?
darylat8750 is offline   Reply With Quote
Old 23-12-2014, 02:13   #97
Registered User
 
transmitterdan's Avatar

Join Date: Oct 2011
Boat: Valiant 42
Posts: 6,008
Re: Highest output alternator

Quote:
Originally Posted by rwidman View Post
See anything wrong with the term "knots per hour"?

I think if you wand to discuss technical stuff and make any sense of it you have to understand and use the technical terms correctly.
AH per day is perfectly correct. Just as nautical miles per day is correct.
transmitterdan is offline   Reply With Quote
Old 23-12-2014, 05:26   #98
mrm
Registered User

Join Date: Feb 2011
Location: Poland, EU
Boat: crew on Bavaria 38 Cruiser
Posts: 654
Re: Highest output alternator

Quote:
Originally Posted by rwidman View Post
See anything wrong with the term "knots per hour"?

I think if you wand to discuss technical stuff and make any sense of it you have to understand and use the technical terms correctly.
He does, you don't. Sorry for being blunt.

Some light reading:
What is ampere hour (Ah or amp hour)? - Definition from WhatIs.com
Battery ratings : Batteries And Power Systems - Electronics Textbook
Frequently Asked Questions (FAQ) - DC Battery Specialists

As a side note: a more appropriate unit to discuss energy consumption is a Watt-hour, but substituting Ampere-hours (while keeping in mind some simplifications like assumption of a constant voltage and forgetting inefficiencies in the system) is often acceptable in this sort of discussions.

@Mods: apologies if I sound harsh, but shouldn't this sort of techno-nonsense be avoided on quality forums?
mrm is offline   Reply With Quote
Old 23-12-2014, 05:52   #99
Registered User

Join Date: Jun 2010
Location: Now limited to seasonal NE sailing
Boat: PT-11
Posts: 1,541
Re: Highest output alternator

Quote:
Originally Posted by typhoon View Post
Just got it all up and running last week . This is what I am getting out of my alternator at generator speeds , 1800 rpm

Regards
Neat! How about more details on your installation including pics?
SVNeko is offline   Reply With Quote
Old 23-12-2014, 07:31   #100
Marine Service Provider
 
mitiempo's Avatar

Join Date: Sep 2008
Location: Victoria B.C.
Boat: Wauquiez Centurion 32
Posts: 2,874
Re: Highest Output Alternator

Quote:
Originally Posted by Nicholson58 View Post
26 HP is not going to drive a huge alternator. Figure out what drag you can really tolerate. You can find the conversions for watts - HP. Remember to account for the inefficiency of the belts, alternator, engine etc. These are real numbers.
25 amps of alternator output uses about 1 hp
mitiempo is offline   Reply With Quote
Old 23-12-2014, 08:40   #101
Moderator Emeritus
 
a64pilot's Avatar

Cruisers Forum Supporter

Join Date: Oct 2013
Location: Jacksonville/ out cruising
Boat: Island Packet 38
Posts: 31,351
Re: Highest output alternator

Quote:
Originally Posted by mrm View Post
As a side note: a more appropriate unit to discuss energy consumption is a Watt-hour, but substituting Ampere-hours (while keeping in mind some simplifications like assumption of a constant voltage and forgetting inefficiencies in the system) is often acceptable in this sort of discussions.

I wish we would dump this whole Amp thing and use Watts, as the amount of power an Amp is, is dependent on voltage, whereas a Watt, is a Watt.
There is a significant difference with how much power an Amp is even between 12V and 14V
a64pilot is offline   Reply With Quote
Old 23-12-2014, 09:13   #102
mrm
Registered User

Join Date: Feb 2011
Location: Poland, EU
Boat: crew on Bavaria 38 Cruiser
Posts: 654
Re: Highest output alternator

Quote:
Originally Posted by a64pilot View Post
I wish we would dump this whole Amp thing and use Watts, as the amount of power an Amp is, is dependent on voltage, whereas a Watt, is a Watt.
There is a significant difference with how much power an Amp is even between 12V and 14V
Well, me too. But you see how it is...
mrm is offline   Reply With Quote
Old 23-12-2014, 09:16   #103
Registered User
 
GILow's Avatar

Join Date: Sep 2008
Location: On the boat, somewhere in Australia.
Boat: Swanson 42 & Kelly Peterson 44
Posts: 9,126
Re: Highest Output Alternator

Quote:
Originally Posted by rwidman View Post
You need to understand a little more about electricity. By definition, an amp hour (AH) is an amp of current flowing for one hour. An amp flowing for 24 hours (a day) would be 24 amp hours. Two amps flowing for 24 hours would be 48 amp hours, etc. It doesn't make sense to say "50 Ah a day".

The current consumed by your AP is the amount of current consumed by the AP multiplied by the hours used. If it draws two amps and runs eight hours, it has consumed 16 amps.
Err... no, Joefish is correct. Actually one of the very few who use the terminology correctly too. It's refreshing to see, more people seem to get that one wrong than right. Go JoeFish.

Matt
__________________
Refitting… again.
GILow is offline   Reply With Quote
Old 23-12-2014, 09:25   #104
Marine Service Provider
 
SV THIRD DAY's Avatar

Cruisers Forum Supporter

Join Date: Aug 2006
Location: La Paz, Mexico
Boat: 1978 Hudson Force 50 Ketch
Posts: 3,920
Re: Highest output alternator

Quote:
Originally Posted by a64pilot View Post
I wish we would dump this whole Amp thing and use Watts, as the amount of power an Amp is, is dependent on voltage, whereas a Watt, is a Watt.
There is a significant difference with how much power an Amp is even between 12V and 14V

Amen...Amen....and AMEN!
In my warped view of the world, manufactures should give all the data, Amps, Watts and what voltage, etc. Why don't they? Well take wind generators for example.

They LOVE to give you nice graphs showing lots of data that is meaningless to you! That way you have a really hard time doing two things:
1. Accurately comparing their unit to the competition
and
2. Knowing that their output claims are (and excuse the language) full of **** since the data they are giving you is damn near meaningless to what you will actually see on your boat.

So the bottom line...the more worthless the data manufactures can give you...the more they can BS you. Call me jaded, but why else would a marine wind turbine give wind speed in units worthless and averaged like m/s? Why else give the Amps produced at 12v...when at 12v NONE of the power would go into your battery bank to start with...AHHHH..they do it to...well....I'll say it LIE and overstate what you will see in real life. THEN they will only really explain it to you after the fact when you call up and complain that you are seeing 20% less power produced than their graph at 12v..."oh ya" they will say, "that's normal because you are charging at 13.5v"...
__________________
Rich Boren
Cruise RO & Schenker Water Makers
Technautics CoolBlue Refrigeration
SV THIRD DAY is offline   Reply With Quote
Old 23-12-2014, 22:41   #105
Marine Service Provider
 
mitiempo's Avatar

Join Date: Sep 2008
Location: Victoria B.C.
Boat: Wauquiez Centurion 32
Posts: 2,874
Re: Highest output alternator

Quote:
Originally Posted by SV THIRD DAY View Post
.... "that's normal because you are charging at 13.5v"...
Worse yet, floating at 13.5, charging at 14.4
mitiempo 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
high output alternator on 3YM30 Yanmar? c.spots Engines and Propulsion Systems 13 01-04-2012 14:53
Alternator and Tach Output Issue harbin2 Electrical: Batteries, Generators & Solar 2 04-05-2010 23:16
Alternator Output Amps captain465 Electrical: Batteries, Generators & Solar 1 13-04-2010 11:40

Advertise Here


All times are GMT -7. The time now is 06:00.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2024, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2024, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.