Go Back   EcoModder Forum > EcoModding > DIY / How-to
Register Now
 Register Now
 

Reply  Post New Thread
 
Submit Tools LinkBack Thread Tools
Old 05-10-2018, 10:49 AM   #1 (permalink)
EcoModding Lurker
 
Join Date: Oct 2017
Location: Virgina
Posts: 19
Thanks: 3
Thanked 1 Time in 1 Post
To reduce amps from Alternator

I am having a Mitsubishi 4DR5 Alternator 12V 50A. I want to reduce the output around 30 Amps.

  Reply With Quote
Alt Today
Popular topics

Other popular topics in this forum...

   
Old 05-10-2018, 11:09 AM   #2 (permalink)
Master EcoModder
 
Stubby79's Avatar
 
Join Date: Sep 2012
Location: Victoria, BC
Posts: 1,093

'91 Miata - '91 Mazda Miata
90 day: 24.67 mpg (US)

'86 Fiero GT - '86 Pontiac Fiero GT

Purple Penny Pincher - '95 Pontiac Firefly Base
90 day: 43.68 mpg (US)

Jett-Black - '01 Volkswagen Jetta
90 day: 39.32 mpg (US)

Firefly EV - '98 Pontiac Firefly EV
90 day: 107.65 mpg (US)

Little Boy Blue - '05 Toyota Echo
90 day: 32.25 mpg (US)
Thanks: 40
Thanked 305 Times in 229 Posts
It doesn't put out it's rated output all the time, only if there's enough of a load on it. It tries to maintain a steady voltage, up to when it hits it's limit.

Your options are:
Reduce your electrical load as much as you can.
Replace the alt with a smaller alternator.
Rewind your alternator to reduce output.
Change the alternator pulley to potentially reduce output.
Trick your alt in to lowering it's output voltage.
Add some "fancy" current-limiting circuitry.
Remove the alternator altogether.

Or any combination of the above.
__________________

  Reply With Quote
Old 05-10-2018, 12:03 PM   #3 (permalink)
(:
 
Frank Lee's Avatar
 
Join Date: Jan 2008
Location: up north
Posts: 12,235

Blue - '93 Ford Tempo
Last 3: 27.29 mpg (US)

F150 - '94 Ford F150 XLT 4x4
90 day: 18.5 mpg (US)

Sport Coupe - '92 Ford Tempo GL
Last 3: 69.62 mpg (US)

ShWing! - '82 honda gold wing Interstate
90 day: 33.65 mpg (US)

Moon Unit - '98 Mercury Sable LX Wagon
90 day: 21.24 mpg (US)
Thanks: 1,415
Thanked 3,057 Times in 1,949 Posts
I slowed mine way down. It has to draw less HP but I can't prove it. Works great. Hardly cost anything to do.

http://ecomodder.com/forum/showthrea...ork-20558.html

P.S. F U Botophucket!
__________________



Last edited by Frank Lee; 05-10-2018 at 12:14 PM..
  Reply With Quote
Old 05-10-2018, 01:53 PM   #4 (permalink)
Master EcoModder
 
Ecky's Avatar
 
Join Date: Dec 2011
Location: Vermont
Posts: 2,659

Gaptooth - '00 Honda Insight
Team Honda
Gen-1 Insights
90 day: 70.92 mpg (US)

Such Fit - '07 Honda Fit Sport
90 day: 41.27 mpg (US)

Velomobile - '13 Sun Seeker EZ-TAD SX
Last 3: 2142.86 mpg (US)
Thanks: 909
Thanked 1,026 Times in 648 Posts
As Stubby says, if there's no load it should have very little resistance. I'm not sure what benefits there would be to lowering its RPM, unless perhaps it's more efficient at one RPM than another.
  Reply With Quote
Old 05-10-2018, 01:59 PM   #5 (permalink)
Renault owner
 
Fingie's Avatar
 
Join Date: Jan 2015
Location: Finland
Posts: 780

Neo Volvo - '98 Volvo S70
Thanks: 297
Thanked 80 Times in 67 Posts
id just invest in a bigger pulley so your alt turns slower.
__________________
If you don't make any mistakes in your life,
life itself will be a f*ckup.



it's not your fault, Renault
  Reply With Quote
Old 05-10-2018, 02:15 PM   #6 (permalink)
Master EcoModder
 
Stubby79's Avatar
 
Join Date: Sep 2012
Location: Victoria, BC
Posts: 1,093

'91 Miata - '91 Mazda Miata
90 day: 24.67 mpg (US)

'86 Fiero GT - '86 Pontiac Fiero GT

Purple Penny Pincher - '95 Pontiac Firefly Base
90 day: 43.68 mpg (US)

Jett-Black - '01 Volkswagen Jetta
90 day: 39.32 mpg (US)

Firefly EV - '98 Pontiac Firefly EV
90 day: 107.65 mpg (US)

Little Boy Blue - '05 Toyota Echo
90 day: 32.25 mpg (US)
Thanks: 40
Thanked 305 Times in 229 Posts
Quote:
Originally Posted by Ecky View Post
I'm not sure what benefits there would be to lowering its RPM, unless perhaps it's more efficient at one RPM than another.
It's output is limited at lower RPMs. It will try to make up for it by boosting the field voltage, but it will hit a wall/limit and not be able to output any more without spinning faster. (as shown by cars with small alternators that can barely keep the voltage up at idle with a decent load put on)

Rather like an engine, it will have maximum efficiency when kept close to it's peak output. Peak output for a given RPM will always be better than partial at a higher RPM.

Plus, hey, they usually have fans build on/in them, so there will be a tiny bit less power "wasted" by the fan spinning slower.
__________________

  Reply With Quote
Old 05-11-2018, 02:22 AM   #7 (permalink)
Wanting more for less
 
D.O.G.'s Avatar
 
Join Date: Jan 2011
Location: New South Wales, Australia
Posts: 270

Metric - '94 Honda Magna 250
Motorcycle
90 day: 71.83 mpg (US)

RedCelica - '94 Toyota Celica ZR
90 day: 35.97 mpg (US)
Thanks: 17
Thanked 63 Times in 37 Posts
Quote:
Originally Posted by Stubby79 View Post
It's output is limited at lower RPMs. It will try to make up for it by boosting the field voltage, but it will hit a wall/limit and not be able to output any more without spinning faster. (as shown by cars with small alternators that can barely keep the voltage up at idle with a decent load put on)
Too true.
When I modded my Datsun to have a really tall overdrive, I didn't take into account the reduced engine rpm also meant reduced alternator rpm.
At 60kph, (with only 40A to start with), it couldn't keep the battery charged with lights, wipers and demister all going.
__________________



  Reply With Quote
Old 05-17-2018, 01:44 AM   #8 (permalink)
EcoModding Lurker
 
Join Date: Oct 2017
Location: Virgina
Posts: 19
Thanks: 3
Thanked 1 Time in 1 Post
Changing Pulley and warranty

Quote:
Originally Posted by Stubby79 View Post
.
Change the alternator pulley to potentially reduce output.
and
Quote:
Originally Posted by Fingie View Post
id just invest in a bigger pulley so your alt turns slower.
Changing pulley will be plain sailing for me. I think I should go for it. Does it have any impact on warranty status?
  Reply With Quote
Old 05-17-2018, 02:48 AM   #9 (permalink)
EcoModding Lurker
 
Join Date: Feb 2014
Location: Ohio
Posts: 41
Thanks: 2
Thanked 2 Times in 2 Posts
I had an idea years ago of a cvt drive for accessories. Engine speed changes yet the accessory drive stays at a consistent rpm.
  Reply With Quote
Old 05-17-2018, 11:37 AM   #10 (permalink)
Master EcoModder
 
Join Date: May 2012
Location: Indiana
Posts: 1,346

Traverse 2LT FWD - '12 Chevrolet Traverse 2LT
90 day: 21.2 mpg (US)

Volt, gas only - '12 Chevrolet Volt Premium
90 day: 42.14 mpg (US)

Volt, electric only - '12 Chevrolet Volt Premium
90 day: 132.97 mpg (US)
Thanks: 123
Thanked 288 Times in 194 Posts
Quote:
Originally Posted by Grinder74 View Post
I had an idea years ago of a cvt drive for accessories. Engine speed changes yet the accessory drive stays at a consistent rpm.
You mean, electric driven accessories?

__________________




  Reply With Quote
Reply  Post New Thread


Thread Tools




Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2018, vBulletin Solutions Inc.
Content Relevant URLs by vBSEO 3.5.2
All content copyright EcoModder.com