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: 1,747

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

Little Boy Blue - '05 Toyota Echo
90 day: 33.35 mpg (US)

BlueZ - '19 Nissan 370Z Sport
90 day: 17.19 mpg (US)
Thanks: 75
Thanked 576 Times in 426 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: 12,762

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: 1,585
Thanked 3,555 Times in 2,218 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: New Zealand
Posts: 5,005

ND Miata - '15 Mazda MX-5 Special Package
90 day: 42.54 mpg (US)
Thanks: 2,866
Thanked 2,501 Times in 1,547 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)
Volvo-driving MachYeen
 
Fingie's Avatar
 
Join Date: Jan 2015
Location: Finland
Posts: 788

Neo Volvo - '98 Volvo S70 10V
90 day: 24.98 mpg (US)
Thanks: 298
Thanked 82 Times in 68 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.



With Volvo to Valhalla and back!
  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: 1,747

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

Little Boy Blue - '05 Toyota Echo
90 day: 33.35 mpg (US)

BlueZ - '19 Nissan 370Z Sport
90 day: 17.19 mpg (US)
Thanks: 75
Thanked 576 Times in 426 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: 313

Metric - '94 Honda Magna 250
Motorcycle
90 day: 69.83 mpg (US)

RedCelica - '94 Toyota Celica ZR
90 day: 35.97 mpg (US)

i30 - '12 Hyundai i30 Elite
90 day: 39.84 mpg (US)

i30-22 - '12 Hyundai i30 Elite
90 day: 39.22 mpg (US)
Thanks: 23
Thanked 73 Times in 45 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: 57

Smokey - '13 Chevrolet Cruze Eco
Thanks: 3
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: Tampa, FL
Posts: 1,745

Volt, gas only - '12 Chevrolet Volt Premium
90 day: 38.02 mpg (US)

Volt, electric only - '12 Chevrolet Volt Premium
90 day: 132.26 mpg (US)

Yukon Denali Hybrid - '12 GMC Yukon Denali Hybrid
90 day: 21.48 mpg (US)
Thanks: 206
Thanked 420 Times in 302 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 - 2024, vBulletin Solutions Inc.
Content Relevant URLs by vBSEO 3.5.2
All content copyright EcoModder.com