EcoModder Forum Ideas for my first EV.

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 10-19-2015, 07:21 PM #1 (permalink) EcoModding Lurker   Join Date: Oct 2015 Location: Tijuana Mex. Posts: 7 Thanks: 0 Thanked 0 Times in 0 Posts Ideas for my first EV. Hi. My name is Alex. I'm in the process of building my first ev. So i have a couple of ideas for those of you who have do e something similar please feel free to shime in. My donor car is a 1991 mexican build vw beetle. Here is one of my crazy ideas. I want to extend the range of the battery pack or bank. Since a gasoline engine is less efective in stop and go traffic. I decided to take a look at the gearing in the transmission to try and take some load off the electric motor and in theory extend the range. So since i have been a vw nut for many years. I would try to explain my best. 1st gear ratio is 3.8 to 1 2nd gear ratio is 2.06 to 1 3rd gear ratio is 1.32 to 1 4th gear ratio is .89 to 1 Ring and pinion is 4.37 to 1 So what this means is that on 1st gear you need 3.88 turns of the engine to do one complete turn of 1st gear only. And to get one turn at the wheels you'll need 16.60 turns of the engine or electric motor. You may be wondering how i ended up whit this number. Is real easy. Just multiply the gear ratio by the ring and pinion ratio. 1st gear 3.8x4.37=16.6 turns to 1 at the wheels 2nd gear 2.06x4.37=9.00 turns to 1 ar the wheels. 3rd gear 1.32x4.37=5.76 turns to 1 at the wheels 4th gear .89x4.37=3.88 turns to 1 at the wheel. So my idea consists in adding 1.26 to 1 reduction gear boxes at the wheels like the ones used in early vw buses to relieve stress or load on the electric motor. 1st gear on reduction boxes 3.80x4.37x1.26=20.92. So in theory instead of the electric motor turning 16 times under regular load to get 1 turn at he wheels. It will require 20.92 turns under less load to get one turn at the wheels. Second crazy idea is to get one electric motor that has shaft's on both end's The idea is to use one of those shaft's to powe 1 12v alternator To keep the main accesorie battery fully charged while driving. And 2 or 3 36v marine alternators to try to extend the range. .
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 10-19-2015, 10:30 PM #2 (permalink) Master EcoModder     Join Date: Jan 2008 Location: Western Wisconsin Posts: 3,903 honda cb125 - '74 Honda CB 125 S1 90 day: 79.71 mpg (US) green wedge - '81 Commuter Vehicles Inc. Commuti-Car Blue VX - '93 Honda Civic VX Thanks: 867 Thanked 433 Times in 353 Posts Skip the alternator all together, get a dc to dc converter to take care of your 12v needs. Then the question is, are you building a hybrid, or an EV? Your stock gearing should be perfect for a EV as the the stock VW engine maxed out at around 4,500rpm
 10-19-2015, 10:37 PM #3 (permalink) EcoModding Lurker   Join Date: Oct 2015 Location: Tijuana Mex. Posts: 7 Thanks: 0 Thanked 0 Times in 0 Posts Is gonna be electric. The point of using 2 36 volt alternators is to charge the battery pack while the electic motor is running so i culd extend the range.
 10-19-2015, 11:05 PM #4 (permalink) (:     Join Date: Jan 2008 Location: up north Posts: 12,752 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: 1,581 Thanked 3,535 Times in 2,209 Posts This isn't going to end well. __________________
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 10-19-2015, 11:17 PM #5 (permalink) EcoModding Lurker   Join Date: Oct 2015 Location: Tijuana Mex. Posts: 7 Thanks: 0 Thanked 0 Times in 0 Posts How come?
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 10-20-2015, 12:35 PM #7 (permalink) EcoModding Lurker   Join Date: Oct 2015 Location: Tijuana Mex. Posts: 7 Thanks: 0 Thanked 0 Times in 0 Posts the alternator setup is to generate enough juice so i dont drain the battery to quikly. not to power the dc motor Last edited by Alex77tj; 10-20-2015 at 12:40 PM..
 10-20-2015, 12:48 PM #8 (permalink) EcoModding Lurker   Join Date: Oct 2015 Location: Tijuana Mex. Posts: 7 Thanks: 0 Thanked 0 Times in 0 Posts also what reduces the life of a battery is the amount of times you drain them
 10-20-2015, 12:50 PM #9 (permalink) EcoModding Lurker   Join Date: Oct 2015 Location: Tijuana Mex. Posts: 7 Thanks: 0 Thanked 0 Times in 0 Posts High Output Alternators High Output Alternators manufactured in the USA by ZENA, Incorporated
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Quote:
 Originally Posted by Alex77tj the alternator setup is to generate enough juice so i dont drain the battery to quikly. not to power the dc motor
You take energy you take out of the battery to run the car. Say it takes 30 HP to run your car at 55 mph (which should be close)

If you run an alternator as well, the power it 'generates' is less than the extra power you use. Say the high output alternator 'uses' another 5 HP OUT of your batteries. elhigh was trying to explain that you will only GET BACK 3.5 HP worth of power to put back into your batteries.

The Controller on your car, that takes the accelerator input and puts out power to your motor, ramps the power up and down to get the speed you want to drive.

I can only think of one way that your configuration of using an alternator to 'put back' energy into the battery will sorta work - if you have NO controller at all, on a DC motor that you just TURN ON (no throttle ramp) and you use the alternators to load the motor heavily so that it goes slower. This does not work well on a series DC motor (it has more torque as it slows down) and it is horribly inefficient (reference elhigh's explanation of the alternator efficiency) as well as kinda dangerous (it's easy to have a contactor fail closed when you are switching such high currents).

Every time you take energy and convert it - mechanical to electrical, chemical to electrical, etc - there are losses. Most of it shows up as heat.

You posted your ideas and asked for feedback. You have received the feedback. It is your choice to listen to it or not. In my opinion, you will not convince more experienced people that you are right.

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