Talk me through an EV! I'm tempted to build, but no real knowledge!

[320touring]

Right,

I have a hairbrained idea that building an EV version of a car could be a fun way to get a cheap commuter- that and a decent way to use some of the scrap and guff over at my unit.

I currently have a 64 mile commute each day- taking upto 1.5hrs each way, with no option to charge at work (although I could ask nicely!)

Charging would likely be at home overnight off my domestic supply


As I understand it, I need the following

1. Vehicle to be converted (likely RWD for ease of connecting to gearbox/bigger motor/skidz!)

2. Electric Motor

3. Potentiometer

4. Batteries

5. Controller

6. Charging system

7. Regen braking setup


So I need you folks to advise me on the following points

Electric Motor

What size do I need? 70 mile range at 50+mph

I understand that its amps drawn that's the key to matching output/heat/range?

Batteries

What type?

How many Volts?

How to connect and balance?

[esoneson]

Read the sticky above: Electric Vehicle Information - Start Here

Looks like a good place to Start......

[320touring]

I've already read about the Forkenswift and Ben's car, and had a read through the direct drive EV that NachtRitter posted.

The reason I'm asking re motors and batteries is that none of the above projects have the range that I'd require, so I was looking for some pointers on what sort of spec would be needed-and whether it'd be viable (say, against building an IC car that was hyper efficient)

thanks

[Ryland]

First off, to go 130 miles per day, you are going to need a huge battery pack, say 300 amp hours at 144v if you can keep your electrical draw down to 300 watt hours per mile and my figure there gives you a small buffer so you don't over discharge your pack and destroy it right away.
Anyway, you'll need to go with lithium batteries and just the battery pack is going to cost you at least $15,000 and weigh 1,000 pounds, if you want a "cheap" battery pack that will give you that range, you'll have a lead acid pack that weighs no less then 4,600 pounds, at that point you'll for sure need a truck frame, trucks out there tend to get 500-600 watt hours per mile... so double the size of the pack and suddenly your truck isn't big enough.

You have three options that I see, take out a loan to build your EV, move closer to your job, convince your workplace to let you charge at work or find a car that burns fuel that gets good mileage.

[320touring]

Originally Posted by Ryland

First off, to go 130 miles per day, you are going to need a huge battery pack, say 300 amp hours at 144v if you can keep your electrical draw down to 300 watt hours per mile and my figure there gives you a small buffer so you don't over discharge your pack and destroy it right away.
Anyway, you'll need to go with lithium batteries and just the battery pack is going to cost you at least $15,000 and weigh 1,000 pounds, if you want a "cheap" battery pack that will give you that range, you'll have a lead acid pack that weighs no less then 4,600 pounds, at that point you'll for sure need a truck frame, trucks out there tend to get 500-600 watt hours per mile... so double the size of the pack and suddenly your truck isn't big enough.

You have three options that I see, take out a loan to build your EV, move closer to your job, convince your workplace to let you charge at work or find a car that burns fuel that gets good mileage.

Hi, thanks for the response!

My commute is only 64 miles total, so I'd only need 70 miles range. Hopefully that'd make the battery pack smaller and more affordable?

[P-hack]

Nissan Leaf 4DR HB SV | eBay

so you can get a production ev for like $17k, but even then 70 miles is iffy.

[320touring]

Originally Posted by P-hack

Nissan Leaf 4DR HB SV | eBay

so you can get a production ev for like $17k, but even then 70 miles is iffy.

I have looked at them over here- the prices are not too bad- but most have battery hire deals tied in etc that munch away at savings

[P-hack]

Oh yah, forgot about that leaf battery rental fiasco. "lets hide the costs so it looks better!" I don't even spend $100/month on gas, can't imagine spending it on battery rental for so few miles.

[Ryland]

Originally Posted by 320touring

Hi, thanks for the response!

My commute is only 64 miles total, so I'd only need 70 miles range. Hopefully that'd make the battery pack smaller and more affordable?

Yes, that will make the pack size you need about half, I would still go with lithium because needing over one ton of lead acid batteries is just insane! and lead acid batteries are not even half the cost of lithium batteries any more, so after 3-5 years when you have to replace your lead pack with another lead pack you will have spend more money on lead acid batteries, plus you'll have a poor performing EV because you were hauling around an extra ton of weight!

Sure, used lead acid batteries are an option... if you are going short distances, but if you go with used batteries figure you'll need twice as many for the same range... again that really adds up!

You asked about rear wheel drive and motor sizing, transmissions are nice because they give you a range of gear ratios to use, most people use 2nd gear only around town and 4th gear once they are up to highway speed, front wheel drive cars work great and they tend to be lighter weight cars then rear wheel drive.

As for selecting a motor, NetGain and some other motor companies tell you what size vehicle their different motors are ideal for, then compare the physical size of a motor you found used to see what it is close to and if it will work for you, I would look at motors that are 9" around or larger, 9" will be about as small as you'd want to go, using it for a long commute you are going to want to make sure you have a blower on it to keep it cool.

[Daox]

This is basically what you want:

http://ecomodder.com/forum/showthrea...nge-22955.html

He still spent $11k on batteries.