EV Conversion 101

Jesse Tufts, P.Eng.

EV 101 Overview

● The Electric Japanese Mini Truck

● Safety

● Why DIY EVs? Why Not?

● DIY EV Expectations

● EV Components

● Range and Performance Estimation

● Example build

● Questions

The Electric Japanese Mini Truck

● 1992 Daihatsu Hijet Jumbo Cab

● Joint project with John Storey Bishoff

The Electric Japanese Mini Truck

● Then

● 660cc 3 cylinder gas motor, about 45hp● 4wd, 5 speed transmission● 7 L/100km fuel economy (42mpg)

● Now

● 45hp three phase AC motor● 7.6kWh lithium battery pack● 60 km max city range● 85 km/hr top speed

The Electric Japanese Mini Truck

● Joint project, shared use truck

● Started February 2010

● Licensed in Spring 2012

● 1000 + hours and counting!

● $14,000 total cost including the truck

● $0.01/km electricity cost to drive

● Very fun to drive! Great for hauling stuff

The Electric Japanese Mini Truck

Safety Disclaimer!

● DIY EVs can be dangerous

● Fire ● Electrocution● Crush injuries, you name it!

● 0.2A across your heart can kill you

● EV batteries can often provide >1000A!

● High voltage increases shock potential

● Wear gloves when doing any wiring and don't become part of a circuit!

● Keep yourself and others around you safe

Why DIY Conversion?

● Potentially cheaper than Production EVs

● More vehicle selection

● Vehicle confguration is only limited by your imagination (and your wallet)

● High performance potential

● Satisfying hobby, with a conscience!

● The more people who see EVs as viable the more they will grow

Why Not DIY Conversion?

● Potentially more expensive than Production EVs

● Can be time consuming to convert

● Will you actually fnish this project?

● Vehicle reliability is limited by your skill

● Low performance potential

● Can be technically diffcult

● Like any DIY project there is potential for safety hazards!

Great Expectations

● Vehicle Type

● Range

● Performance

● Budget

● Tools, Facilities and Skills

Vehicle Type1. How many passengers?

● Any kids on the way?

2. How much cargo?

● Do you need to haul more than groceries?

3. What type of driving?

● City vs. Highway

4. Has it been done before?

5. What do you want to drive?

● Do you want to invest $20,000 in a beater?

Range Expectations

1. How far do you really need to drive in a day?● EVs are great for commuting! ● 50km = easy, lower cost● 200km = possible but getting quite expensive

2. Could you charge at work?

3. Longest daily drive has to be less than 80% of your maximum range!

Performance

1. Top speed

● Aerodynamics● Gearing● Max motor RPM● Power

2. Acceleration

● Weight● Gearing● Torque● You want 0.5G min off the line!

Budget

● What's the maximum you're comfortable spending on this project?

● Donor cost vs. parts cost; is the vehicle worth spending a lot of money on?

● Can you meet your range and performance expectations with your selected donor vehicle and budget?

● Can you sell parts removed from the donor?

● Could you share the project with a friend?

Tools, Facilities and Skills

● Tools you'll need● Full set of typical mechanics and fabrication tools● Voltmeter, Electrical crimpers and wire stripper

● Tools that will be good to have or borrow● Welder, drill press, band saw● Engine hoist

● You'll need an enclosed garage with good lighting and a heater

● Skills● Can you do basic car maintenance?● Do you have a basic knowledge of electricity and wiring?● Do you have access to a friend who can lend a hand?

EV Components

● Motors

● Adapters and drivetrain

● Controllers

● Batteries

● Battery Management Systems

● Chargers

● Auxiliaries

● DC-DC converter● Vacuum Pump● Power Steering● Heater

AC Motors

● Smooth power and control, easy reversing

● No maintenance, high effciency

● Full torque regenerative braking

● Limited options, DIY versions are less powerful and more expensive than DC motors

● One main brand for DIY, HPEVS motors with Curtis AC controllers

DC Motors● Very high torque and power potential!

● Lots of size and brand options, less expensive than AC for a given power output

● Most types can not provide regenerative braking

● Brushes require some regular maintenance

● Brands include NetGain Motors, Advanced DC, D&D Motors, Kostov

Adapters and Drivetrain

● Adapters

● Attach the motor to the transmission input shaft

● Can be purchased or custom machined

● But, alignment is critical!● Drivetrain

● Standard transmission vs. direct drive

● 4wd can work, but expect less range

Motor Controllers● Higher Amps = Higher Torque

● AC

● Curtis 650A, 60 - 130V max● 75kw max power ● PC programable

● DC

● Evnetics Soliton Jr. - 600A, 9-340V max ● Soliton 1 – 1000A, 9-340V max ● Soliton Shiva – 3000A, 425v, 1.2MW!● PC programable, liquid cooled ● Other brands include Curtis, Netgain

Controls, Zilla

Batteries

● Typical Pack Voltage 96V-144V

● Lead Acid

● Heavy● Low effciency (60%)● Low usable capacity ● Wear out quickly (500 charge cycles)● Some types need maintenance● Cheap, easy to implement● Work well for lawn tractor or quad

conversions

BatteriesLithium Iron Phosphate

● Best chemistry for DIY conversions

● 1/3 the weight for double the usable capacity of lead!

● Effciency from 88%-95%● >1500 charge cycles if you

typically discharge to 80% DOD.● 3.2V/cell● Popular brands; CALB, Winston,

Sinopoly, Headway

Batteries● Lithium Iron Phosphate

● Don't Overcharge!● Don't Over Discharge!● Don't charge below freezing● Safe to use at -30 but

performance is poor! ● Highly recommended to use a

BMS (Battery Management System)

Battery Management Systems

● Monitor individual cells to prevent overcharging

● Bleed energy off high cells to balance the pack

● Provide warnings to prevent over discharging

● Helps diagnose a weak or defective cell

Battery Chargers

● Start under $500 for a simple 1.5 kW charger

● Up to 12 kW chargers available

● Small packs can charge off 120 V but larger packs need a 240 V charger

● Popular brands include Elcon, Manzanita Micro, Zivan, DeltaQ

Auxiliary Components

● Large vehicles need power brakes and power steering

● Electric vacuum pump for power brakes● Electric hydraulic pump for power steering

● DC-DC converter provides 12 V to power your vehicle's systems

● Electric Heat

● Use a ceramic heater core, 3000 W minimum● Heated seats only draw 60 W each! Add on kits

are available● Potential to preheat your vehicle while it's

plugged in

Fitting it All Together

Performance Estimation

● You want 0.5G acceleration!

● If you could maintain 0.5G acceleration up to 100km/hr you would get there in 5.7 sec!

● Motor torque x gear ratio = wheel torque

● Wheel torque ÷ tire radius = forward thrust

● Forward thrust ÷ vehicle weight = acceleration in Gs

● At what speed does the motor torque decrease?

● Use this to size your motor and controller

Estimating Range and Sizing the Pack

● Gas Car Effciency:● Only 14-16% in the city!● 20-26% on the highway

● Gasoline energy content = 9.63 kWh/L

● Electric car effciency: 80-90% !

● Use this to estimate the electrical energy needed to drive an EV a given distance

● Size the pack or estimate range with this value

Example Build: Toyota Echo Hatchback

● Pro's

● Lightweight – 2080 lbs● Aerodynamic – 0.29 drag

coeffcient● 4 doors● Inexpensive to buy used● Reasonably modern● Simple reliable car

● Cons

● Not terribly exciting! Yet....

Vehicle Type

1. How many passengers? (4)

● Any (more) kids on the way? (Not Yet)

2. How much cargo? (Just Groceries)

● I can use the mini truck for larger cargo

3. What type of driving? (City)

4. Has it been done before? (Yes!)

5. What do you want to drive?

● A Tesla Model S.....

Range Expectations

1. How far do you really need to drive in a day?● Spruce Grove and back safely = 60 km highway

2. Could you charge at work? (Potentially)

3. Longest daily drive has to be less than 80% of your maximum range!

● No problem, typical day <40 km

Performance

1. Top speed (120 km/hr)

● Aerodynamics (good)● Gearing (5 spd manual)● Max motor RPM (6500)● Power (105 hp original)

2. Acceleration

● Weight (2080 lbs original)● Gearing (5 spd manual)● Torque (electric will have more than stock!)● 0.5G off the line acceleration? We'll see...

Budget

● What's the maximum you're comfortable spending on this project? ($20,000 including the car)

● Donor cost vs. parts cost; is the vehicle worth spending a lot of money on? (Yes)

● Can you meet your range and performance expectations with your selected donor vehicle and budget? (We'll See!)

● Can you sell parts removed from the donor? (Yes)

● Could you share the project with a friend? (Possibly)

EV Components

● Motors – AC50

● Adapters and drivetrain – From CanEV, standard trans FWD

● Controller – Curtis 1238R

● Batteries – 36 x 100 Ah Sinopoly

● Battery Management System – Mini BMS

● Chargers – 1.5 kW Elcon

● Auxiliaries● DC-DC converter – 30 A● Vacuum Pump - yes● Power Steering – manual steering available● Heater – 3 kW min + add on heated seats!

Performance Estimation

● AC 50 Motor torque = 110 ft lbs from 0-4000 rpm

● 110 ft lbs x 12.5:1 gear ratio in 1st = 1375 ft lbs wheel torque

● 1375 ft lbs x 12”/11.5” tire radius = 1437 lbs thrust

● 2200 lb estimated car weight

● 1st gear = 0.65G up to 35 km/hr (4000 rpm)

● 2nd gear = 0.35G up to 65 km/hr (4000 rpm)

● Potential 2 sec to 50 km/hr!

● Zippy performance in the city: Check!

Range Estimation

● Pack Size = 36 x 100 Ah Sinopoly

● 115 V x 100 Ah = 11.5 kWh pack size

● City fuel economy = 6.7 L/100 km city

● 6.7 L/100 km x 9.63 kWh/L = 0.645 kWh/km

= Energy burned

● 0.645 Wh/km x 15% (city effciency) = 0.097 kWh/km

= Mechanical energy needed

● 0.097 kWh/km ÷ 80% (EV effciency) = 0.121 kWh/km

= Electrical energy needed

● 11.5 kWh ÷ 0.121 kWh/km = 95 km max city range ● 75 km safe city range, 60 km safe highway range

Cost Estimate

● AC 50 Motor / Curtis 1238R Controller

● $4,300● Motor Adapter

● $850● 36 x 100Ah Sinopoly Cells

● $5,000● Battery Management System

● $600● 1.5 kW Charger

● $400● Accessories (DC-DC, Vacuum Pump, Instrumentation, Wiring,

Metal work, etc.)

● $1,500● Total = $12,650, Typical used Echo - $5,000

● Value of the EV grin you'll have after your frst drive?

Priceless!

Cost Estimate

● Check out my blog

● Links to useful EV websites ● This presentation in PDF format.

www.jessetufts.wordpress.com

Resources

Questions?