Resilient Design founder Grant Watson has converted a small pickup (a 1996 Chevy S10) to electric. This prototype project is the start of a venture to provide affordable electric work trucks to his community on Vancouver Island, British Columbia.
I chose this basic vehicle because it is light, affordable and has manual transmission. Electric motors do not match well with automatic trannies. Most of the components were purchased from Canadian Electric Vehicles in Nanaimo, BC. The main ones are:
- Netgain Hyper9 IS 108hp/81kW AC motor
- X1 motor controller
- Elcon UHF3300 16Amp charger
- Orion II BMS
- 30 Basen 120Ah LiFePo4 cells (12kWh, 100V nominal) purchased directly from the manufacturer.
CANEV sells an adapter kit to connect the motor to the Chevy manual 5-speed transmission. However, I designed the battery box, electronics panel and motor mount.
This post will give you a peek into some of the steps I went through to make this conversion happen.
Design
As mentioned, most of the components for this project were purchased from a single source, and CANEV is good at providing parts that work together. The main design challenge was the battery pack. In an effort to be rigorous in this, I set the goal of calculating the energy required to maintain a velocity of 100 km/h for 1 hour for a similar vehicle to the s10. This would give a range of 100 km highway, ignoring acceleration, so I only needed to consider friction and drag while cruising.
I found a study which looked at this exact thing but for a generic mid-size car. While my truck is as light as a lot of passenger cars, and actually lighter than a typical SUV, its wind resistance would be slightly higher, so I expect a bit less range than what the study found. Total power required including efficiency loss in the motor, drivetrain friction and wind resistance for the s10 travelling at 100 km/hr is roughly 15kW. Energy required to sustain that for 1 hr is 15kWh. Simple. Apologies, I’ve lost the link to the study I used. Here is a good calculation if you have the coefficient of drag and frontal cross-section of your vehicle in m2.
Armed with that approximation I then looked at what space on the truck to place the batteries. My first thought was to mount 2 boxes on either side of the driveshaft. On one side is a long narrow gas tank which would come out and on the other the exhaust pipe, also deadweight. To make a long story short I found a brand of single cell LiFePo4 batteries with an energy capacity of 120 Ah each at 3.2V. I could fit 30 of them into a box approximately 13″W x 50″L (32×124 cm) which would fit on one side of the driveshaft. Each box would give me 12kWh for a total of 24. That should give me a highway range of ~150km.
What I’ve implemented so far is one of the boxes and for simplicity it is mounted at the front of the truck bed. It remains a future project to add the 2nd pack and relocate them out of sight. I have a nice local vehicle for now.
Bench Test 1: Drive System
Once the parts where purchased, those required to integrate the battery pack, Battery Management System (BMS), motor controller and motor were wired up for a bench test. This required basic configuration of the BMS software to ensure it recognized the type of batteries and the safety parameters required. The Orion II is an extremely feature-rich BMS that provides redundant safety mechanisms, lots of sensor inputs and excellent realtime data gathering.
For the test the BMS received its 12V power supply from a small transformer because at this point I hadn’t bought the truck yet!
The image shows the configuration software for the motor controller on the laptop. The bench test enabled configuration and ‘commissioning’ of the motor. The latter is a process of tuning the feedback mechanism in the motor to ensure optimum timing and shape of the electical power signal. These modern AC motors are the result of immense R & D. Netgain claims an efficiency of over 90% in the range of 1500-7200 rpm. Compare this with 38% for an ICE engine.
Bench Test 2: Charging System
The next step was to configure components for a test of the charging system. This process had many challenges including obsolete documentation on one manufacturer’s website, a ground fault error in our house wiring which was ultimately traced to a faulty breaker in the household heat pump, which was on a separate circuit!
In the image above the heavy orange cable hooked to the edge of the bench has the charging port on the end. Its a standard J1772 receptacle.
The original 12V battery from the truck is used for this test to power the BMS. Ultimately 12V supply will be provided by the traction batteries through a DC/DC converter, with the 12V battery doing the work when not in drive mode.
You can see the battery box starting to take shape.
The problem with wiring specifically for this test is that it is temporary and has to be re-done for the final install which integrates the drive and charge sub-systems, making for more work. The advantage of wiring for charge system only for the test is that it is simpler and perhaps easier to trace problems.
Battery Enclosure
The battery box is made of 24 gauge galvanized steel, reinforced on the sides with angle bar for rigidity. The lid, also 24 gauge galvanized adds additional rigidity when secured to the box. This results in a light, solid enclosure. The ends are open for addition of a ventilation fan at one end and louvers at the other. The battery cells are arranged lengthwise in a 6 x 5 pattern. They are all in series electrically and this arrangement enables short bus bars between cells. Copper is recommended for these but I used aluminum because the resistance, measured in micro-ohms, is acceptable. Busbar cross-section is 1/4″x3/4″.
The cells are surrounded in the box by a silicon rubber mat underneath and 1″x1/2″ bars between and above, allowing good airflow horizontally through the box. In my climate, warming the batteries in cold weather is more important than cooling on hot days so a heating coil will be installed in the box.
Motor Install
Before attaching the motor to the transmission, the following steps are required:
- attach the custom adapter plate to the motor as per supplier instructions
- remove the flywheel and clutch plate from the back of the original ICE engine and mount them to the back of the adapter plate (a clutch alignment tool is essential)
That black bracket on the front of the motor comes with the kit I bought. It bolts on to my motor mount which is a 1/8″ steel plate that is welded to the main frame members on each side.
Electronics Panel Install
What can I say, this is where all the manual reading and schematic drawing comes together. Its also an art to arrange the components to minimize space and wire length.
Road Tests
Once everything is assembled and wired up, much testing and tweaking is required to get a road-worthy vehicle. For the first few weeks I was driving with my laptop running the BMS utility app, which allows me to monitor the status of the batteries, see error codes and change parameters. Todd at canev.com was very helpful during this process.
Results
I’m surprised at how smoothly the beast runs, given that I’m not an engineer or mechanic. I only use 2nd and 5th gears; 2nd to get up to about 20 km/hr then 5th can easily take over. The maximum amperage my battery pack can produce continuously is 360A, which means ~36kW of power, but I have it configured so I can do bursts of about 50kW for a few seconds. The motor can consume about 89 kW to produce its peak output of 81kW, but I don’t need that kind of power. I might wreck my drive train on this old truck.
You probably want to know what range it gets. I’m still working out some battery issues so stay tuned. I’m expecting to land in the 70-80 km range.