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This project covers the conversion of a Roketa GK25 buggy to an electric vehicle. The goal is to at least equal the existing performance of the original buggy.
The first phase of the build will use commercially available parts.
The second phase is to design and build new motor controllers, battery chargers, BMS etc from scratch to replace many of the commercial modules. I am an engineer and like to know how things work and how to build them from scratch! Also for hobbyists, Makers and Hackers out there that would rather build something from scratch and tweak to suit their needs I will be sharing this information so they have a good starting place for their projects.
Before moving to the USA I had started on another EV conversion, but had to leave it behind... 11 Years later I finally have the chance to work on one again.
This page shows the current status and final decisions for the project.
The Research page has links, sketches, power graphs, motor research etc
The Photos and Videos page has the photo gallery and video links to this and other EV projects
The Costs page shows how costly it is to do this conversion, and it is costly!
| ENGINE | Original | EV Upgrade |
| Type | 3 Cylinder, 4 stroke | 3 Phase AC induction Motor - HPEVS ACC20-06.06 Pump Motor |
| Displacement | 800cc | Curtis 1238-6501 AC induction motor controller 48-80V 550A |
| Cooling | Water -cooled | Air Cooled Fan on Motor - Heatsink and Fan on Controller (may change) |
| Max horsepower | 35.1hp/5500rpm (26.18KW) | 32.7hp/5200RPM (72V 300A) 47.6hp/4200RPM (72V 550A) |
| Max torque | 57n.m /2500-3000rpm (42.04 ft lbs) | 40.3ft-lb @0RPM 32.7 @5200RPM (72V 300A) 69.0ft-lb @0RPM 59.4 @4200RPM (72V 550A) |
| Fuel | 5.3Gal Petrol | Lithium Ion - 72V ~9000Watt/hour 18 x Nissan Leaf G2 Cells 9S2P configuration |
| Speed | Max 62.1MPH | Unknown |
| TRANSMISSION | Original | EV Upgrade |
| Transmission | 4 speed plus reverse | Original 4 speed plus reverse |
| Clutch | Foot - Hydraulic | Foot switch - Simulated by Motor controller |
| CHASSIS | Original | EV Upgrade |
| Suspension | Double a-arm / independent suspension | Same but may beef up to take extra weight |
| Breaks | 4 wheel Disk breaks / Hydraulic | Same + Regenerative Breaking by accelerator and Break pressure sensor |
| Tires | Front: 25x8-12 Rear: 25x10-12 | Same |
| Weight | GW: 1036 NW: 948lbs | Unknown |
| Max load | 551.2lbs | Unknown |
HPEVS ACC20-06.06 Pump Motor was chosen for the following reasons.
Curtis 1238-6501 AC induction motor controller 48-80V 500A controller
The Nissan Leaf LiMn2O4/LiNiO2 G2 Battery cell was chosen.
Internally it is a 2p2s configuration.
https://insideevs.com/dissecting-leaf-battery-wvideo/
Used Tesla batteries would be the best option, but requires 3 x 24V modules at $1500 each to get the needed voltage so out of price range.
A battery management system is essential for charging of the battery and limiting over current and over voltage situations.
Tracking down an 18c high current BMS is not easy.
No charger has been selected at this stage of the project
26 Jan 2020
Test drive at a friends back lot - another Friend driving with his son
22 October 2020
Test drive at a the office - 0-50 then stop 1st and 2nd gear used
9 May 2019
Lot has happened since the last update....
Motor, Controller and other misc parts have arrived. Wrong Motor arrived, so had to wait a few weeks for the correct one to be assembled and shipped, but it is here now.
Vehicle has been moved to my Garage, which is insulated and has AC - essential for working in the Arizona Summer!
Transmission, old broken seats, clutch cylinder not needed lines and seriously degraded wiring harness have been removed.
Essential parts for the body have been ordered (1 drive shaft, Some steering parts and a few other misc items)
Next step is to build the adapter plate and adapter shaft so we can mount the motor to the transmission.
Misc photos below
13 Feb 19
Batteries have arrived!
Starting plan for battery box, positioning etc.
Also need to sort through then balance and condition the cells.
10 Feb 19
18 used Nissan Leaf G2 Battery packs have been ordered from ebay (Est delivery 19 Feb 19th 2019)
2 x 18 Cell 150A BMS (Battery Management system) have been ordered from Aliexpress (Est Delivery 14 March 2019)
4 Feb 19
Requested quote for Motor, Controller, Cables, Breakers etc
2 Feb 19
Removed Radiator and exhaust system. Remounted transmission to chassis and took measurements
Disassembled clutch plate to remove the spline in preparation of the adapter
Did some sketches for ideas - see photos for sketches and photos.