The "typical" conversion retains the OEM manual gearbox as a gear reduction stage between the motor and the differential. This is almost always preferable to a direct drive setup for street cars — you get a much wider performance envelope across vehicle speeds.

The $16–19k parts budget for a small car typically breaks down roughly as: motor + controller ($3–5k), battery pack ($6–9k), charger + BMS ($1–2k), adapter plate + motor mounts ($1–2k), cabling + contactors + fusing ($1–2k), and miscellaneous (DC-DC converter, charging inlet, instrumentation) (~$1k).

Heavier builds require higher-voltage systems (144V+) and often dual motors, which pushes the controller and battery costs up significantly. A large pickup targeting 100+ miles of range with decent performance can easily approach $35–40k in components alone before any shop labor.

The battery pack is typically 40–50% of the total parts cost and the area with the most flexibility. Used Tesla modules (Model S/X) offer excellent energy density at a fraction of new cell pricing, and EV West has significant experience with these packs. The trade-off is that used modules have unknown cycle history and may require cell-level inspection.

Eliminating "environmentals" (A/C, cabin heat) on a mild-climate daily driver or weekend car can save $1,500–3,000. Manual brakes and steering on a VW Beetle or similar light car are genuinely fine — the car is light enough that the absence of vacuum or hydraulic assist isn't a safety concern.

The VW Beetle is roughly a 40–60 man-hour build for an experienced team. The VW Bus takes ~80–100 man-hours due to the added complexity of the bus frame and battery placement. More exotic builds (Porsche 911, custom frames) can run 200+ hours.

For first-time DIYers: car mechanical experience matters more than electronics experience. If you can swap a motor and aren't afraid of a multimeter, you'll do fine. Budget 2–3× the hours you think it will take for your first build.

The AC50/Hyper 9 class of motors produces approximately 65–70kW peak. The 1kW ≈ 1.34hp conversion gives you ~87–94hp at peak, but the torque curve is the real story: peak torque is available from 0 RPM, whereas a gas engine needs to build through its powerband.

A useful rule of thumb: a gas car needs ~1.4× the hp of an equivalent EV to match it in a 0–60 test. A 70kW (~95hp) EV will typically run with a 130–140hp naturally aspirated gas car.

For 300hp+ targets: aim for 30% less kW than the equivalent gas rating. So 200kW (~268hp) gets you into the 280–300hp gas-equivalent territory. At this level, the battery pack to sustain that power (and the cooling system to go with it) becomes the significant cost driver.

The standard rule of thumb for a lightweight classic car is approximately 300Wh/mile at moderate speeds. Using that:

So a 30kWh pack ≈ 100 miles. A 24kWh pack (the average EV West customer purchase) ≈ 80 miles.

Real-world modifiers: cold weather reduces capacity 15–30%. Highway speeds above 65mph increase consumption significantly. Aggressive acceleration on repeated short trips can cut range 20%+. Conversely, flat terrain and mild temps can push you above the rule-of-thumb number.

Top speed is primarily a voltage function. Higher system voltage = higher RPM ceiling = higher top speed before back-EMF limits the motor. Range and speed are always in tension — the faster you cruise, the more kWh/mile you burn.

Power (kW) = Voltage (V) × Current (A) ÷ 1000. This is why both voltage and amp capacity of your battery and controller matter for peak power output.

Energy density comparison: 1 gallon of gasoline contains ~33.7kWh of energy, but an ICE engine only converts ~25–30% to motion (70–75% is waste heat). An electric drivetrain converts 85–95% of stored energy to motion. So 30kWh of battery is roughly equivalent in range to ~2 gallons of gas in a comparable vehicle.

Pack voltage × amp-hour (Ah) rating = total Wh. Divide by 1000 for kWh. Example: a 96V nominal pack with 300Ah of cells = 28.8kWh.

LiFePO4 (lithium iron phosphate) cells are more cold-tolerant than NMC chemistry but still exhibit internal resistance increases below 10°C (50°F). The internal resistance increase reduces both available power (kW) and usable capacity (kWh).

Below freezing, charging LiFePO4 cells at full rate can cause lithium plating — a degradation mechanism. Most BMS systems will derate charging current automatically in cold conditions, which also extends charge time. A pack heater (PTC or glycol-loop depending on your setup) solves this and is worth including in cold-climate builds.

The weight difference is significant: a typical 30kWh lead acid pack weighs 700–900 lbs. An equivalent lithium pack (LiFePO4 or NMC) weighs 200–350 lbs. That 400–500 lb savings is roughly 15–25% of total vehicle weight for a VW Beetle — a massive handling and efficiency improvement.

LiFePO4 (lithium iron phosphate) is the preferred chemistry for EV conversions due to its thermal stability, long cycle life (2,000–4,000 cycles to 80% capacity), and lower cost per kWh than NMC. EV West uses LiFePO4 cells in most builds. Tesla modules use NMC and offer higher energy density at the cost of more demanding thermal management requirements.

Energy density comparison: lead acid ~30–50 Wh/kg vs LiFePO4 ~120–160 Wh/kg vs Tesla NMC modules ~250–260 Wh/kg. The Tesla module advantage is significant for packaging in tight spaces.

Beyond voltage, measure the internal impedance (AC resistance) of each cell using a cell analyzer or impedance meter. Record both values in a spreadsheet. Cell voltage is actually a less reliable health indicator at 50% SOC — impedance variance is a better predictor of cell longevity and balance behavior.

Sort cells by impedance and set aside the outliers (highest variance from median). These are your spare cells — don't include them in the main pack, but keep them from the same batch for future replacement. Most customers buy 2–4 extra cells for exactly this purpose.

On top vs. bottom balance: EV West uses a bottom balance approach for initial pack commissioning — this effectively performs a capacity test at the top of charge and identifies any short-capacity cells before they cause problems. A top balance is the safer long-term operating method; bottom balance is used as an initial screening tool.

Pack design has two independent variables: voltage (determines performance ceiling) and capacity in kWh (determines range). These are set by how you wire the cells — series connections increase voltage, parallel connections increase capacity.

System voltage also determines motor and controller selection — most street builds run 72V, 96V, 120V, or 144V nominal. Higher voltage = higher top speed potential and better motor efficiency at highway speeds.

Example: 32s2p configuration with 3.2V/100Ah cells = 102.4V × 200Ah = 20.48kWh.

The on-board charger (OBC) is a PFC (power factor corrected) AC-to-DC converter and is sometimes called a "rectifier." It communicates with the BMS via CAN bus (on modern builds) to manage charge termination — stopping at the correct voltage and tapering current as cells approach full charge (CC/CV charging profile).

J1772 Level 2 stations deliver up to 80A at 240VAC = 19.2kW maximum. Most aftermarket chargers are 3.3kW, 6.6kW, or 10kW rated. Running dual 5kW chargers = 10kW total, approaching the practical limit on a 240V/50A circuit. Beyond 10kW requires a dedicated 60A+ circuit with appropriate panel capacity.

On-board charger voltage range must match your pack voltage. A charger rated to 116.4V (for a 96V LiFePO4 pack at full charge) will not work on a 150V pack. Verify compatibility at time of purchase.

A more useful metric than total charge time is miles of range per hour of charging. At 5kW and 300Wh/mi consumption: 5000W ÷ 300Wh/mi = ~16.7 miles per hour of charge. For most commuters, plugging in overnight at even 3.3kW adds 80+ miles of range — more than enough for daily use.

Level 3 DC fast charging (CCS/CHAdeMO) for aftermarket EVs is an evolving area. Several manufacturers now offer aftermarket DC fast charge systems, but pack voltage compatibility and BMS integration complexity mean this remains an advanced-build option. Standard street builds don't need it.

Motor: Converts electrical energy to mechanical torque. AC induction (most common for street builds) or PMAC/PMSM (permanent magnet — higher efficiency, better at low RPM). EV West favors the NetGain Hyper 9 (AC induction) and Tesla LDU (PMAC) for most builds.

Controller (inverter): Converts DC battery power to 3-phase AC for the motor. Controls torque and speed. Must be matched to motor and pack voltage. The Hyper 9 controller and Tesla LDU controller are purpose-matched to their respective motors.

BMS: Monitors and balances individual cell voltages, manages charge/discharge limits, provides protection against over-voltage, under-voltage, over-temp, and over-current. Non-negotiable on a lithium build — it's the safety brain of the pack.

Contactor box: High-voltage relay system that connects/disconnects the pack from the drive circuit. Includes pre-charge circuit to limit inrush current when the system first energizes. A pre-charge failure is one of the most common early-build issues.

DC-DC converter: Steps down HV bus (72–150V+) to 12V to power all conventional 12V accessories (lights, horn, radio, BMS displays) and keep the 12V battery charged. Without this, you'd drain a 12V aux battery quickly.

DC series wound motors have a favorable torque curve for drag racing — extremely high peak torque at stall, which drops off as RPM rises. This makes them quick in a straight line but inefficient at sustained highway speeds. Brush wear under high-current conditions limits continuous power ratings.

AC induction motors (Hyper 9, HPEVS AC series) have a flat continuous power curve, regenerative braking capability, and no wear items in the motor itself. The controller (inverter) does the work of commutation electronically. The trade-off is a more complex controller and higher system cost.

Tesla LDU (Large Drive Unit) is a permanent magnet AC synchronous motor — higher efficiency than induction, especially at partial loads, with exceptional peak power density. Requires the proprietary Tesla controller and supporting coolant infrastructure.

Key mechanical criteria: (1) solid unibody/frame with no structural rust, (2) known drivetrain that has good adapter plate availability, (3) under 3,500 lbs ideally — each additional 500 lbs requires approximately 30% more motor power and 15% more battery capacity for equal performance, (4) manual transmission in good condition — you're keeping it, so it matters.

Pre-conversion work worth doing: paint and bodywork (you won't want to stop the project mid-build for this), brake disc conversion, fresh wheel bearings, and any known suspension issues. The conversion process generates a lot of vibration from drilling and fitting — do bodywork first.

EV West can build kits for a wide range of vehicles. Vehicles with an established EV West kit (VW Beetle/Bus, Karmann Ghia, Porsche 911/914, etc.) have the shortest lead time and most refined installation process.

Direct drive (motor connected directly to differential without a gearbox) limits you to a single gear ratio. You optimize either for low-speed torque/acceleration OR for top speed — you can't have both. The manual gearbox solves this by giving you multiple gear ratios across the motor's torque band.

The "magic number" for a given build is the gear ratio at which the motor operates most efficiently at your target cruising speed. Finding this helps you determine whether you need an overdrive gear, which gears you'll actually use day-to-day, and how to set controller RPM limits.

DC voltage at conversion levels (72–150V+) is particularly dangerous because the body's involuntary muscle response to DC shock tends to cause grip, not release. AC shock at equivalent voltage typically causes involuntary muscle release. This makes HV DC work more hazardous than most people expect.

Essential safety components: manual service disconnect (MSD) accessible without tools, pre-charge circuit to prevent inrush damage and sparking at contactors, properly rated fusing at the pack positive terminal (closest physical point to the pack), and insulated bus bars throughout. All HV wiring should use orange-jacketed cable per EV industry convention.

Fire risk with lithium: LiFePO4 chemistry is among the safest lithium chemistries — significantly more thermally stable than NMC. Thermal runaway requires simultaneous mechanical damage + electrical abuse. Standard builds with proper BMS protection are safe. NMC (Tesla modules) requires more careful thermal management but remains safe with proper installation.