The lithium-ion battery pack is the "heart" of your Dacia Logan II electric vehicle conversion, directly determining the range, performance, and even the weight distribution of the vehicle. Choosing the right battery pack requires balancing capacity, voltage, size, and safety—while also adapting to the compact body structure of the Logan. This guide breaks down the key factors to ensure your battery pack meets your driving needs and is reliable and durable.

1. Understanding Capacity: Balancing Range and Practicality

Capacity, measured in kilowatt-hours (kWh), directly determines how far your converted Logan II can travel on a single charge. For a vehicle of this size (compact sedan, weighing approximately 1100-1300 kg), the typical battery pack capacity ranges from 20-40 kWh:

• 20 kWh battery pack: Provides approximately 100-150 km of real-world range, suitable for short daily commutes.
• 30-40 kWh battery pack: Extends the range to 150-220 km, sufficient for weekend getaways or longer commutes.

Avoid overestimating your needs—a larger capacity battery pack increases weight and cost. Calculate your average daily driving distance and add 50% as a flexible buffer (for example, if you drive 60 km daily, a 20 kWh battery pack should suffice). Remember that extreme temperatures (cold or hot) and high-speed driving will reduce range, so consider the climate conditions in your region.

2. Voltage: Matching Your Motor and Charger

Lithium-ion battery packs operate at specific voltages, and compatibility with your motor and charger is essential. Most Logan II conversions use systems ranging from 144V to 400V (common range in 2025):

• 144V battery pack (typically 40 cells in series, each at 3.6V): Pairs well with 50-70 kW motors, common in conversions focused on city driving. They are lighter and simpler in construction but may limit top speed.
• 300V-400V battery pack (e.g., 83-112 cells in series): Suitable for 70-120 kW or higher-power motors, enabling highway cruising speeds and higher efficiency. They can work with high-power chargers (11 kW and above) but require more robust wiring.

3. Physical Size and Weight Distribution

The Dacia Logan II has limited storage space, making the battery pack's size critical. Carefully measure the available areas:

• Trunk: A 20 kWh battery pack (approximately 500mm x 300mm x 200mm in size) can be placed here but will reduce cargo space.
• Under seats or floor: Custom installation in the rear footwell or under the seats can save trunk space but requires careful design to avoid compromising legroom.
• Engine compartment: Usually only suitable for small auxiliary battery packs; the main battery pack is too large to fit easily.

Weight distribution significantly impacts handling. The stock Logan is a front-wheel-drive vehicle with weight biased toward the front—placing some batteries at the rear helps balance the weight but be careful not to exceed the vehicle's total weight limit (typically 1600-1800 kg). A 30 kWh lithium-ion battery pack weighs approximately 150-220 kg; distribute its weight evenly to prevent uneven tire wear or poor handling.

4. Chemistry Type: Choosing the Right Lithium-ion Battery

Lithium-ion batteries come in various chemistries, each with its pros and cons:

Chemistry Type	Advantages	Disadvantages	Best For
LiFePO₄ (Lithium Iron Phosphate)	High safety, long lifespan (3000+ cycles), good high-temperature tolerance	Slightly heavier per kWh, lower energy density	DIY conversions, safety-first applications
NMC (Lithium Nickel Manganese Cobalt Oxide)	Higher energy density (more range per kg), widely used in OEM EVs	Lower thermal stability, requires strict thermal management	Maximum range with active cooling
LTO (Lithium Titanate)	Extremely long lifespan, fast charging, wide temperature range	Very expensive, low energy density	Specialized applications, extreme conditions

For Logan II conversions, LiFePO₄ batteries are recommended due to their durability and lower fire risk—crucial for converted vehicles without factory safety systems. If you prioritize range and can add an active cooling system, NMC batteries are also an option.

5. Safety Features: Non-Negotiable Protection Measures

Lithium-ion batteries must have built-in safety measures to prevent overheating, overcharging, or short circuits:

• Battery Management System (BMS): Monitors the voltage, temperature, and current of each cell. It balances cells (preventing overcharging) and shuts down the battery pack in emergencies. Ensure the BMS matches your battery pack's voltage and capacity.
• Thermal management: Passive cooling (heat sinks) is suitable for small-capacity battery packs, but systems of 30 kWh and above often require fans or liquid cooling to handle heat generated during charging and discharging.
• Enclosure: Fire-resistant, waterproof housing (with protection ratings like IP67) protects cells from moisture and impact. Steel or aluminum enclosures enhance durability without adding excessive weight.

Look for battery packs certified to UN38.3 standards, ensuring they have passed safety tests related to transportation and use.

6. Cell Configuration: Series and Parallel

Battery packs are built by connecting cells in series (to increase voltage) and in parallel (to increase capacity). For example, for a 30 kWh, 300V battery pack:

• Connect 83 cells in series (each at 3.6V) to reach approximately 300V total voltage.
• Connect 2-3 sets of these 83-cell series groups in parallel to increase the total capacity to 30 kWh.

7. Cost and Lifespan

The lithium-ion battery pack is the most expensive component of the conversion, with pre-assembled units priced between ¥800-1500 per kWh (approximately $110-210) in the 2025 market. A 30 kWh battery pack costs around ¥24,000 to ¥45,000, but DIY assembly using recycled cells can reduce costs by 30-40% (though it requires more effort).

Lifespan depends on chemistry and charging habits: LiFePO₄ battery packs can last 3000+ cycles (about 8-12 years with weekly charging), while NMC battery packs degrade faster, typically lasting 1500-2500 cycles. Factor in replacement costs—cheaper cells often have shorter lifespans.

8. Installation Recommendations for the Logan II

• Secure mounting: Use steel brackets to secure the battery pack, preventing movement during acceleration or braking.
• High-voltage wiring: Use high-voltage cables rated for 600V or higher with good insulation. Install fuses for the battery pack to prevent short circuits.
• Ventilation: If installing the battery pack in the passenger compartment, add ventilation to exhaust any trace gases (byproducts of overcharging) and prevent heat buildup.

Summary

Choosing a lithium-ion battery pack for your Dacia Logan II electric vehicle conversion ultimately comes down to balancing range, voltage, and size. Prioritize a 20-40 kWh LiFePO₄ battery pack with a matching BMS, and ensure it fits within your vehicle's weight and space constraints. By determining capacity based on daily needs and prioritizing safety features, you'll create a practical, reliable electric Logan II that will serve you well for years.

Before final installation, it's best to test the battery pack's performance in your local climate conditions—cold weather reduces battery capacity, so if you live in a cold region, consider adding a battery heating system. With careful planning, your battery pack will successfully transform the Logan into an economical and efficient electric vehicle ready for long journeys.