The BMW i3, introduced in 2014, was celebrated as a pioneering electric vehicle (EV), thanks to its carbon-fiber frame, innovative design, and use of sustainable materials. However, its early battery performance left much to be desired, offering only around 80 miles of range when new. In colder months, the range dropped to under 60 miles. Over time, many early models struggled to exceed even 60 miles on a full charge due to battery degradation.
Now, more than a decade later, a Chinese company has provided a solution to the i3’s biggest limitation. Martigi Manufacturing (MTG), a company specializing in battery retrofitting, has unveiled a new, high-capacity replacement battery that promises to nearly triple the car’s original range. This upgrade is achieved without requiring significant vehicle modifications.
MTG’s upgraded battery pack uses advanced battery cells from China’s CATL, one of the world’s leading battery manufacturers. The new battery employs Nickel Cobalt Manganese (NCM) chemistry and retains the same external form factor, voltage, and configuration as the original BMW pack. The kit includes 96 CATL cells, arranged in eight modules, delivering a total capacity of 54 kilowatt-hours (kWh) and 154 amp-hours (Ah), a significant improvement over the original i3’s 18.2 kWh and 60 Ah.
This upgrade provides a 156% increase in capacity over the early i3 models and a 28% increase compared to the i3’s final 42.2 kWh battery pack introduced in 2019. Importantly, this retrofit is compatible with all versions of the i3, including the 60 Ah and 94 Ah models, which dominate the used i3 market today.
MTG’s retrofit system works with the car’s existing electrical systems, using a modified battery management system (BMS) developed in collaboration with Echi Tech, a Chinese tech company. The kit also includes all necessary wiring, connectors, and hardware. While MTG markets the retrofit as DIY-friendly, it advises professional installation due to the complexity of high-voltage systems involved.
Substantial Range Gains at an Affordable Price
The new battery brings impressive range improvements. MTG claims the 54 kWh battery allows the i3 to travel up to 248 miles on a full charge in ideal conditions. Real-world testing showed an i3 with the upgraded pack traveling 186 miles on the highway at a steady 62 mph, nearly tripling the range of many older i3 models.
The price of the upgrade is also noteworthy. The 154 Ah battery is listed at $5,800 on Alibaba, excluding shipping and installation costs. A smaller 120 Ah version, similar in size to BMW’s final i3 battery, is priced at $4,800. Both options come with a three-year warranty and are rated for 2,000 charge-discharge cycles.
For comparison, a new factory battery from BMW costs around $15,000 before labor, making repairs on older i3 models financially unfeasible. With the MTG upgrade, the cost equation shifts significantly. A well-maintained used i3 can be purchased for under $8,000. After installing the upgraded battery, owners can have a 250-mile EV for less than $16,000—cheaper than the base model of a Nissan Leaf.
This upgrade presents an affordable option for extending the life of older BMW i3s, offering a significant range boost at a fraction of the cost of a new vehicle.
