Lithium battery pack and BMS requirements for an e-rickshaw

Yamuna Mobility builds about 900 e-rickshaws a month. Each one carries four 12 V, 130 Ah lead-acid batteries that weigh about 120 kg and last barely a year in Delhi's heat. Drivers complain that range falls from 80 km to under 50 km by the end of the first summer. Fleet owners want lithium, and the company wants a pack design it owns, not a black box bought off the shelf.

The vehicle and its use: - 1.2 kW BLDC hub motor and a 48 V controller that works from 42 V to 60 V, peak current 60 A; - vehicle mass without battery 280 kg, plus driver and four passengers at about 300 kg; - a day is about 100 km of stop-start driving at up to 25 km/h, with a stop every 300 to 400 m and a few flyover ramps of up to 6% gradient; - summer ambient reaches 46 °C, and the pack sits under the passenger seat in a closed steel box.

The product manager's targets are: - 100 km a day on one overnight charge, even when the pack has aged to 80% of its capacity; - at least 2,000 cycles; - pack mass under 45 kg and cell cost under ₹48,000; - compliance with India's AIS-156 battery safety requirements for the vehicle category.

You will build a drive-cycle energy model in Python, choose LFP cells and a series-parallel arrangement, estimate peak current and heating, and write the BMS requirements and a safety checklist. No hardware is needed. The model, the thermal estimate and the documents are all done on a laptop with public datasheets.

Done looks like a pack proposal the company can send to cell and BMS suppliers for quotes: energy model, pack configuration, thermal estimate, a requirements document with numbered, testable requirements, a safety and compliance checklist and a cost estimate. If 45 kg and 100 km at end of life cannot both be met, show the trade-off.