1. Logic of 12V Lithium Battery Replacement

Lithium battery adoption is applied in traditional fuel vehicles, 48V/HEV and pure electric vehicles. The main restricting factor is cost. This attempt can be traced back to 2012 when A123 developed products for Daimler.

In the traditional vehicle sector, luxury carmakers such as BMW, Audi and Mercedes-Benz took the lead. Previous models include BMW M3/M4, Mercedes AMG, GLC, S-Class, SLS AMG Coupe, SLS, S63 AMG, S65 AMG Coupe, and Porsche sports cars. After BMW included LG Chem in its supplier system, lithium batteries were mainly used to replace lead-acid batteries.
Starting from 2021, Mazda followed in the hybrid field, while Hyundai and Kia began promoting replacements in pure electric vehicles. There is no short-term plan for BEVs, but the future trend is similar to hybrids. The design perfectly integrates 12V lithium battery, DC/DC and high-voltage HEV batteries.

The core reason for replacement lies in environmental recycling under European regulations. In 2019, the European Commission proposed banning four lead compounds in future batteries: lead monoxide, trilead tetroxide, lead oxide sulfate, etc.
Current lead-acid usage faces strict recycling obligations. The Directive addresses the risks in two ways: 1) by reducing hazardous components in batteries; 2) by ensuring proper waste battery management.
Industry associations believe alternative technologies remain costly, slowing down full lead-acid phase-out.

2. FCA 12V Mild Hybrid System

When launching the new FIAT 500e with a 42kWh battery, FCA also released two 12V mild hybrid models: FIAT 500 and FIAT Panda equipped with a 1.0L 69HP three-cylinder engine, a 51kW motor and a 12V 11Ah lithium battery. This low-cost BSG system reduces CO₂ emissions by up to 30% for A00 segment cars. The motor is mounted directly on the engine, lowering the powertrain by 1.7 inches compared with older models:

This 11Ah 4S1P lithium battery has a rated voltage of 13.5V and weighs 4kg. In Europe, 48V systems are widely promoted for emission reduction on Daimler, BMW and Audi. For A00/A0 vehicles, manufacturers either adopt full BEV or low-cost 12V lithium solutions with only 4 cells (0.15kWh). This solution will spread faster than large vehicle 48V lithium upgrades, directly replacing traditional 12V AGM batteries.

Summary: Major suppliers including GS Yuasa, LEJ, CATL, LG Chem, Samsung SDI and Wanxiang A123 have advanced significantly in 12V/48V lithium batteries. Greater changes will take place starting from 2020.

Source: Automotive Electronics Design Author: Zhu Yulong