Reviving A Smart Fortwo Electric Drive Battery
- Hosea Embury
- Aug 19, 2025
- 3 min read
Updated: Feb 26
Understanding the Battery System
The Smart Fortwo Electric Drive (ED3) uses a lithium-ion battery that powers the vehicle. The battery is made of (93) individual pouch style cells wired in series. These cells are divided into 3 modules of (31) each. Over time, factors such as age, temperature fluctuations, and long periods of inactivity can diminish the battery’s ability to hold a charge and the available range. This is normal; however, the ED3 battery is a very robust, German-made battery and has been known to last much longer than other batteries made around the same time. With proper care, these batteries should outlast the car and easily get you Smart to the 150,000-mile mark.
The Weakness: Battery Management System
The weakness lies in the battery management system (BMS). The BMS in your Smart Fortwo closely monitors the battery’s health and performance. If the BMS senses that the battery charge is critically low, it may prevent the vehicle from starting to safeguard the battery from further damage. This feature helps prolong your battery's lifespan.
Another mis-programed function of the BMS is to deplete the charge from the HV battery if the low voltage (12V) battery has been removed, discharged, or in poor health for an extended period. This process is known as "Junkyard Mode." This "safety" feature prevents an electrocution situation if someone were to unknowingly tamper with a charged high voltage (HV) battery or HV wiring. This is irreversible program. It requires removal of the battery, cell revival, and possibly rewriting code in the BMS.
Common Symptoms of a Dead HV Battery
Before diving into solutions, let’s identify some common signs that indicate your Smart Fortwo's HV battery might be dead or bricked. Look out for these symptoms:
Dashboard warning shows "Drive Sys. Engine off," "HV System Workshop," or "Malfunction, Service Required."
Your vehicle does not respond when you press the accelerator in "R" or "D."
The battery will not charge even when connected to a charger.
The right gauge on the dash (powermeter) wont move from the "Off" position when attempting to start the car.
If you notice any of these issues, your battery likely needs some attention.
Troubleshooting the Charging Issue
Check the Charger and Connections First
The first step in troubleshooting is to ensure your charger is working properly. Inspect the charger for visible damage and ensure it is plugged into a functioning outlet. Also, check the connections between the charger and the vehicle. Loose or corroded connections can hinder the charging process.
You will need a scan tool capable of reading codes in every module, use it to clear the trouble codes in the BMS and any others. Look for codes (P1D799A) and (P18051C) The second code is the most undesired code that indicated a bricked BMS. If still nothing works and you are still unable to start, move, or charge your Smart, you may need to book a battery repair service with Embury Automotive.
Reviving the Battery
The revitalizing and repair process may take a few weeks to finish. This does not include the time to remove the HV battery pack from your Smart. Embury Automotive does not replace individual cells in the HV module if there are individual cells damaged or weak, recovery may be impossible. Replacing individual cells is usually unsuccessful because the BMS closely monitors differences in each cell's internal resistance.
Here is a DIY video: https://youtu.be/Mgh6KLAGYNU?si=PY6I9GJ9sgPgYGoC
Preventing Future Battery Issues
After repair, if successful, to avoid facing similar issues down the line, consider these preventive measures:
Regularly Drive Your Vehicle: If you don’t use your Smart Fortwo often, aim to drive it at least once a week to keep the battery active.
Maintain Battery Health: Check the 12v battery health every year and the terminals for corrosion occasionally and clean them if needed.
Store Properly: If you expect to store your vehicle for an extended duration, consider using a battery maintainer to keep the 12v battery charged.
Get Your Smart Fortwo Back on the Road
Reviving your Smart Fortwo Electric Drive battery might seem challenging at first. But with the right approach, you can get back on the road.
By familiarizing yourself with the battery system, troubleshooting effectively, and taking preventive measures, you can ensure your vehicle remains reliable and ready for your next adventure. Don’t let a dead battery hinder your enjoyment of the unique driving experience that the Smart Fortwo provides.
Take action today and revive your battery!
Here is the 2016 Smart from the video link.