1
Health Indicator Development for Low-Voltage Battery Diagnostics and
Prognostics in Electric Vehicles
Xinyu Du
1
, Huaizheng Mu
2
, Kevin Corr
3
, Matt Nowak
4
, Hong Wang
5
, Tung-Wah Frederick Chang
6
, and Sara Rahimifard
7
1,2,3,4
General Motors Global Technical Center, Warren, Michigan, 78092, USA
xinyu.du@gm.com
huaizheng.mu@gm.com
kevin.corr@gm.com
mateusz.nowak@gm.com
5,6,7
General Motors Canadian Technical Center, Markham, Ontario, L3R4H8, Canada
hong.wong@gm.com
tung-wahfrederick.chang@gm.com
sarasadat.rahimifard@gm.com
ABSTRACT
Each electric vehicle (EV) requires a low-voltage (e.g., 12V)
auxiliary battery to provide electric power to onboard
electronic control units, lighting systems, and various sensors
during power off. Therefore, when the low-voltage battery is
in low state of health (SOH) or low state of charge (SOC), it
may cause no-start events. The existing OnStar Proactive
Alert service can effectively predict low SOC or low SOH
events for low-voltage batteries in Internal Combustion
Engine vehicles using cranking signals. However, it does not
work for EVs since there is no cranking event. In this work,
a diagnostic and prognostic solution for the low-voltage
battery of EVs is proposed. Four novel health indicators (HIs)
along with the decision-making system are developed based
on equivalent circuit models. Furthermore, the selection
process of appropriate HIs tailored to various operational
states of the vehicle is described. The validation results based
on GM test EV data have demonstrated the effectiveness and
robustness of the proposed solution.
1. INTRODUCTION
The move towards zero emissions has led to the fast growth
of electric vehicles (EVs) as a practical alternative to
traditional internal combustion engine vehicles (ICE). EVs
are acclaimed for their environmental benefits and reduced
operational costs. Electric vehicles commonly incorporate
high-voltage (HV) batteries as their primary power source,
complemented by a secondary 12V low-voltage (LV)
auxiliary battery. The LV battery supplies power to various
auxiliary systems such as lights, audio systems, air
conditioning, electronic control units (ECUs), power
windows and infotainment system (Emadi, Williamson, & A.
Khaligh, 2006) (Hou, Magne, Bilgin, & Emadi, 2015)
(Hasan, Mahmud, Habib, Motakabber, & Islam, 2021)
(Wang, Zheng, & J. Bauman, 2023). These auxiliary systems
play crucial roles in the normal operation of electric vehicles,
underscoring the critical importance of the LV battery.
Although the LV battery is not responsible for directly
powering the electric vehicle, its malfunction can yield
significant consequences. First, the LV battery supplies
electric power to the vehicle's ECUs during startup; a faulty
battery may result in no-start events. Second, various low
voltage electric systems rely on the 12V battery. A faulty
battery may render these systems inoperative. In some
situations, it may impact propulsion system, steering system,
or braking system (e.g., Anti-lock Braking Systems (ABS),
Electronic Stability Systems (ESC)). Last but not the least,
the charging system and cooling system for HV batteries rely
on the 12V battery. A faulty LV battery may lead to
malfunction of HV battery thermal control in some corner
cases. In summary, the health of the 12V battery is critical to
ensure EV performance.
For current ICE vehicles, LV battery diagnostics and
prognostics rely on cranking signals (Du & Zhang, 2018),
which is unavailable for EVs. Making it even more
challenging is the fact that the LV battery in EV lacks
excitation since the battery is under charging most of time
during driving or during power off with external charger
plugged in for HV batteries. To this end, the existing LV
battery prognostic algorithms for ICE vehicles can’t be
Xinyu Du et al. This is an open-
access article distributed under the terms
of the Creative Commons Attribution
3.0 United States License, which
permits unrestricted use, distribution, and reproduction in any medium,
provided the original author and source are credited.
