Why does my electric vehicle need a separate SLI Battery?

Every electric vehicle uses a 12-volt auxiliary battery to power the electrical systems and traction battery management. These are simpler, cheaper, maintenance free, and safer than the 400V or 800V powertrain batteries that power the vehicle.

Eurobat Battery Innovation Roadmap 2030

Eurobat Battery Innovation Roadmap 2030 – Lead Acid Batteries

EUROBAT Parameters		2020 State of the Art	2030 Target	UBC 2021
Electrochemical System	Cathode	PbO₂	PbO₂	PbO₂
Electrochemical System	Anode	Pb, Pb+C	Pb, Pb+C	Pb, Pb+C
Energy Density (Wh/Kg)	Battery	23 – 45	35 – 55	52 – 68
Energy Density (Wh/l)	Battery	36 – 100	50 – 110	112 – 139
Power Density (W/Kg)	Battery	41 – 400	65 – 450	380 – 410
Power Density (W/l)	Battery	76 – 840	72 – 900	820 – 920
Predicted Lifetime (Yr)	Calendaric	10 – 25	10 – 25	10 – 25
Operation Temperature Range (^oC)		-25 – +50	-25 – +50	-40 – +88
Energy Efficiency (%)		67 – 85	>90	85 – 90

EUROBAT = Association of European Automotive and Industrial Battery Manufacturers. The purpose of the association is to study all matters of interest to storage battery manufacturers and their sub-contractors in Europe, the Middle East and Africa.