New Tesla Patent Details Trailer-Mounted Dual-Battery Range Extender
New filings outline an auxiliary pack in a towable unit, managed alongside an 800V main battery for smarter fast charging.
Summary
- Tesla has published a new patent detailing a sophisticated dual-battery management system designed to serve as a range extender
- The application highlights a configuration where an auxiliary battery pack is mounted inside a towed trailer to mitigate range degradation
- The system uses specialized software to manage power flow and fast charging between an 800V primary battery and a 400V auxiliary unit
A newly published patent application from Tesla reveals ongoing development of a dual-battery range extender system, presenting an innovative solution to combat the significant range loss associated with towing. Filed in August 2024 and published in February 2026, the patent outlines a control architecture that manages a vehicle’s primary high-voltage battery alongside an auxiliary unit. Notably, the documentation details a configuration where the secondary battery pack is integrated into a towed trailer and connected via a high-voltage interface at the hitch.
The proposed system addresses the complex electrical coordination required to run an 800V primary battery and a 400V auxiliary pack simultaneously. It features three distinct operating modes, including a state-of-energy balancing function that ensures both batteries drain proportionally during normal driving. Additionally, an open-circuit voltage matching mode activates when routing to a fast charger, equalizing the packs to safely prepare them for parallel charging. While Tesla previously canceled its bed-mounted Cybertruck range extender, this patent suggests the underlying software and power management technology remains a key focus for the automaker.
