ASC 2024 regulations restricted the SOV battery pack by setting a maximum weight per regs 8.2.A.1. The exact weight depended on the specific chemistry used. MS15 used a Li-Ion NMC chemistry cell, giving it a 20kg weight limit.

One small problem with limiting the batteries based on weight, was that some top teams who had access to ultra-high (gravimetric and volumetric) energy dense silicon nanowire anode cells from Amprius Technologies ended up having a significant battery capacity advantage. UMichigan reported having 3kWh more energy than a conventional Li-Ion battery pack, and Innoptus reported having 30% more energy than their previous battery pack [13].

Most likely to prevent already successful teams from having an even stronger advantage over everyone else, WSC and ASC decided to move away from limiting battery storage by a weight limit and have moved to limit the battery by setting a maximum energy (11MJ or ~3.05kWh for WSC2025, waiting for reg-drop from ASC for ASC 2026).