Power and energy

A 50 kg URC rover draws about 249 W on average and can pull 3.7 kW for a few seconds, a ratio of roughly 15 to 1. The average is what sizes the battery; the peak is what sizes the fuse, the contactor and the parallel count of the pack. Between those two numbers sits the energy budget, and it is dominated by the one mission that may run for a full hour: the 60-minute Delivery requires 145 Wh of mission energy and 273 Wh of nameplate capacity at 50 kg. The sample is a parameter model of eight mission cases plus the eight packs teams have published.

Average draw and peak draw

The subsystem power study produced a 50 kg, 35-minute load table at 249 W mean and 146 Wh, with a 3.7 kW everything-at-once peak. The mass-parameterised model reaches the same driving power from the other direction and splits it into mission stages, using the mission clocks published in the rules S-URC27-RULES §1.

The hotel load is nearly mass-independent, rising 37 % for a 43 % increase in mass, while the drive load is proportional to mass. A light rover is hotel-dominated and a heavy rover is drive-dominated. The two peak estimates differ because they answer different questions: 3.7 kW is what happens if everything runs at once, and 4.0 kW is a credible simultaneous event. Either way the peak is 120 to 160 A at 24 to 26 V, against an average of 95 to 160 W.

Energy by mission

These are model outputs, not measurements. The mission mixes that produce them are drive, arm, science and idle fractions estimated from the task content of each mission S-URC27-RULES §1.

From mission energy to a pack

The same chain gives 289 Wh for the back-to-back Autonomy then Equipment Servicing pair in one pack. The recommended pack for a first 2027 team is 400–500 Wh at 8S, lithium-ion 21700, 2.4–2.9 kg including BMS and enclosure. That covers the 289 Wh case with 38 to 73 % headroom, allows a second mission on one charge and keeps the pack small enough that a 4P current rating is comfortable.

The interactive view plots the eight packs in the data table that publish a nameplate energy, from 320 to 840 Wh. The static figure above shows the six largest of them against the modelled requirement.

Observed capacity runs 1.6 to 3.1 times the single-mission model. Four explanations fit the record better than “teams oversize”: a 120 A peak needs at least three cells in parallel for current alone, a second mission may follow within ten minutes, unmodelled hotel growth (West Virginia’s 2026 rover runs eleven cameras, a 3D lidar, three radios and two computers), and a lithium iron phosphate pack holds about 70 % more mass for the same energy, at 100 Wh/kg against 170 Wh/kg for lithium-ion. UIU’s pack grew from 432 Wh to 840 Wh across five generations while the rover mass stayed flat at 47.5–49.8 kg S-UIU-ROVER-PAGE-AURION S-WVU-SAR2026.

The values on this page