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A data center
the size of a keg.

Three Raspberry Pi 5 nodes, one 100 W solar panel, one 256 Wh battery, sealed in a stainless keg painted safety orange. Built for under $1,000. Instrumented so every design claim becomes a measurement, then published.

See Keg-1Read the preprint
Keg-1 cross-sectionA five-gallon stainless keg in section. Three Raspberry Pi 5 nodes on the left wall conduct heat through a 3 mm aluminum plate to the keg shell. A fuse block, three buck converters, and a gigabit switch sit on the right. Sealed penetrations are on the upper sidewall. Four temperature probes, a humidity sensor, and desiccant are marked.DS18B20, airDS18B20, SoCDS18B20, outsideDS18B20, wallPi 5 ×33 mm Al plateIP68 gland, 12 V inRJ45 bulkhead, data outGbE switch3× buck 5.1 VFuse block B1–B5silica gelBME280pressure-relief valve, never disabled5 gal 304 stainless ball-lock keg, ≈ 8.5 in × 25 in
Phase
0Pre-build
Measurements
0logged
Claims under test
10graded
Budget
$1,000$0 spent
As of
2026-10-26

Keg-1 hardware begins after the move to Seguin, Texas. Next gate: Phase 1 gate: node 1 runs from the fused bus; both INA226s report watts.

Small on purpose. Cheap on purpose. Instrumented on purpose.

The questions that matter about data centers, how energy becomes computation, how heat leaves a sealed box, how a shared power budget is split among competing loads, are usually studied at the scale of a warehouse. They can be studied at the scale of a keg. Keg-1 is not built for throughput. It is built so that every abstraction in a data-center curriculum ends in a number read on a $25 multimeter.

Energy

PLAUSIBLE

256 Wh

12.8 V × 20 Ah LiFePO₄, 80% usable

A 100 W panel that is also the sunshade feeds an MPPT controller, then a fused 12 V bus with five branches, one per node, one for the switch, one spare.

Compute

VERIFIED

3 × Pi 5

1 GB each, wired gigabit, no Wi-Fi

A steel keg is a Faraday cage. Nodes talk over a five-port switch; one outdoor Cat6 leaves through an IP68 bulkhead. Node 1 hosts the sensors and the log.

Hall

SPECULATIVE

0.50 m²

stainless shell, fanless

Each SoC conducts into a 3 mm aluminum plate bolted to the keg wall. The shell is the radiator. The bet is that passive conduction is enough for three nodes.

The governing problem

The scheduler, not the panel, is the design.

Over a 14-hour winter night three idle nodes draw about 179 Wh and finish the night with roughly 26 Wh above the reserve. Three nodes at full load would need 366 Wh, which the battery does not hold. Night compute must be scheduled against a 26 Wh margin, about six node-hours of full load. Every input here is a pre-build estimate. The first overnight log redraws the lines.

Battery energy through a 14-hour winter nightThree lines fall from 256 watt-hours. Idle ends the night at about 77 watt-hours, above the 51 watt-hour reserve. Full load crosses the reserve at about 7.9 hours.06412819225602468101214hours after sunsetWhreserve, 51 Whfull load crosses the reserve at 7.9 h77 Wh at dawn
3 nodes idle, 12.8 W1 node full, 2 idle, 17.2 W3 nodes full, 26.1 W

Four phases. Four volumes. One gate each.

Parts are bought when their chapter is being studied. A phase ends only when its bench test passes. The curriculum, Poles, Chips, and Halls, climbs five rungs in each domain, from sixth grade to doctoral research questions, and each rung ends on the bench.

  1. 01

    Energy

    Weeks 1–4. Vol. I, Poles. $315

    Panel, MPPT controller, LiFePO₄ battery, the main fuse, the fused 12 V bus, and the first node as sensor host.

    Gate. Node 1 runs from the fused bus; both INA226 monitors report sensible watts in and watts out.

  2. 02

    Compute

    Weeks 5–8. Vol. II, Chips. $185

    Nodes 2 and 3, the gigabit switch, wired network, and a three-node load test under a stop rule set in advance.

    Gate. Three-node load test completes under the pre-set stop rule without a brownout.

  3. 03

    Keg

    Weeks 9–12. Vol. III, Halls. $265

    Primer and safety-orange paint, IP68 gland and RJ45 bulkhead, the passive heat path to the keg wall, sensors, desiccant.

    Gate. Water-only leak test of the empty keg, then a seven-day sealed soak with a flat humidity trend.

  4. 04

    Deploy

    Weeks 13–16. Vol. IV, Deployed. $65

    Land, tethered water, and a ground-based orbit analog: simulated eclipse power cycles and radiation-only cooling.

    Gate. Eclipse cycles logged; radiation-only cooling run completes with SoC below throttle.

Four rules on every week

  • Fuse first.

    The main fuse goes on the battery's positive terminal before anything else is connected.

  • Never pressurize the keg with electronics inside.

    The pressure-relief valve is never disabled or painted over. Leak tests use water on the empty keg, never gas.

  • Water tests are tethered only.

    A pool, a private pond, or a permitted dock. No open water in v1.

  • Orbit is a ground analog.

    Simulated eclipse power cycles and radiation-only cooling. Nothing launches.