Donut Lab Battery Test 3 - NOT What I Expected!

Quick Overview

Donut Lab's third test (Test 3) was a slight step back from the previous two, showing a voltage drop profile that was less ideal than the initial tests, though still significantly better than commercial supercapacitors, while the analysis of community comments suggests high interest in energy density, lifecycle degradation, and cold temperature performance.

Key Points: Test 3 used a different methodology than Tests 1 and 2, resulting in a less ideal voltage relaxation curve after charging. The self-discharge test showed the Donut Lab cell retained 97.7% of its charge after 10 days, losing 2.3% capacity, which is significantly better than a supercapacitor losing over 50% in the same period. The Open Circuit Voltage (OCV) at 50% State of Charge (SOC) for the Donut Lab cell (DL1) was 3.745V, matching the Lithium Nickel Manganese Cobalt (NMC) range (3.65-3.75V) but significantly higher than LFP (3.30V) and Na-ion (2.8-3.2V). Community comments overwhelmingly focused on Energy Density/Weight, followed by Lifecycle Degradation Concerns and Drip-Food Pacing Frustration, indicating these are key areas of public interest. Test 3 featured a high-temperature discharge (80°C), which resulted in the cell accepting a full charge afterward, implying good thermal stability under stress. The presenter noted that the self-discharge test results were not as compelling as Test 2, and the OCV test confirmed the cell chemistry aligns closely with NMC Li-ion batteries.

Context: The video analyzes the third independent validation test (Test 3) conducted by VTT on a Donut Lab solid-state battery cell (DL1), comparing its performance metrics against previous tests and general industry benchmarks for other battery chemistries like NMC, LFP, and Sodium-ion. The presenter also reviews community sentiment gathered from comments across all three testing videos to gauge public interest in specific performance areas.

Detailed Analysis

The video dissects the results of Donut Lab's third validation test (Test 3) performed by VTT on the DL1 solid-state cell, noting that while the initial performance in Tests 1 and 2 was highly impressive, Test 3 showed a slight performance regression. The voltage relaxation curve in Test 3 was less flat than the previous tests, indicating a faster initial voltage bleed after charging, although it still maintained 97.7% charge retention over 10 days (a loss of 2.3% capacity), which is vastly superior to a comparative supercapacitor benchmark that lost over 50% charge in the same timeframe. Test 3 also included a high-temperature discharge at 80°C, after which the cell successfully accepted a full charge, suggesting good thermal robustness. Furthermore, the Open Circuit Voltage (OCV) measurement at 50% SOC confirmed the cell's chemistry signature (3.745V) aligns exactly within the expected range for NMC Lithium-ion cells, effectively debunking any notion that it was a different, exotic chemistry. The presenter concludes by summarizing community feedback, noting high interest in energy density, lifecycle concerns, and cold-weather performance, while pointing out that the overall testing series appeared structured more like a marketing campaign than pure technical validation.