# Donut Lab Battery Test 3 - NOT What I Expected!

Source: https://www.youtube.com/watch?v=nYdYyomuG2M
Recap page: https://rapidrecap.app/video/nYdYyomuG2M
Generated: 2026-03-10T07:02:00.014+00:00

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## 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.

![Screenshot at 00:54: The DL1 self-discharge test results after 10 days show that the actual charge retention \(97.7%\) is close to the ideal, losing only 2.3% capacity, contrasting sharply with the supercapacitor benchmark which loses half its voltage by day 9.](https://ss.rapidrecap.app/screens/nYdYyomuG2M/00-00-54.jpg)

**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.

### Self-Discharge Test Results

- Test 3 showed a less ideal voltage relaxation profile compared to Tests 1 and 2, but still retained 97.7% capacity after 10 days, significantly outperforming a supercapacitor benchmark.

### OCV Fingerprint Analysis

- The DL1 cell measured 3.745V at 50% SOC, matching the established operating voltage range for NMC Lithium-ion cells (3.65V - 3.75V), confirming its likely chemistry.

### Thermal Performance

- Test 3 included a discharge test at 80°C, after which the cell successfully accepted a full charge, indicating good high-temperature stability.

### Community Sentiment Analysis

- The most frequently discussed themes in comments were Energy Density/Weight (81 mentions), Lifecycle Degradation Concerns (41 mentions), and Drip-Food Pacing Frustration (18 mentions).

### VTT's Role and Credibility

- The community noted that VTT is working on behalf of Donut Lab, leading to skepticism about the objectivity of the testing, ranking 'VTT is a Lab, Not an Auditor' as the 9th most discussed theme.

![Screenshot at 00:11: A comparison of four graphs showing Voltage, Current, Temperature, and Capacity over time for the initial test cycles.](https://ss.rapidrecap.app/screens/nYdYyomuG2M/00-00-11.jpg)
![Screenshot at 00:54: A digital dashboard illustrating the results of the 10-day self-discharge test, showing the actual charge retained \(97.7%\) versus the ideal retention.](https://ss.rapidrecap.app/screens/nYdYyomuG2M/00-00-54.jpg)
![Screenshot at 03:34: A detailed section of the VTT report highlighting the voltage drop over time during the self-discharge period, showing a 118mV drop after 10 hours.](https://ss.rapidrecap.app/screens/nYdYyomuG2M/00-03-34.jpg)
![Screenshot at 03:55: A bar chart comparing the Open Circuit Voltage \(OCV\) at 50% SOC for DL1 against NMC, LFP, and Na-ion batteries, showing DL1's voltage is within the NMC zone.](https://ss.rapidrecap.app/screens/nYdYyomuG2M/00-03-55.jpg)