I am trying to set up a 7-day continuous recording at a 48kHz sample rate. However, when using 1.5V rechargeable lithium-ion batteries, I am encountering severe SD card read/write errors. This issue is highly prevalent among a batch of 30 newly purchased devices. Under the exact same configuration, about 1 in 6 devices experiences this issue, and the behavior is becoming increasingly unpredictable.

Hardware Tested:

• SD Cards: Kingston Canvas Select Plus (256GB); SanDisk High Endurance (32GB, 64GB, 128GB).

• Batteries: 1.5V Constant-Voltage Li-ion: iNeno AA (3700mWh), Sidande AA (3600mWh); Panasonic NiMH rechargeable (2300mWh); Standard Alkaline batteries.

Observed Issues:

1. Battery Performance Discrepancies:

   • Panasonic NiMH and Alkaline batteries: Recording is completely stable with zero errors, but their battery capacity is insufficient for the required 7-day duration.

   • 1.5V Li-ion batteries: Frequently trigger SD card read/write errors (indicated by alternating red and green flashing LEDs).

2. File and Configuration Anomalies: When errors occur, the behavior is inconsistent. Sometimes a WAV file header is successfully generated, but other times the device fails to even read or create the basic CONFIG.TXT file.

3. Sensitivity to Recording Duration: Short recording intervals (e.g., 5-10 minutes) easily trigger errors. Surprisingly, longer continuous recordings (e.g., recording for 6 hours on a 64GB card, or 12 hours with a 5-second sleep interval on a 128GB card) are much more stable.

High Variability Across the 30 Devices: When powered by 1.5V Li-ion batteries, device behavior varies greatly depending on the SD card used. While most devices can support the 64GB cards, 6 devices immediately show read/write errors when using the SanDisk 128GB cards, and most devices immediately throw read/write errors when using the Kingston card.

Testing Summary: Out of 20 test runs, only two configurations succeeded: 32GB @ 16kHz and 64GB @ 32kHz. Contrary to existing reports/documentation, the Kingston card performed poorly, whereas the SanDisk card—despite having higher power consumption—was at least able to record for a short period. I will continue testing different hardware combinations until I achieve a stable 48kHz configuration.

Questions: I have read through many issues posts, but most report anomalies occurring midway through a recording. In my case, read/write errors appear immediately upon starting.

1. What can be done if using 1.5V constant-voltage Li-ion batteries causes SD card write failures or prevents the reading/creation of the CONFIG.TXT file?

2. To stably achieve a 7-day continuous recording at 48kHz, what hardware configuration (SD card model/capacity + battery/power solution) would you recommend?

Thank you in advance for your advice!

Regards,

KC