by Brian Woods
A reliable recorder will both be consistent in repeated use and performance, and will consume battery power at a rate that allows the researcher to anticipate the amounts of audio that can be collected before a recharge. To determine the overall reliability of the Evistr L53's internal battery prior to deploying it as a tool in field research, a few real-world tests were performed.
The Evistr L53 is quite a small recorder, and easily slips into a pocket. The build feels very sturdy. It features a rechargeable lithium battery, and 8GB of internal drive space. You have the option to either record via the two internal omnidirectional microphones, or with an external 3.5mm line-in or microphone (not included). Audio is captured in .mp3 format. The Auto Record feature might be the most alluring setting for researchers who place recorders for long term audio collection. A scheduled and recurring recording can be set, and the recorder will automatically become active and begin a new file, for the length of time you have designated. Files are transferred from the recorder to a PC with a micro USB cable, which is included. The internal battery is recharged with this same cable.
The longevity and performance of the battery will be tested using two identical L53 units, both fully charged and formatted back to default factory settings. It's important to note that the recorder does not display a percentage number of remaining battery life, but instead uses a simple icon that becomes less “full" as it is used. At the conclusion of the tests, the total recording times of each recorder will be tallied, and comparisons will be made between the two. The system date and time was set on both, and the Long Time Recording feature was selected. This particular feature will cause the recording to be captured in 64kb. The Auto Record option was enabled on only one of the recorders, and a five hour recording was scheduled to begin every twenty four hours at 10:00 PM. We'll call this “Recorder A". The power switch was left in the ON position on Recorder A. This enables the recorder to enter a standby mode between scheduled recordings. As the recordings complete, Recorder A will be examined to determine the remaining battery life. This test will be performed with an external microphone connected to the recorder, and with the recorder resting in a waterproof box outside.
The second recorder will be referred to as “Recorder B". It will be tested differently, focusing on the total number of hours the battery will operate when long, uninterrupted recordings are made. Recorder B will also be tested outdoors in the weatherproof box mentioned earlier.
By using two recorders and testing each one differently, it may be possible for the researcher to observe these test results and decide if the Evistr L53 is an appropriate and capable recording device for their needs. Battery levels will be monitored and noted, and the test will be considered complete when either the batteries are too low to enable the collection of additional recordings, or the collected results help contribute to a satisfactory understanding of what the user can expect from the L53.
Immediately before the scheduled recording began, it was confirmed that the battery level was still at 100%. The external microphone was connected, and the unit was placed in a safe spot outside, within the weatherproof box. The first scheduled five hour recording started and ended successfully, and the battery still displayed full. The second recording also was successful, as well as the third. At this point, the recorder had a total of fifteen hours recorded, and indicated a remaining battery level of ¾. The fourth recording completed the next day, and then the fifth. Inspecting the recorder revealed a remaining battery level of ¼. The total time recorded at this point was 25 hours. It was during the sixth recording that the recorder shut itself off due to low battery. This final recording session was three hours and forty six minutes long, bringing the grand total to twenty eight hours and forty six minutes.
Recorder B was fully charged and placed into the weatherproof box, outdoors. The recorder was placed in active recording mode, and a ten hour recording was completed. At this point, the battery appeared to have used ⅔ of its charge. A second recording was started. When the battery level was checked several hours later, it was found that the unit had switched itself off due to low battery. The length of the recording was four hours and twenty minutes. In total, Recorder B’s battery was able to provide power for fourteen hours and twenty minutes of long, uninterrupted recording.
The overall performance and reliability of a particular research tool are important factors for a field researcher to consider, when projects are being formulated and enacted. This is especially the case for projects that involve both long term and shorter, interim collections of audio data. In advance of deploying this recorder for any long term audio collection field projects, the internal lithium battery needed to be tested under conditions similar to real-life projects.
When assessing the battery’s performance, it's safe to declare that the recorder does experience a much faster depletion of battery when long, uninterrupted recordings are made (Recorder B). In fact, twice the number of hours were recorded by Recorder A, even with the recorder sitting in standby mode for 19 hours between scheduled recordings.
The L53 would work well as both a portable recorder, and as part of a deployable system for longer term projects. Perhaps only scheduling two hours of recording per day would keep the battery going for ten to fourteen days.
The Evistr L53 digital audio recorder is available from online merchant Amazon.com. Other audio recorder models with the Evistr brand were also available, but the features and performance of these others were not assessed or considered. Initially, the L53 was selected due to the presence of the Auto Record feature, and the affordable price of approximately $45.00 USD.