A charging log can survive a clock change if you record elapsed time independently or save both endpoint timestamps with their dates and UTC offsets. Subtracting two local clock labels alone can give the wrong duration when an hour repeats, disappears, or changes during travel. If you have neither a reliable elapsed reading nor trustworthy, fully specified endpoints, mark the duration unknown. A plausible guess is not a measurement.
This is a recordkeeping method for an attended charging session conducted according to the equipment instructions. It does not establish how long a station needs to charge, how much energy it accepted, or whether a particular charger is compatible.
Why the clock on your phone is not the whole record
Local time tells you when something happened in a particular place. Elapsed time tells you how much time passed. They usually appear to agree, which makes a clock adjustment easy to miss.
NIST explains that the U.S. daylight saving transition can skip a local hour in spring and repeat one in fall, in places observing those changes. A repeated label such as 1:30 a.m. therefore needs more context. This guide does not assume your campsite observes daylight saving time or give a calendar date for your trip.
An elapsed timer can provide a separate basis, but the word “timer” on an app is not proof of its behavior. Microsoft documents that Windows QueryPerformanceCounter is independent of system-time changes and that its Stopwatch class uses that counter. That is a documented software example, not verification of your phone app, station screen, or meter. Check the documentation for the actual tool you use, including what happens after a pause, restart, or device shutdown.
Choose a timing basis before the session
- Identify the session. Record the station model, charger, input method, and which event defines the start and finish. “Connected” and “charging indication appeared” are different observations.
- Record the full date and clock label. Include seconds only if your observation supports that precision. Keep the original entry.
- Save the UTC offset at each endpoint. A numeric offset such as UTC−04:00 specifies the relationship to UTC at that observation. A zone nickname alone may leave ambiguity.
- Record an independent elapsed reading when available. Note its starting value, ending value, and any reset or pause. Do not assume it started at zero.
- Reconcile discrepancies. If the two methods disagree, preserve both and investigate the time source before reporting one duration.
A manual clock correction is a separate problem from a time-zone display change. Adding an offset does not repair an incorrectly set clock. Endpoint subtraction is useful only when the endpoints represent trustworthy instants.
A log that makes the evidence visible
| Observation | Local date and time | Offset and source | Elapsed reading | Configuration or status |
|---|---|---|---|---|
| Start event | Record original label | Record numeric offset and clock source | Record starting value | Model, input, event definition |
| Clock adjustment or interruption | Keep before/after labels | Note automatic or manual change | Note continuity, reset, or missing reading | Record any charging interruption separately |
| Finish event | Record original label | Record endpoint offset and source | Record ending value | Finish definition and observed status |
| Result | Preserve raw entries | Explain conversion basis | Calculate only a supported difference | Valid interval, partial interval, or unresolved |
For offset-aware timestamps, convert each endpoint to UTC, then subtract start from finish. For a continuous elapsed counter, subtract its starting reading from its ending reading. If charging stopped within the interval, the session duration and active charging duration are different quantities. A timer that kept running does not fill in the missing charging history.
Three hypothetical records
The following numbers illustrate time arithmetic. They are not FlashFish charging tests or recommended charging periods. “Day A” means the same fictional local date in each endpoint pair.
Example 1: A repeated local hour
Start is Day A, 01:40 at UTC−04:00; finish is Day A, 01:20 at UTC−05:00. Those endpoints correspond to 05:40 and 06:20 UTC. The duration is 40 minutes, even though the finish clock label looks earlier. This result depends on the recorded offsets and trustworthy clocks.
Example 2: A skipped local hour
Start is Day A, 01:50 at UTC−05:00; finish is Day A, 03:10 at UTC−04:00. Converted endpoints are 06:50 and 07:10 UTC: 20 minutes apart. Subtracting local labels would incorrectly produce 80 minutes.
Example 3: Missing offsets, with and without a timer
A note says only “1:40 to 1:20.” It cannot establish duration. If a separately documented continuous timer was recorded at 00:05:00 and 00:45:00, its difference supports 40 minutes. Without that evidence, leave the duration unknown; do not choose whichever interpretation resembles an expected charging time.
Where E103 and T200 fit
FlashFish E103 is specified at 179.2Wh and T200 (TELLUS-T200) at 153.6Wh. These are capacity fields that help identify the records. Neither supplies a duration for your session or verifies your timekeeping tool.
The E103 source manual is a 230V variant; its AC details should not be transferred to a U.S. unit without exact variant confirmation. Before using either model, match the unit and charging equipment to the applicable instructions. Choose a station for the documented inputs and outputs your setup requires, then keep timing observations separate from capacity specifications.
What a valid duration still cannot tell you
Forty minutes of elapsed time does not establish watt-hours accepted. That requires suitable energy measurements or a documented power record with known intervals. A display snapshot is not a continuous record. Likewise, a change in displayed battery percentage is not, by itself, a calibrated energy measurement.
Keep incomplete sessions labeled incomplete. If a new observation is needed, plan a separate attended session under the applicable instructions. Do not extend a session merely to repair a log.
Frequently asked questions
Can I use screenshots of the start and finish?
They can preserve observations, but check whether they contain the date, offset, and relevant charging status. A screenshot of a local clock alone may retain the same ambiguity as a handwritten note.
Should I add an hour whenever the clock goes backward?
No. Use the actual endpoint offsets or a documented elapsed record. A manual correction or travel-related display change may differ from the daylight saving transition you had in mind.
Does a correct log prove a model charges faster?
No. A speed comparison needs a defined charging task and comparable conditions, not just correct timestamp subtraction. Keep this result limited to the interval you can support.
Before choosing equipment for your next trip, complete the model and input fields, identify the applicable charging instructions, and decide how you will record elapsed time. That gives you a practical basis for comparing station details without treating an ambiguous clock label as performance evidence.
Next step: Compare FlashFish E103 specifications with your equipment list.
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