Tesla charging history: sessions, energy and cost in one timeline

Charging cost tracking by session: methods and examples

What should a Tesla charging cost tracker actually track?

The headline number is simple: how much did charging cost? The hard part is making that number explainable. A Tesla can be charged at home overnight, at home during an expensive peak period, at work, at a Supercharger and at third-party public chargers in the same week. Those sessions can use completely different price rules.

A good tracker therefore does not begin with one average price per kWh. It begins with the charging event and keeps enough context to calculate or verify the cost later.

DriveQuery is being designed around this structure: keep the charging event first, then attach the relevant cost context. That is more useful than a number that looks precise but cannot be traced back to the session that produced it.

Tesla already has Charge Stats — where does a separate tracker help?

Tesla's Charge Stats is already useful. Tesla says the graph can show Total Charged or Total Spent, and charging is colour-coded by location type. Home rates can be configured, including time-of-use periods, while Work and Other locations can use configured or estimated rates.

That answers the broad question well: roughly how much energy and money went into charging over a selected period? A separate tracker becomes useful when you want to keep the underlying sessions, price assumptions and billing evidence together for longer-term analysis or reporting.

• Session-level traceability. Tesla states that charging in Charge Stats is aggregated by charging-location type for each day. A session ledger keeps individual events separate.
• Mixed evidence. Home charging may be an estimate from your electricity tariff while a Supercharger session has a final Tesla invoice.
• Dynamic tariffs. The relevant price can change by hour or quarter-hour, so the charging timestamp matters.
• Custom reporting. A tracker can build month, quarter or employer-reporting periods from the same underlying history.

How charging cost is calculated session by session

For a straightforward energy tariff, the basic calculation is:

The important phrase is applicable price. A charge that began at 01:15 on an off-peak tariff may have a different cost from an otherwise identical charge at 18:15. On a dynamic tariff, one long charging session may even span several price intervals.

For that reason, a tracker should retain the time and price context rather than store only the final amount. If the electricity tariff changes later, old sessions should still show the basis that was used at the time.

Flat, time-of-use and dynamic tariffs need different logic

If your goal is not only to track the price but actively move charging into cheaper periods, see the Tesla dynamic-tariff charging guide and smart charging guide.

Third-party public charging needs a fallback hierarchy

Public charging outside Tesla can be messy. Networks can bill by kWh, by minute, with a connection fee, through a membership plan or with roaming mark-ups. The amount first shown by the charger may not even be the final settled amount.

A practical tracker can use a simple hierarchy:

1. Final invoice or receipt when available.
2. Known session tariff if the final billed amount is unavailable.
3. Estimated tariff only when nothing stronger exists — and clearly label it as an estimate.

This preserves a single charging history without pretending all sources have the same accuracy.

A real example: one week, four different price bases

Consider an illustrative week. The rates below are examples, not current market prices.

A single average rate would give you the £38.19 headline, but it would hide the useful part: only 17% of the week's energy was taken at the expensive public charger, yet that session represented almost 30% of the spend. That is the kind of pattern a cost tracker should make obvious.

What DriveQuery is being built to do

DriveQuery's charging cost tracker is being designed to keep the source data visible rather than replace it with a black-box number. The intended flow is simple:

1. Detect and record the charging session.
2. Keep the energy, time and location context.
3. Apply the most relevant price basis available.
4. Keep billed and estimated amounts distinguishable.
5. Roll sessions into weekly, monthly and custom-period totals.
6. Let you open the total back into the sessions that created it.

The same history can then support budgeting, charging-history export, employer reporting and smarter charging decisions without maintaining a separate spreadsheet for each reporting need.