Why the cheapest charger may cost a Cybercab owner more

A charger offering electricity at 30 cents per kWh looks more attractive than one charging 45 cents. For a vehicle buying 40 kWh, the difference is $6.

For a working Cybercab, that saving has to survive the journey to the charger, any queue and the time needed to return to service. If the cheaper stop keeps the vehicle away from paying passengers for longer, the owner could finish the day with less money.

The useful comparison is the charging bill together with the change in what the vehicle can earn. That can favor a nearby charger during a busy period and a cheaper, more distant option when demand is quiet.

The following example uses hypothetical prices, energy consumption, charging times and owner earnings. It assumes two compatible charging options are available and permitted under the vehicle's operating arrangement. Actual Cybercab charging access, handling requirements and owner control over charging decisions would need to be confirmed.

Imagine two plans that start from the same location and return to the same service area with the same usable battery energy. The nearby option has a higher electricity price. The cheaper option requires eight additional miles of empty travel and a longer wait.

Assume the extra travel requires two additional billed kWh, including the associated charging losses. Also allow 10 cents per additional mile for maintenance and tires. These are planning assumptions for the comparison, with electricity measured on the billing side of the meter.

Charging and handling durations are assumed for each option, including the electricity purchased. They are not measured Cybercab performance. The example assumes no separate session, parking or service fees and holds other costs equal.

The cheaper site saves $5.40 on electricity. After the extra mileage allowance, the direct cost advantage is $4.60. It also keeps the vehicle unavailable for 40 additional minutes.

Whether that trade works depends on what those minutes are worth.

Suppose the nearby option would allow the vehicle to generate an expected $12 of additional owner contribution per available hour during that period. Contribution means owner receipts after network deductions, less the costs caused by the additional rides, including their energy, mileage and support costs. Assume that work, including any resulting charging needs, fits the rest of the day's schedule.

At that assumed rate, 40 extra minutes of availability are worth $8. Choosing the cheaper charger gives up that opportunity to save $4.60. The owner's modeled result is therefore $3.40 worse for that stop.

The electricity receipt still shows a saving. The difference appears in the combination of operating expenses and earning opportunity.

Saving time has value when that time can realistically produce additional income.

The $12 assumption should reflect the actual period affected, including the likelihood that the vehicle would spend some of that time waiting for a passenger. A busy Friday evening and a quiet weekday morning can justify very different estimates.

Insurance, scheduled loan payments and other fixed obligations still matter to the overall business. If they are unchanged by the charging choice, however, the comparison turns on the additional receipts and costs each option creates.

Using the same charging example, the decision changes as the expected contribution from extra availability changes:

Under these assumptions, the switching point is $6.90 per available hour. That is the $4.60 direct saving divided by the extra 40 minutes, expressed in hours.

If the additional availability could produce more than that amount per hour, the nearby option wins. If the vehicle would otherwise be idle, the cheaper option retains its direct cost advantage.

This is the practical meaning of opportunity cost. The amount depends on a credible alternative use of the vehicle during the specific time affected. Our article on why Cybercab profit depends on vehicle time explores that relationship across the working day.

A useful charging plan should therefore consider location and timing together. A cheaper site might already be close to the end of a passenger trip, making its additional travel small. It might also fit a period when the vehicle is deliberately out of service, provided charging finishes before the next planned operating window.

Conversely, a low priced site across town could pull the vehicle away just as local demand strengthens. The location where charging ends matters too. Returning with more battery energy is useful only if the vehicle can then reach suitable work within the remaining schedule.

This is why an annual average electricity price tells only part of the story. The same price can accompany very different travel distances, queues and availability.

The duration of the charging session also needs its own assumption. A site's advertised maximum power does not establish how quickly a particular vehicle will complete a stop. Tesla's Supercharging guidance identifies battery charge level, battery temperature and other conditions as factors affecting charging speed. It also explains that charging slows as the battery fills. Tesla Supercharging guidance

For planning, use the energy the vehicle needs and a defensible estimate of the complete stop. A shorter session might restore enough energy for a useful operating period. A longer session might avoid another trip to a charger later. Compare the full day's charging pattern, including repeated travel and queues, before deciding which approach costs less.

Queues introduce uncertainty as well as delay. A site that usually has a short wait could occasionally keep the vehicle unavailable much longer. Test a normal stop and a difficult stop, especially if a delay would push charging into a valuable operating period.

A queue normally consumes vehicle time even when it produces no separate invoice. Fees are another part of the calculation. Tesla currently describes congestion fees that can apply at busy Supercharger sites under specified charging conditions. Any fees applicable to the proposed arrangement belong in the direct cost comparison. Tesla Supercharger fees

The displayed energy price also needs to match the intended session. Tesla notes that prices can vary by location and that some sites have different prices at different times. Check the relevant site's pricing terms when building a plan. Tesla Supercharging pricing information

For a private charging arrangement, include the costs of making that electricity usable. Equipment, installation, site access, parking and applicable electricity demand charges can affect the result. A low utility energy rate can still be attractive, but it needs to be evaluated alongside those costs and the number of charging sessions sharing them.

The unit used for energy matters as well. Electricity purchased and energy added to the battery can differ because of charging losses and other consumption. Establish where the energy is measured and use that same basis for the price. In the worked example, the 40 and 42 kWh figures are explicitly billed quantities, so an additional charging loss multiplier would count the assumed losses again.

When comparing complete business scenarios, keep the accounting consistent. The example above uses forgone contribution to explain the value of time. A full operating model can instead reflect that effect through fewer completed rides, lower owner receipts and the associated reduction in variable ride costs.

If the scenario already reflects those lost rides, adding the same forgone contribution as another expense would count the effect twice. Similarly, include charger travel once in total mileage, and distinguish vehicle waiting time from any paid handling work or unpaid owner time.

The broader cost categories are covered in Cybercab operating costs explained.

To test a charging plan in CabOS, save separate scenarios for the alternatives you want to compare:

• A nearby charging option with its energy price, travel and expected waiting time.
• A cheaper option with the additional mileage, energy and time it requires.
• A difficult charging day with a longer queue or slower session.

Check whether the planned passenger activity still fits after charging, travel and other unavailable time. Review the cash flow and economic results alongside that time budget. Demand during specific hours and actual queue behavior need separate assumptions, since CabOS does not simulate dispatch by time of day.

For an owner whose network or service provider controls charging, the same comparison can help evaluate the arrangement. Confirm who pays for charging travel and handling, how charging downtime affects compensation, and what service the quoted price actually includes.

Choose the charging plan that leaves the vehicle ready for worthwhile work at a sensible total cost. A few cents more per kWh can be justified when it preserves valuable earning time. During a quiet period, the cheaper stop may be exactly the right choice.