EV Fleet Charging Strategies: Impatient vs Smart

The value of optimising an EV fleet charging strategy can be huge. Smart charging can reduce energy supply costs by over 63% compared to impatient/dumb charging.

Often there’s an operational preference for charging vehicles to full as soon as they return to the depot at the end of a shift. That’s a natural enough approach, but is it the best way to do it?

To explore that further, we’ve used Gridcog to model the charging costs for four EV fleet depots across Australia’s east coast, testing three alternate charging strategies:

Impatient charging: just charge the EVs to full as soon as you can after they return to base.

Smart charging: optimise the charging such that it only occurs when energy supply costs are cheapest, whilst still ensuring sufficient charge to do the job.

Adding V2G: extends the smart charging scenario but now looks to discharge energy from the EVs to further improve the financials when it makes sense to do so. Again, we still need to ensure the vehicles have sufficient charge for their next shift.

The Model

• We have a small fleet of 8 rubbish trucks each with a battery capacity of 300kWh and a daily energy requirement of 250kWh on days the trucks are operating. It’s a similar vehicle to the eCollect from Dennis Eagle UK that’s widely in use around the world.
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• The fleet is out at work from 5am to 3pm Monday to Friday and consumes 564MWh per year.
  
• The depot has 5 x 100kW chargers.
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• The depot’s grid connection allows max import and export of 500kW
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• The depots are directly exposed to the wholesale energy price for their NEM region using 2024 prices and also incur charges for use of the distribution network against the relevant network tariff for their DNSP.
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• Capex costs are ignored, this is just focusing on potential value. In reality, there will be additional costs associated with enabling V2G.
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• The project mode is for a single year.

The Results

We’ve included annual charging costs for each depot for each scenario broken down by wholesale energy vs network, as well as an average weekly charging profile for the Sydney depot to show you how the simulation is built up in Gridcog.

• Lowest costs with Impatient Charging: Melbourne $169k
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• Highest costs with Impatient Charging: Sydney $235
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• Biggest savings from Smart Charging: Sydney $143k
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• Biggest savings with V2G: Brisbane $110k

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Gridcog software is used to model some of the biggest fleet electrification projects in the world. If you’d like help modelling your fleet projects then drop us a line.

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