Why Tesla Charging Costs Less in Wisconsin Even with the New EV Tax

In the new year, we are seeing a 3 cent tax per kWh on charging in the State of Wisconsin. But news this week says that the cost to charge has supposedly been reduced in much of the country. So I decided to do a little research.

What is the effect of the new tax for charging my electric car? What kind of savings can I expect to see if I charge my car in Madison, Wisconsin?

Price Variability by Supercharger

I observed that in 5 out of 6 of my charge sessions the price I had to pay had been reduced or was less expensive. It was good to see, even if only for the short term.

1. Locations with Minor Variability:
   • Lake Delton: The pricing between the old and new models is nearly identical, with a slight increase under the kWh-based model. This indicates that the previous time-based rate aligned closely with the energy consumed during typical sessions.
   • Fitchburg: Only a minor reduction in cost (-12%), suggesting the old rate approximated energy costs fairly well.
2. Locations with Significant Variability:
   • Madison - Whitney Way: A 24% price reduction highlights the savings of kWh-based pricing, especially during peak hours where per-minute costs can be high.
   • Janesville: A dramatic 58% decrease underlines how tiered, time-based pricing disproportionately penalized high-speed chargers for short sessions.
   • Madison - E. Washington: Over 50% savings suggest that longer sessions benefit greatly from kWh pricing.
   • Madison - South Livingston: Nearly 80% reduction reflects the steep cost of short sessions under the old time-based model.

What happens when we factor in the 3-cent-per-kWh tax coming in January 2025?

Here’s a table that shows the price increases for each charging session, comparing the old price (2023) with the new price + tax (2025):

Key Insights:

1. Savings vs. Increases:
   • Most locations show a cost decrease when transitioning to the new model, even with the tax.
   • Exceptions like Lake Delton and Janesville (Tier 4) reflect a slight increase due to energy consumption patterns and usage length.
2. High Savings Locations:
   • Madison (E. Washington) and South Livingston show the most significant savings under the new system, as the previous per-minute charges were higher.

The new 3-cent-per-kWh tax in Wisconsin applies to Level 3 chargers and to Level 1 and 2 chargers installed after March 22, 2024.

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Takeaways

• Short Sessions: Drivers benefit most from kWh-based pricing, especially when charging for brief durations or using high-tier Superchargers.
• Peak vs. Off-Peak: The dynamic rates at Whitney Way further amplify savings for off-peak users under the new model.
• Overall Trend: The shift to kWh-based pricing introduces consistency and fairness, eliminating the disproportionate costs associated with high-speed or short-duration charging sessions.

But here's the good news: any Level 1 and 2 chargers put in before that date, along with existing Level 3 chargers, won’t be affected by the tax in 2025 and beyond.

Charging station operators will only add the tax where it applies, so you can expect some clarity in pricing!

I wondered if once you factor in the changes to Tesla’s charging rate changes and the added three-cent tax, it would cancel out. It turns out it’s cheaper than the old per-hour rates we had. I don’t have a problem paying about the same price while paying the extra green tax.

Tesla Supercharger Pricing Changelog: Wisconsin (2023–2025)

2023 Pricing Model

• Lake Delton, WI: $0.38 per kWh.
• Madison - Whitney Way: $0.49 per minute.
• Fitchburg, WI: $0.25 per minute.
• Janesville, WI: Tier-based pricing:
  • Tier 3: $0.80 per minute.
  • Tier 4: $1.30 per minute.
• Madison - E. Washington Ave.: $0.45 per minute.
• Madison - South Livingston: $1.15 per minute.

2024 Pricing Model (as of December)

Shift to per kWh pricing at most locations for increased transparency:

• $0.35 per kWh at most locations, with slight variations:
  • Lake Delton, WI: $0.36 per kWh.
• Madison - Whitney Way: Time-of-day pricing introduced:
  • $0.30/kWh (off-peak).
  • $0.37/kWh (peak hours).
• Fitchburg, WI: $0.33 per kWh.

2025 Updates (Effective January)

• Introduction of a statewide 3¢/kWh tax.
• Adjusted rates reflect the tax:
  • Lake Delton, WI: $0.39 per kWh.
  • Madison - Whitney Way: Off-peak: $0.33/kWh, Peak: $0.40/kWh.
  • Fitchburg, WI: $0.36 per kWh.

Impact Analysis

• Majority of locations see reduced costs under the new kWh-based pricing model.
• High-cost per-minute tiers replaced with equitable kWh pricing, benefiting users at high-usage Superchargers.
• Example session comparison:
  • Madison - E. Washington Ave. (16 min): $7.20 (2023) → $3.80 (2025).
  • Janesville (Tier 3, 6 min): $4.55 (2023) → $3.80 (2025).