A U.K. Octopus Energy customer sparked backlash online after trying to game the smart tariff system, asking whether slowing an electric vehicle's charging speed could extend cheap daytime electricity for the rest of the home under the tariff's terms.
The goal was to get a longer low-rate charging window to fill a home battery and heat water more cheaply, rather than just top up the car.
Here's what to know
In the Reddit thread in r/OctopusEnergy, the poster described a setup built around Intelligent Octopus Go: a VW ID.3, a home battery, and an immersion-heated hot-water cylinder.
Their concern was that daytime smart-charging slots do more than charge the car, because "the qualifying half-hour periods also give the house cheaper electricity." They said that makes afternoon windows valuable for carrying the battery "through the evening before 11:30 pm."
They said the car's alternating-current charging can be turned down from roughly 7.4 kilowatts to about 2.5 kilowatts. At a lower charge rate, the vehicle would take longer to charge, extending the cheaper home energy.
The poster pointed to Octopus' Smart Tariffs Terms and Conditions and highlighted section 2.3.1.8 in the Intelligent Go terms. The clause quoted in the thread says: "Intelligent Octopus Go is subject to a fair use policy with a maximum of six hours of managed charging per 24 hours."
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Commenters were divided. On one hand, they say the OP is entitled to use what is detailed. On the other hand, they say people who "cheat" the system are why the charge limit was imposed in the first place and worry about further restrictions.
One commenter wrote: "You get 6hrs, how you use is it is up to you."
Another commenter pushed back much more sharply: "And here is exhibit A. The reason why the charge cap was introduced."
More background
The poster said they accepted that slower charging would "use more of that allowance for fewer [kilowatt-hours]" and wanted to know whether the written terms forbid that approach at all.
They wrote that Octopus is "giving us 6 hours of charging per day," with daytime sessions appearing more often because of "real-time grid dynamics, carbon intensity, etc."
"Times are changing. Previously, we have been encouraged to charge overnight, but now the dynamics of the market are encouraging," they said.
The question focused on the home energy cost. The cheaper rate appears to apply across the home during qualifying half-hour windows, not just to the EV. That creates an obvious benefit for anyone trying to charge a household battery or heat water while the lower price is available.
What can be done?
The wording cited in the thread pointed out that the restriction is a ceiling on "managed charging per 24 hours." The poster said they couldn't find any language in that clause requiring a charger to run at a particular minimum speed.
Slower charging stretches time rather than increasing the daily allowance. It may lengthen some cheap-rate household periods, but it also means fewer kilowatt-hours go into the car in those six hours, and a commenter noted there is "no guarantee" of when slots are assigned.
The poster wrote: "If they do want you to charge at maximum throttle (which I don't think is in their best interest at least some of the time they should state that)." Until then, some users appear to be relying on the literal wording of the cap, while others are focused on what they see as the tariff's intended purpose: charging an EV, not maximizing discounted electricity for the entire house.
As one commenter put it: "It's against the spirit of it, but I don't think it's explicitly against the terms to use a slower than 7.4kW charger."
Where can I learn more?
These stories show how the tariffs can create confusion, opportunity, and frustration for EV owners and households.
• A U.K. EV owner said cheap afternoon charge was later billed at peak rates.
• An Octopus customer used a two-hour happy hour for a roast, laundry, and EV charging.
• In the U.K., one Tesla owner saw Powerwall charges at 30 pence on Octopus, not 7 pence.
• A U.K. homeowner asked what five cheap hours buys with an EcoFlow battery.
• Across the U.K., battery owners called off-peak charging a no-brainer even without rooftop solar.
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