Prices published daily
Octopus sets a new electricity price every half hour, and posts tomorrow's prices around 4pm. Ember picks them up the moment they land and starts working out when to charge.
Octopus Agile · Tesla · iPhone
Charge your Tesla in the cheapest window.
Ember reads every half-hourly Agile price, finds the cheapest window for your battery, and charges your car automatically. You just plug in.
A day on Agile
Prices swing all day. Ember waits for the bottom.
p / kWh, half-hourly
Live today
00:0006:0012:0018:0000:00
Cheapest window · 02:00 to 04:30 · ~3p/kWh
Octopus Agile prices update every 30 minutes. Ember reads them the moment they publish and charges your Tesla in the cheapest contiguous block that reaches your target. Not a fixed window. Yours.
How it works
Three steps. Then you stop thinking about it.
Your window, calculated
Ember finds the cheapest stretch of hours that will charge your Tesla to the level you want, based on how full the battery is right now. Not a fixed window. Yours.
Tesla charged. You do nothing.
Ember starts the charge when that window begins and stops it the moment you hit your target. When it's done, you get a notification with exactly what you saved.
The numbers
Real windows. Real savings.
Sub-zero
The most negative window Ember has automated, per kWh
Hundreds
Projected saving per driver, per yearProjected from each driver's actual saving versus their previous tariff rate, annualised from their charging history so far. An estimate, not a guarantee.
~370
Plunge-price windows in the 12 months to April 2026
30 min
Agile's half-hourly pricing resolution
Figures based on Octopus Agile data and Ember session history. Typical saving compared against a 15p/kWh flat-rate baseline. Individual results vary.
It charges the car. You don't.
Ember talks to your Tesla directly and runs the charge for you, starting and stopping it so the energy lands in the cheapest window. No reminders, no fiddling with schedules. Just plug in.
It plans tomorrow before you do.
The moment tomorrow's Agile prices land, around 4:20pm, Ember picks the cheapest window and confirms the schedule. You go to bed knowing exactly when the car will charge.
Every session, tracked
Cost, saving versus your flat-rate tariff, energy delivered. Every charge logged. Your cumulative saving grows in real time.
Pricing
Free to start. Premium to automate.
Free
£0
No credit card. Free forever.
- +See the cheapest charging window every day
- +Full Agile price charts for today, tomorrow, and yesterday
- +Live battery, range, and charge status for your car
- +A daily notification when tomorrow's rates land
Premium
£3.99per month
or £38.99 per yearBest value
- +Fully automatic charging. Ember starts and stops your car at the cheapest slots with zero input from you.
- +Smart notifications. Know when to plug in, and see exactly how much you saved when charging finishes.
- +Recovery windows. Missed your slot? Ember finds the next cheapest one left in the day.
- +Max Range mode. Need a full charge? Ember targets 100% using the cheapest available slots.
- +Skip a charge. Window too expensive or away from home? Skip the day with one tap.
- +Savings analytics. Every session tracked, with your cumulative savings over time.
Both plans live in one app. Download Ember free, then upgrade to Premium any time from inside the app.
Ember is live on the App Store.
Free to download. Connect your Tesla and your Octopus Agile account, and Ember charges in the cheapest window for you.
iPhone only. Requires a Tesla and an Octopus Agile tariff.