Joulary
Free app for Tesla owners
Charge your Tesla when Agile prices are low
Joulary plans your home charging up to two weeks ahead and tells you when to plug in. It can also warm the car before a trip in your calendar.
If you're on Agile today
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Checking prices every evening
Octopus publish the next day's prices at about 4pm. Joulary picks them up within a few minutes, uses the AgilePredict forecast for any times Octopus haven't published yet, and updates the charging plan when either changes.
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A charger set to "charge below 10p"
A charger with a price limit starts whenever the price drops below it, even when the car is already full enough, and never starts if prices stay above it. Joulary starts from what you need: how much charge, and by when. Then it picks the cheapest half-hours that get you there.
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Home Assistant or a spreadsheet
You don't need a hub, scripts or a smart charger. You connect your Tesla and your Octopus account in the app, and Joulary sends its charging commands straight to the car.
It plans several days ahead
Until Octopus publish the real prices, Joulary uses price forecasts from AgilePredict, with x2r and agileforecast.co.uk as back-ups. That lets it wait for a cheap Sunday lunchtime when it would otherwise have charged at Tuesday night's higher rate. When Octopus publish the real prices, the plan updates.
Tap any charge on the chart to see why it was booked: for a trip, for one of your charge targets, or because the price was low.
It tells you when to plug in
You get a reminder only when the plan needs the car plugged in. For an overnight charge it arrives an hour before your bedtime, while you can still get to the car. For a charge during the day, it arrives shortly before charging is due to start.
Joularynow
Plug the car in
Plug in so charging can start at 23:30
Charge targets and calendar trips
A charge target is a weekly goal, such as 80% by 07:30 on weekdays. For each upcoming one, you can tell Joulary how likely you are to need it, and it plans less charge for the ones you are less sure about.
You can also add /car to a calendar entry that has a place and a time. Joulary works out the
drive, using your own past trips to the same place when it has them, and makes sure the car has enough
charge before you leave. Entries close together are planned as one trip.
A warm car before you leave
When a trip in your calendar starts within three hours and the cabin is far from the temperature set in the car, Joulary turns the climate on before you leave. It learns how long your car takes to warm up or cool down, and starts that long before you set off.
On a mild day it leaves the climate off. If you have already turned the climate on yourself, Joulary leaves that trip to you.
What it saved, compared with Intelligent Octopus Go
Every day, Joulary works out what your electricity cost on Agile and what the same electricity would have cost on Intelligent Octopus Go, the Octopus tariff for electric cars. It shows the house and the car separately. For the Go figure, it moves your car's charging into Go's cheap overnight hours, as Go itself would.
If Go would have been cheaper, the app shows the difference in red.
In the year shown here, charging the car cost 7.9p a unit on Agile and would have cost 7.8p on Go. The saving of £246.26 came almost entirely from the rest of the house, which paid 21.1p a unit on Agile instead of 25.7p on Go.
Help from an assistant that can see your plan
You can ask the built-in assistant a question such as "why isn't my car charging tonight?". It looks at your charging plan, your prices and what your car last reported, and it knows which screen you asked from. When an answer draws on the Manual, it lists the pages it used.
- Each answer must be based on the Manual or on what your own screens show. If the assistant can't find that basis, it says it can't answer.
- If you ask from the Timeline, the answer is about the Timeline: the charge that is booked, its price and why it was booked.
- The assistant isn't told your location, the titles of your calendar entries, the names of your charge targets, or any password or access key. It can't change your settings or start a charge.
- If you need a person, Contact support is on the same screen. You decide whether your conversation with the assistant goes with your message.
The assistant is off until you turn it on. While it is off, nothing about you is sent to the AI provider.
Settings for people who like to fine-tune
Extra charge when it's cheap
When electricity is at or below your Yummy price, Joulary charges beyond what you need, up to a limit you set. It never does this at the expense of charge a trip needs.
Battery health
Charging past your Super yummy max battery level on very cheap electricity is limited by an allowance you set, and only happens when a trip will use the extra. If a long trip needs a full battery, Joulary charges to 100% as close to the time you leave as it can.
It learns your car
Joulary measures how fast your car charges at home, how much battery a mile takes and how much it loses while parked. The figures come from your own charging and driving, and keep up as the seasons change.
Minimum charge
Set Keep charge higher than, and how long the battery may stay below it. If it drops below, Joulary tops it up at the cheapest time within that period.
Charge now
Start a charge straight away, to the level you choose. Smart charging takes a break while that charge runs, then takes over again, or straight away if you tap Resume smart charging.
Short Term mode
If you don't want the long-range plan, choose a level and a time, such as 80% by 07:00. Joulary charges in the cheapest half-hours before then.
Your calendars
Connect Google Calendar, Apple iCloud or both. Joulary treats only the entries you have tagged as car trips.
Reminders that fit your day
Set your bedtime, your wake-up time and how much notice you want. Plug-in reminders are timed around them.
Designed to be dependable
- Your Tesla sends changes to Joulary as they happen, such as plugging in, starting to charge or turning the climate on. They arrive within about a second, so Joulary doesn't need to keep waking the car to ask.
- While Joulary is still working out a plan, for example while it waits for prices, it leaves any charge that is already running alone.
- If prices can't be fetched from Octopus for a while, Joulary keeps planning with the last prices it had and the forecast.
- Sometimes a car stops charging early because an old charge limit is still set. Joulary raises the limit and starts the charge again.
- When something needs your attention, such as a charge it can't finish in time or a Tesla sign-in that has expired, Joulary tells you in plain words.
What you need
- A Tesla. Your Tesla account needs to have just one car on it.
- An Octopus Energy account on the Agile tariff.
- A way to charge at home. Any charger works, including a three-pin cable, because Joulary sends its commands to the car.
- A Google or iCloud calendar, if you want trips planned for you.
Your data
Joulary uses a read-only access key from your Octopus account. You can remove its access to your Tesla at any time in your Tesla account. For each drive it keeps where and when the drive started and ended, the battery level at each end and the distance, but not the route or your speed. You can download or delete all your data from the app, and the privacy notice has the details.