VoltGarage
EV charging log and cost calculator
Every charge is a layer in your battery.
VoltGarage is a charging and cost log for electric cars, on Android. It records every charge, at home, at work or at a station, and works out what you pay per kilometre.
Driving uses the leftmost, oldest layer first.
Energy keeps the colour of where it came from.
A kWh can cost several times more at a fast charger than at home. Without knowing how much of the energy in your battery came at which price, you cannot know your cost per kilometre. VoltGarage keeps track of it for you.
Add charge
Pick where you charged and enter the start and end percentage. If you do not know the price, the community price is suggested.
A layer appears
The charge is added to the battery in the colour of its source. Expensive energy looks brighter.
Driving uses it up
As you drive, the oldest energy goes first. Add your odometer reading and you get your cost per kilometre.
EV charging cost calculator
Enter your own numbers. The length of each bar is the money you pay, both on the same scale.
Assumptions: the electric car uses 18 kWh per 100 km, the petrol car 7 litres per 100 km. A 10% charging loss is included, so you pay for 110 kWh for every 100 kWh that reaches the battery. Starting prices: for the euro, Eurostat household electricity (first half of 2026) and the EU Weekly Oil Bulletin (12 October 2026), medians across euro countries; for the US dollar, EIA figures (electricity July 2026, petrol 12 October 2026). Fast-charging prices are typical examples. This is an estimate; the app works out your real figure from your own charges.
Inside the app.
Beyond charging.
Live charge tracking
Tap "I plugged in" and it works out when you will be full and notifies you when it is done.
World station map
Stations from OpenStreetMap and Open Charge Map, with prices entered by drivers.
Add a new station
Missing from the map? Drop a pin on it. Once 10 different people confirm it, everyone sees it.
Expenses and reminders
Servicing, tyres, insurance, inspection. Your phone reminds you when it is due.
Backup without an account
No sign-up. Your entries are backed up and move to a new phone with a recovery code.
Trip cost
See how many kWh and how much money a trip needs, and how many stops.
Switch from Drivvo or Fuelio
Import your old entries from a CSV file. Exporting is always free.
Start free. Go Pro if you need it.
Free
Shows ads.
- 1 car
- All entries kept, last 3 months shown
- Live charge tracking
- World station map
- Community prices
- Backup without an account
Pro
Monthly or yearly subscription, cancel any time in Google Play.
- No ads
- More than one car
- Full history
- Spend by network and battery health report
- Share your report as a PDF
VoltGarage at a glance.
- What it is
- A charging and cost log for electric cars. It keeps every charge as its own layer in the battery and works out your cost per kilometre.
- Platform
- Android, on Google Play. Not released yet, coming soon.
- Price
- Free version: 1 car, with ads. Pro: monthly or yearly subscription.
- Account
- Not needed. You move to a new phone with a recovery code.
- Your data
- On your phone, backed up over an encrypted connection to our server in the European Union. Receipt photos are never sent to our server. Details: Privacy.
- Stations
- OpenStreetMap and Open Charge Map data, prices from drivers.
- Languages
- English and Turkish.
- Publisher
- OWL APP LTD, a company registered in England and Wales (16945604).
- Contact
- contact@owl-app.com
Common questions.
How much does it cost to drive an electric car 100 km?
Take the kWh the car uses per 100 km, multiply by 1.1 (about 10% charging loss), then by the price per kWh. If your car uses 18 kWh per 100 km, you pay for 19.8 kWh. At €0.24 per kWh at home that is about €4.75; at a fast charger asking €0.59 it is about €11.68. A petrol car using 7 litres per 100 km pays about €13.51 at €1.93 a litre. These are the calculator's starting prices; try your own numbers above.
How does VoltGarage work out cost per km?
For each charge it divides what you paid by the kWh that went into the battery, which gives that charge's price per kWh. As you drive, the energy used is taken from the oldest layer first and divided by the distance between two odometer readings. So your cost per km comes from the price of the energy that trip actually used. Worked example: how EV cost per km is calculated.
Why is the oldest energy used first?
Because the energy in your battery may have come at very different prices. If you charged cheaply at home and then topped up at an expensive fast charger, the next trip uses the home energy first and the fast-charge energy after it. The battery does not really keep energy apart; this is an accounting method (first in, first out). It puts the cost of a fast charge on the trips that used it instead of spreading it over all of them.
Is VoltGarage free?
There is a free version: 1 car, all entries kept, the last 3 months shown in lists, with ads. Pro is a monthly or yearly subscription. It removes ads and adds more than one car, full history, spending by charging network, a battery health report and PDF reports. You can also earn points with station reports and unlock a month of Pro. Exporting your entries is free in both.
Do I need an account?
No. The app does not ask for your name, email or phone number. Your entries stay on your phone and are backed up over an encrypted connection to our server in the European Union. When you move to a new phone, you enter the recovery code from Settings.
Where do the charging stations and prices come from?
Stations come from OpenStreetMap and Open Charge Map data. Prices are entered by drivers and shown in each country's own currency. If a station is missing, you can add it: once 10 different people confirm it, everyone sees it, marked "Confirmed by the community".
Can it tell me when charging will finish?
Yes. Tap "I plugged in" and it estimates when the battery will be full, then notifies you when it is done. If you pick your car's Bluetooth, it asks whether you plugged in once you park and the connection drops. Tracked charges teach it your car's real charging speed.
Can I bring my entries over from Drivvo or Fuelio?
Yes. Import the CSV file you export from Drivvo or Fuelio. Exporting your entries from VoltGarage is always free too.
Is it on iPhone?
Not yet. VoltGarage is being built for Android and will be on Google Play. The app is in English and Turkish.
Which countries does it work in?
The station map covers the whole world, and community prices are kept in each country's own currency. In some countries it also shows the national average price of home electricity and petrol.
Coming to Android.
Once it is out, this page will take you to Google Play.
Google Play coming soon