FDF Labs
EV charging station software, in development

Electric-car charging, paid before you plug in.

Software to run electric-car charging stations, in development: the driver's app, the server that talks to the chargers over OCPP 1.6J, and portals for the operator, field technicians and companies with fleets. It is built end to end and runs against virtual chargers that speak the same protocol as real ones. It has not been connected to a real one yet.

CSU1Costanera Sur

  • ACCS2 · 150 kWCharging
  • BGB/T · 150 kWAvailable
  • CType 2 · 22 kWOut of service

A and B share 150 kW: what one doesn't use, the other takes.

A charger from the test network, built from the rating plate and the manual of a BENY BADC172-D fast charger. Each connector's state comes from the charger's own messages: available, charging, reserved, out of service or offline.

One charge, message by message.

The app never talks to the charger. It takes the payment, and the server gives the order over OCPP, the open protocol public chargers use.

CSU1 · Aserver ⇄ charger
  1. → RemoteStartTransactionconnectorId 1 · idTag APP-pelreg0nwzThe payment is already taken. The server asks the charger to start.
  2. ← StatusNotificationPreparingThe connector waits for the cable.
  3. ← StartTransactionmeterStart 3648520 WhCar plugged in. The server opens transaction 81.
  4. ← MeterValues × 63Wh · W · SoC 15 → 81 %Every meter reading is counted against what was paid.
  5. → RemoteStopTransactiontransactionId 81It reached the 80% asked for. The server stops it.
  6. ← StopTransactionmeterStop 3706903 Wh · Remote58.383 kWh delivered.
  7. ← StatusNotificationAvailableUnplugged. The connector is free and the charge is closed.

A real charge in the lab, on 23 October 2026, on connector A of the virtual charger CSU1. It ran in the accelerated test, where a charge takes seconds. Every message gets an answer from the other side; those are left out here.

Pay first. What's left comes back.

No energy flows before payment. The driver picks how much: an amount, some kWh, or up to a battery percentage. At the end, the difference goes back to their balance.

ReceiptCSU1-A · CCS2

Prepaid, up to 80%
Gs 150,000
Energy, 58.383 kWh × Gs 1,750
Gs 102,170
Connection, 5% capped
Gs 5,000
Charged
Gs 107,170
Back to the balance
Gs 42,830
05010015020 %40 %60 %80 % 138 kW 63 kW kW 15 % · 138 kW16 % · 139 kW17 % · 137 kW18 % · 137 kW20 % · 139 kW21 % · 139 kW22 % · 139 kW23 % · 139 kW24 % · 138 kW25 % · 139 kW26 % · 137 kW27 % · 137 kW28 % · 138 kW29 % · 139 kW30 % · 139 kW31 % · 137 kW32 % · 138 kW33 % · 137 kW34 % · 138 kW36 % · 137 kW37 % · 139 kW38 % · 138 kW39 % · 137 kW40 % · 137 kW41 % · 137 kW42 % · 138 kW43 % · 138 kW44 % · 138 kW45 % · 137 kW46 % · 137 kW47 % · 137 kW49 % · 139 kW50 % · 137 kW51 % · 139 kW52 % · 135 kW53 % · 132 kW54 % · 129 kW55 % · 126 kW56 % · 124 kW57 % · 123 kW58 % · 120 kW59 % · 115 kW60 % · 114 kW61 % · 110 kW62 % · 108 kW63 % · 106 kW65 % · 103 kW66 % · 100 kW67 % · 97 kW68 % · 95 kW69 % · 93 kW70 % · 90 kW71 % · 87 kW72 % · 85 kW73 % · 82 kW74 % · 80 kW75 % · 76 kW76 % · 73 kW77 % · 71 kW78 % · 69 kW79 % · 66 kW81 % · 63 kW
The power in that same charge, against the car's battery: about 138 kW up to 50%, then down to 63 kW at 81%. That is the shape of a real fast charge, which the virtual charger imitates.

The figures from that charge, at the demo tariff. The tariff is set per connector in the operator's panel.

For people who drive for a living.

It is designed for people who drive for ride-hailing apps, where every minute parked is money not coming in. The app says where it pays to go now and how long the wait is, and it lets them know.

The app's notifications, translated from Spanish. The line underneath says when each one goes out.

From Asunción to the Chaco.

The test network puts chargers in real towns. The trip planner works out the stops from the real roads and the car's battery.

> 200 km Asunción Ciudad del Este Encarnación Pedro Juan Caballero Filadelfia
Each lit square is a place with chargers. The longest stretch without one, from Benjamín Aceval to Pozo Colorado on the Trans-Chaco highway, is over 200 km.
chargers in the test network
54
places, from Greater Asunción to the Chaco
50

A portal for each of them.

The same data and the same words in all of them: charger, connector, place.

Driver
An app for iPhone and Android: a map of free connectors, a queue with turns, trips with stops, payment by balance, card, bank QR, mobile wallet or express pay, the charge live, and the receipt.
Operator
A panel with the network live, faults and work orders, tariffs per connector, refunds, reconciliation, invoicing and a monthly report. Each role sees its own part, and every change goes into the audit log.
Field technician
Work orders that open by themselves from a charger fault, a complaint or a check-up, with photos and sign-off.
Fleets
A balance shared by the company's drivers, RFID cards to tap on the charger, and invoices with the company's tax number.
Public site
A live map, prices, network status, and a page per connector for whoever arrives through the QR sticker on the charger.

What isn't up for debate.

Rules written into the server, not the screen.

Run a charging network?

Tell us how many chargers you have, which make, and how charging is paid for today.

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