Payment Flow

Thorium uses a preauthorization-based payment model powered by Viva Wallet. This means drivers are never overcharged — they pay only for the exact energy they consume. This page explains every step of the payment lifecycle, from the initial card tap to the final bank settlement.

Why Preauthorization?

EV charging is an open-ended transaction. Unlike buying a coffee where the price is known upfront, a charging session's final cost depends on how much energy the vehicle draws and how long the driver chooses to stay plugged in. Preauthorization solves this elegantly:

The driver's bank holds a fixed amount when they tap their card.
Charging begins immediately — no need to predict the session cost in advance.
When the session ends, only the actual cost is captured from the hold.
The unused portion is released back to the driver automatically.

This is the same model used by petrol stations, hotels, and car rental companies worldwide.

Step-by-Step Payment Flow

1. Card Tap (Preauthorization Request)

When the driver taps their contactless card, phone, or wearable on the Viva Wallet NFC POS terminal, Thorium initiates a preauthorization request. The default preauth amount is 30.00 EUR, which covers approximately 100 kWh at the default rate of 0.30 EUR/kWh. This amount is configurable by the operator.

2. Hold Confirmation

Viva Wallet communicates with the driver's issuing bank. If the card has sufficient funds and the bank approves the hold, Thorium receives an authorization code. The held amount appears as a "pending" transaction on the driver's bank statement. No money has actually moved yet.

3. Charging Session

With the preauth confirmed, the contactor closes and power flows to the charger. Thorium monitors the running total. If the accumulated cost approaches the preauth limit (within 90%), the system will warn the driver on the touchscreen and prepare to end the session gracefully.

4. Session End

When the session completes (driver unplugs, preauth limit reached, or operator stops), Thorium calculates the final energy consumed and the corresponding cost.

5. Capture

Thorium sends a capture request to Viva Wallet for the exact session cost. For example, if 8.2 kWh were delivered at 0.30 EUR/kWh, the capture amount is 2.46 EUR. This is the actual charge that will appear on the driver's bank statement.

6. Release

The difference between the original preauth hold and the captured amount is released automatically. In the example above, 27.54 EUR of the original 30.00 EUR hold is released back to the driver.

Release timing varies by bank. Most banks release the held funds within 1–3 business days. Some banks may take up to 7 days. This is controlled entirely by the driver's issuing bank, not by Thorium or Viva Wallet.

What Happens If the Preauth Amount Is Exceeded?

Thorium is designed to prevent this from happening. The system continuously tracks the running session cost against the preauthorized amount. When the cost reaches 90% of the preauth limit, the touchscreen displays a warning. At 95%, the session is automatically terminated and the contactor opens.

In the extremely unlikely event that a capture exceeds the preauth (e.g., due to a communication delay), Viva Wallet will attempt to charge the full amount. If the card cannot cover it, the difference is handled through Viva's standard dispute resolution process.

Refund Timeline

Event	Timing
Card tap (preauth hold placed)	Instant
Session ends, capture sent	Within 5 seconds of session end
Capture appears on bank statement	1–2 business days
Unused hold released to driver	1–7 business days (bank-dependent)
Funds settled to operator's Viva account	Next business day (T+1)

Viva Wallet Integration Details

Thorium integrates with Viva Wallet through a combination of the physical NFC POS terminal and Viva's cloud API:

NFC POS terminal — handles the physical card interaction (tap, chip, PIN if required). Connected to the Thorium controller via USB.
Viva Wallet API — used for preauthorization, capture, void, and refund operations. All API calls are made server-side from the Thorium controller over HTTPS.
Merchant account — all captured funds are deposited directly into the operator's Viva Wallet merchant account. There is no intermediary. Thorium and Dark Matter Networks never touch the funds.

Zero commission. Thorium does not take any percentage or fee from transactions. The only payment processing fees are Viva Wallet's standard merchant rates, which are agreed upon directly between the operator and Viva Wallet when setting up the merchant account.

Setting Up Viva Wallet

To use Thorium's payment functionality, operators need an active Viva Wallet merchant account. If you don't already have one, you can apply at vivawallet.com. Once your account is approved, contact us at [email protected] with your Merchant ID and we will pair your Thorium unit to your account.