A bidirectional DC charger is a DC charger whose power electronics can move energy in both directions: from the supply into the car’s battery, and back out of the battery as usable AC power. The difference from an ordinary DC charger is not the connector — it is conversion hardware and control software built to run the power path in reverse, under a negotiation with the car.
Key Takeaways
- A bidirectional DC charger runs its conversion in both directions and negotiates discharge limits with the car.
- The capability is designed hardware, not a setting — it cannot be added to a one-way unit later.
- Read every DC charger as one-way unless its documents state “bidirectional” and name the standard.
- EVDANCE’s DC charger is one-way; EVDANCE sells no bidirectional DC charger.
What “Bidirectional” Adds
In an ordinary DC charger, the unit does the AC-to-DC conversion itself and pushes DC into the battery. Running that path backwards demands more than a switch:
- Reversible power electronics. The conversion stage must also turn battery DC back into AC, synchronised with the grid or home supply it feeds.
- Grid protection. Anything that can feed power out has to isolate itself safely when the supply fails, so it never energises lines that should be dead.
- A two-way conversation. Charger and car negotiate the discharge — how much may leave, how low the battery may go — over the bidirectional communication standard, ISO 15118-20. The car, not the charger, sets those limits.
That is why bidirectional DC units are sold as matched systems for specific vehicles, often through the car maker: the charger, the car and the communication standard all have to agree. The family as a whole is set out in bidirectional charging explained.
One-Way vs Bidirectional DC, Side by Side
| One-way DC charger | Bidirectional DC charger | |
|---|---|---|
| Power flow | Supply to car only | Supply to car, and car back to home or grid |
| Conversion | AC to DC, one direction | AC to DC and DC to AC, in the same unit |
| Communication | Charging negotiation | Charging and discharge negotiation, including battery limits set by the car |
| Typical role | Fast charging at homes, depots and public sites | Vehicle-to-home and vehicle-to-grid systems, with the approvals those require |
There is also a second place bidirectional hardware can live: in the car. Some systems keep the inverter on board and discharge through an AC connection. Either way, the spec-reading rule is the same — the capability is a designed, stated feature of a specific system, not a property of DC charging in general.
How to Read a Spec Sheet
Assume a DC charger is one-way unless its documents say otherwise. “Bidirectional” must be stated — in the charger’s specification and in the car maker’s documents for your model — because the hardware difference is real and cannot be added later by software. Then check the pairing: the unit and the car must share the same bidirectional standard, and for grid export the installation still needs the utility’s interconnection approval. Which EVs can do bidirectional charging covers the car side of that check.
Where EVDANCE Fits
Plainly: the EV-RHDC30K-L states no bidirectional capability, because it has none. It is a compact one-way DC fast charger of 22 kW DC with OCPP 1.6J and an IP54 rating, built to charge cars at sites that need DC speed without corridor-scale hardware. EVDANCE sells no bidirectional DC charger; if a project needs discharge, that line belongs to a car maker’s matched system, and the checks above decide the pairing.
Frequently Asked Questions
Is every DC fast charger bidirectional?
No. Almost all DC chargers are one-way. Bidirectional units are a small, specific class, sold for named vehicles and purposes, and the capability is always stated in the documentation.
Can a bidirectional DC charger still fast-charge normally?
Yes — charging is one of its two directions, and outside discharge windows the same equipment charges the car. The discharge side is the addition, not a replacement.
Does a bidirectional DC charger keep working in a blackout?
Not by itself. A grid-export unit shuts down when the grid fails, by design. Powering a home through an outage is a vehicle-to-home system question — transfer equipment and a backed-up panel — which our vehicle-to-home availability check works through.
Related Reading
- Bidirectional Charging Explained: V2L, V2H and V2G
- Which EVs Can Do Bidirectional Charging?
- Is Bidirectional Charging Worth It?
- When Will Vehicle-to-Home Be Available?
