ᐅ Electric Vehicle – Bidirectional Charging: The Next-Generation Battery Storage

Hello everyone,

I am going to buy a new car this week. This time it will be an electric vehicle.

The choice will be between the VW ID.5 GTX and the Audi Q4 e-tron 50 quattro.

During my research, I found out that the ID.5 has a really cool and new feature for EVs: the 77 kWh (84.2 kWh) battery can be charged and discharged bidirectionally. This means the ID.5’s battery can serve as a storage system for self-generated solar power from photovoltaic panels. That’s pretty brilliant!

Has anyone here looked into this in more detail and can share some insights?

And maybe we have some car enthusiasts here who know whether the Q4 e-tron is equipped with the same technology?

Since both the ID.5 and the Q4 e-tron are manufactured in Zwickau and are largely similar, does this also apply to the battery technology?

If this really works reliably, in my opinion, it would be another milestone toward even greater energy independence!

I’m looking forward to the discussion…

Bidirectional charging is a great concept, but it is not yet feasible at the moment.
- The regulatory requirements are not yet in place (V2G, V2H).
- Charging stations capable of this are very expensive.
- What about the battery life due to the increased charge and discharge cycles?

All in all, still something for the future.

Michilo schrieb:

Bidirectional charging is a great idea, but currently not feasible.
...
- How does the increased charging and discharging cycles affect battery lifespan?

This is exactly the problem:

Depending on the charging and discharging method, temperature, and electrode design, lithium-ion batteries usually last about >500 full cycles (defined as approximately 70% remaining capacity). Partial cycles extend this lifespan accordingly.
If one were to fully use bidirectional charging—for example, operating a daily storage system that charges from solar power during the day and discharges at night—then the battery would already be considered worn out after about 1.5 years, without having driven even 1 km (0.6 miles).
Replacement generally costs more than 10,000 €.

Everyone has to decide what matters most to them.

Unfortunately, VW is still very tight-lipped about the details – the feature is also supposed to be available for ID.4 models via a software update, so I’m very interested in this as well and can easily imagine using mine for it.

In theory, there is a standardization for Vehicle-to-Grid as ISO 15118-20 (draft), which, according to the manufacturer, can be retrofitted for the openWB Pro via a software update. The charging station itself costs a bit more but is still relatively affordable.

However, everything suggests that the VW implementation will require a DC charging station – which can be quite expensive, currently starting at just under 10,000 euros (around 10,000 USD), and that without V2G support.

Hopefully, VW has something in mind and will offer a more cost-effective solution than the ID.Charger.

Bidirectional charging is a bit of a tricky subject.

- Battery wear
- DC technology required at home (cost?)
- As far as I know, not allowed by regulation in Germany
- VW announced it for 2022, but whether and when anything will actually come… so far they haven’t exactly impressed with their software

DaSch17 schrieb:

Meaning: the ID 5’s battery serves as a storage medium for self-generated photovoltaic power. That’s pretty brilliant!

Prioritizing charging with your photovoltaic power is not a big deal and is possible with the right equipment (charging station, home electrical system). But you can’t really feed it back out, at least not into the building’s electrical grid. For example, the Ioniq 5 can use an adapter to charge small loads and other electric vehicles, but relatively slowly. For the e-scooter in the trunk, the e-bike on holiday, or emergency power, though, that’s definitely quite handy.

We recently discussed this topic here. It sounds like a great idea when you read about it or hear someone rave about it. But in practice, it unfortunately doesn’t live up to the expectations.