How we came to our charging station?

Well, cars are since ever a hobby. When we bought our house in Thalham 2013, we finally got the opportunity to use our property for a car hobby. Our "gazoline guzzler" (a 79 Oldsmobile Starfire V8) found its way quickly into our garden. But beside of that we developed the idea to commute to work (50 km one way) with an electric vehicle.

The cars that are on the market for a reasonable price have a range of about 120 km in the winter (2014). Those cars would be capable for the daily travel. So we now only just needed to read a bit about charging technology ...

Well, only ... We found out, that this is quite a study. Lets just stay with the European standard technology.

Typ 2 is the magic word. The idea is simple. When you want to charge different vehicles at one station, you have to consider the different charging capacities of the vehicles and the different abilities of the cables used. How can you make all that "understandable" for a charging station?

The technical marvel that exchanges the information about the cable and the car is called a "pilot". This is the most expensive part of the wallbox and costs about 350 Euro. The rest inside the wallbox ist common heavy current technology, except the socket. The socket is normed and is called "Typ 2". The cable has Typ 2 plugs and communicates his maximum Ampere capability over a little resistor.

At a common private household in Germany, a wallbox can deliver a maximim of 380V, 32A. The pilot can regulate down to 200V, 16A if needed.

What does this mean for charging times? A Renault ZOE uses a "Chameleon" charger, that charges tri-phase up to 63A. This is where the wallbox says "I can do only 32A". The charging capacity of a ZOE is 22 kWh. 380V, 32 A makes also 22 kW. So a ZOE should be fully charged within one hour. "Should", because the charging system of the ZOE reduces to 16A at the end of the charging, to protect the batteries. This makes then a charging time of about 1.5 hours. Acceptable for a nice walk around the lake, fishing, or a tennis match.

The Renault Fluence Z.E. is a different story. The Fluence also uses 22 kWh batteries, but can only charge with 220V, 16A (makes 3.7 kW). He uses a Typ 1 plug. At 3.7 kW a Fluence takes 6-8 hours to fully charge his 22 kWh.

It became clear, that a Typ 2 wallbox with 380V and 32A was the best decision for use in a private household. What car to buy, is a whole different story ...

We got loads of valueable information on all this at the forum www.goingelectric.de/forum.

After it was clear, what wallbox to buy, we got lucky on a bargain Walther e-Boxx at Ebay. Very cool, so now we could start.

We wanted to connect the wallbox with the internet. When an EV would charge, a notice should be published on the website and we wanted to have an email about the start and the end of the charging procedure. A smart little project.

More about the used hard- and software at links on the left. The source code of the software is also published there.