# [Tagging] charging station power output

lucas-osm at use.startmail.com lucas-osm at use.startmail.com
Fri Mar 10 18:23:04 UTC 2017

Hey guys,

two of the criteria on charging stations that matter the most to the drivers are the max. power output of the whole station and the max. power output of the socket compatible with my car. The power output of a specific socket gives some orientation on how fast you can charge in the best case. Regardless of other cars charging simultaneously or the battery’s charging level.
It’s useful to know the max power available for the whole station, because this power will be shared among all sockets. So for example if one station only got one socket, these values would be equal. But if you have one with three sockets, your current charging power does not only depend on the sockets max, but also on the total power available.
That’s why these readings should be directly or indirectly available through calculation.
Calculating the max. power is really easy. You just need to know the max. amperage (I), the max. voltage (U) and the number of phases (#np) the current is delivered in (do you say that?).
p = square_root(#np) * I * U
So a normal Schuko socket would give us roughly square_root(1) * 16A * 230V = 3,7kW at best. A Schuko always operates on one phase. So you could say that’s great, we can determine the phases just by looking at the socket type. But sadly there are sockets which can operate at one or three phases. For example the Type2. Just by looking at this one you are not able the tell how many phases are in use. That’s a problem.
Theoretically say there would be a tag specifying the phase count, at least for those with unclear count (assumed we could find this on the station somewhere), there would be another issue: The Type2 socket can not only operate on direct current (DC) or alternating current (AC), but also on both simultaneously. I guess DC and AC will not operate on the same amperage / voltage.
This is getting really messy. As a driver you do not have to worry about the max. voltage or max. amperage one station is able to provide at a socket to determine if you are able to use and charge at a specific station. Because Type2, Type2 Combo etc. all ask your car via pulse-width modulation about it’s limits. If you’ve got the right socket or an adapter, only the maximum charging speed (depends on power output) matters.
I hope the above was not too confusing. If something in this explanation is somehow unclear to you please tell me.

That’s why I’d propose to add a tag describing the power output of the whole station and every single socket.
Obviously the power=* tag is no potential candidate, because it’s already in use “to identify facilities and features that relate to the generation and distribution of electrical power including power lines, power generation ...”.
So what else could we use? Generators already use generator:output=* to classify their output in Watts.
What about adopting this scheme like charging_station:output=* to specify the max. power output of the whole station, distributed over all available sockets. And socket:[socket_type]:output=* to specify the max. power output of one specific socket.

An example:

charging_station:output=98kW
socket:type2:output=43kW
socket:type2_combo:output=50kW