High-Performance Charging Cable and Connector (Plug, Socket)

First of all: the development of a high-performance charging cable only makes sense with the simultaneous development of a corresponding connector. This plug, in turn, needs a coupling or socket - collectively referred to as a "connector" or power connection.




In order to achieve comparable performance in terms of range and tank or charging speed in electric mobility as in the case of internal combustion engines, comparable amounts of energy must be transmitted and stored in a comparable time (comparable means 1/3 of the amount of energy in relation to the "fuel" car - due to the high efficiency of the electric motor). So far, the accumulators with high specific power/weight ratio and the charging time are the relevant limitations. The more powerful the accumulators become, the more the charging infrastructure comes into focus, which must provide the required energy in a short time.


Interesting is the benchmark with the traditional system of refueling of gasoline (petrol or diesel). Here are (typically and roughly simplified) about 60 liters of fuel refueled (pumped) in about a minute - so one liter per second. One liter of fuel has about 10 kWh energy content (43,000 kJ per kilogram - converted into the common volume and power unit).

The efficiency of a piston engine in the car is typically about 33% and that of an electric machine higher than 95%. Accordingly, only about 1/3 of the energy needs to be transferred to achieve comparable ranges. In the example mentioned, this would be 20 x 10 kWh, hence 200 kWh.

That means charging 200 kW for one hour or, for a charging time of one minute, it takes for the same amount of energy:

60 x 200 kW; so 12,000 kW or 12,000,000 watts

This is an enormous flow of energy (energy per time) that has to be transmitted, and thus the accumulators, the power grid but also the charging device are confronted with enormous challenges. Even in the so-called "high-voltage range" with a transmission of, for example, 1,000 volts, it still requires very high currents to transmit this power.

Due to the common formula W = V x A, it quickly becomes clear that 12,000 amperes would have to flow in the given example.

For comparison: a household socket is protected up to a maximum of 16 amps, a one- to three-family house has a backup fuse from 80 to 150 amps - which are typically never used.

12,000 amps would mean huge cable cross-sections and contact areas. Even with a high-performance cooling, this could not be realistically implemented. So-called superconductors could be the solution if they were available at reasonable costs.


The example shows that the amount of energy for a standard range of 600 km for the electric car can not be charged as fast as a gasoline car. The charging time is also limited by the times in which a battery can still be charged and this amount of energy must be available from the power grid (for the low-voltage grid already a real burden!). For the charging time especially the charging cable and the plug still remain the bottleneck!

We have dedicated ourselves to this "bottleneck" and developed a power connector (plug and socket) with cable and cooling.


Problem solving

  • The paXos high-performance cable and plug are cooled by means of flow and return of a fluid.
  • The flow to the plug is made by a line, the return flow through the cavities of the twisted (stranded) single cables of the conductors.
  • The main conductors are deliberately distributed (and stranded) in many individual cables in order to achieve high elasticity of the overall cable.
  • The fluid can be passed on the plug (on request) to the socket and thus to the battery of the car to cool there.
  • The mechanical contact closure is no longer made by inserting a cylindrical pin in a cylindrical hole, but by a clamping loop around a contact ring.
  • The traction of this loop is made via a so-called ratchet grip.
  • The plug contains a servo valve in the form of a double ball valve.
  • At the end of the plug, in concentric pipes, the fluid can either be transferred to the socket or (if transfer to the car is not desired) returned.



  • With the large contact surfaces and the cooling, high currents (and thus a lot of energy per time) can be transmitted (> 3,000 kW).
  • The battery is cooled and conserved.
  • Inserting the plug into the socket and pulling it out happens nearly powerless because it is frictionless.
  • The actual contact closure happens via the ratchet grips by means of servo and thus forms a controlled contact, whereby additional security is achieved.
  • The plug has the contact surfaces for the substantial power transmission on its cylindrical outer side (several bands).
  • This part is protected by a plastic cylinder, which is turned back on a thread by means of servo as soon as the plug is inserted into the socket.
  • At the front of the cylinder only control currents are transmitted (CP and PP) and the fluid.