First Use of our Wallbox

Wednes­day, Sep­tem­ber 28, 2022, 7 a.m. in the park­ing garage Obere Königsstraße 31 (Gale­ria Kaufhof) in Kas­sel. Solar­na­tive work­ing stu­dent Hen­drik and col­league Flo­ri­an woke up extra ear­ly to pick up the rental car for a very spe­cial day: the Renault Zoe from car shar­ing provider scouter is our guinea pig for the first test charge with the in-house devel­oped wall­box, part of our Smart Ener­gy Home Sys­tem. It is a very spe­cial project for Hen­drik: In March 2022, he decid­ed to devel­op a wall­box, the “EV Stick”, under the guid­ance of CTO Henk Old­enkamp for his master’s the­sis of Elec­tron­ics & Automa­tion at Solar­na­tive. After 5 months of con­cen­trat­ed devel­op­ment work and numer­ous tests, the cir­cuit design and lay­out were set – now it was time to build the first func­tion­al ver­sion of the device in the lab­o­ra­to­ry. To this day it was uncer­tain whether the step from the­o­ry to prac­tice would suc­ceed imme­di­ate­ly and whether the wall­box would suc­cess­ful­ly charge an elec­tric vehi­cle. Con­se­quent­ly, work­ing stu­dent Hen­drik and all Solar­na­tive col­leagues in Lohfelden are super excit­ed about this first test charge.

After arriv­ing at the park­ing lot of our Lohfelden office with the rent­ed Renault Zoe, prepa­ra­tions for the test start imme­di­ate­ly. With a few screws, the EV Stick is attached to a wood­en post that the team has placed at the edge of the park­ing lot for this pur­pose. Unfor­tu­nate­ly, we’re expect­ing rain and the team has to impro­vise a lit­tle: Two large umbrel­las are attached to the post and table leg with a lot of duct tape. They are intend­ed to pro­tect both the elec­tron­ics of the lab­o­ra­to­ry wall­box and the lap­top that is con­nect­ed to mea­sure var­i­ous data from the rain.

Around 2:20 p.m. all prepa­ra­tions have been made. The entire team at our Lohfelden office has gath­ered around the test set­up. The moment of truth has arrived: will the vehi­cle charge?

Filmed by col­league Flo­ri­an, Hen­drik takes the con­nec­tion cable from the wall­box hold­er and plugs it into the charg­ing sock­et of the Renault Zoe. The vehicle’s indi­ca­tor flash­es orange for a few sec­onds … and then turns blue: the vehi­cle is charg­ing! “Wow! Wow, wow, wow!” calls col­league Man­jesh from the cock­pit of the vehi­cle and claps his hands. The test charge is a suc­cess! A proud moment for work­ing stu­dent Hen­drik: The proof of the suc­cess of his work has been pro­vid­ed – just in time for the sub­mis­sion of his master’s the­sis next weekend.

The most impor­tant ques­tion has now been answered. But in addi­tion to some mea­sure­ment data that the team wants to col­lect on this day, there is anoth­er ques­tion to ask: will the vehi­cle charge at full speed with 22 kW when the bat­tery is suf­fi­cient­ly dis­charged? So: hit the road and drain the bat­tery a bit. Hen­drik and Flo­ri­an race down the auto­bahn for about an hour lis­ten­ing to rock clas­sics on Radio Bob to dis­charge the bat­tery to below 70%. Because if the charge lev­el is too high, the charg­ing speed auto­mat­i­cal­ly restrains to pro­tect the battery.

After return­ing, the solar natives recon­nect the vehi­cle to the wall­box. And anoth­er rea­son to cel­e­brate! The mea­sure­ment shows: the cur­rent flows with the tar­get strength of 32 A, which cor­re­sponds to an out­put of 22 kW, from the wall­box into the Renault Zoe.

At the end of this spe­cial Wednes­day, Solar­na­tive is in high spir­its. There are still a few steps to be tak­en before our EV Stick is ready for the mar­ket. But these are large­ly “hygiene fac­tors”, such as installing an earth leak­age cir­cuit break­er and a com­mu­ni­ca­tion chip, and final­iz­ing the hous­ing. The test showed, the func­tion­al­i­ty of our Plug & Play Wall­box is there.