Heater fan control, electronics and checking out the Hesla

Since the electric heater with recirculation is now ready, I started working on the controls. The basis is a high voltage PTC element which generates more heat to the degree you cool it down. As a result most heat is being generated with the fan/blower at full speed.  At Rick Donkers auto electrics I bought two four position switchs and connected it to the original levers.

vier standen draaischakelaar

vier standen trekschakelaar

The rotating switch did not survive the attempt. The sliding switch works fine.

However the bend cable is quite fragile and a continuous control would be better. Thanks to the suggestion of Erik I looked into PWM control like I do with the Pierburg pumps. Created a test setup for controlling the speed of a DC motor.

Worked very nice so I hooked up the blower instead of the small motor.

That made quite some noise. Erik proposed the solution by using another PWM freqency. Also added a mosfet to be able to handle bigger currents. And implemented the orginal fan switch. If you just slide the temp lever you get hot(ter) air. If you pull the original fan switch that gets overruled and you have two fan speeds.

Later I can configure how fast I want the blower to be at those two speeds.

EV Econometer

I want to keep the original speedo but the fuel indicator and to less extend the temp meter are not that relevant anymore. Ingmar suggested to add a econometer. While I was into controls anyway I created a protoype. Hans gave me an old B20 temp indicator with the red scale. I transplanted that onto a fuel indicator and it works!

In case of high enery consumption for example when accelerating fast I can turn the needle towards red, center it during normal use and to the left when regenerating.

Documenting prototypes in schematics

I learned a lof from Erik (thanks!) about gate drivers, mosfets, input capacitance, creating schematics. It’s now all written down in TinyCAD.

prototype omzetten in schema

And not only controlling the blower, remote controlled stationary heater, CAN-BUS module and temperature sensors.

Arduino PCB TinyCAD IMG 9205

Hesla at Cleantech Tomorrow

Earlier I heard about the Hesla, a Tesla with a hydrogen range externder in the below video (in Dutch) by Vincent Everts.

That did trigger some questions from my end.

00:45 & 1:35 Converter fuel cel voltage = 350V, efficiency?
01:44 Capacity fuelcel = 75V and 256 Amps
01:57 This is a 30 kW module
03:25 Efficiency fuelcell 60%

But if the fuelcell is 75V and a max amperage of 256 A, then the power is 19,2 kW, right? If you run it for one hour it is 20 kWh?not 30 kWh? Assuming the DC/DC converter for creating 350V is highly efficient. The Hesla was at the Cleantech Tomorrow event in Teuge and I was able to check it out. Some of my questions were answered, but not all.

Hesla Tesla op waterstof IMG 9159

By the was, there was also an electric plane at the event.

Elektrisch vliegtuig

Hesla update from Vincent

A new video has been added with some more information.

The fuelcell is 60V and 230 Amps which is 13 kWh and is about 50 km/h for a Tesla. A kilo of hydrogen delivers about 25 kWh at an efficiency of about 70% so gross about 33 kWh. A full tank contains 4,4 kg hydrogen at 700 bar. This allows them to recharge a 100 kWh batterypack one time. One kilo of hydrogen costs about 10 euro and later this year that will be 7,50 euro. As a result one kWh is 0,40 eurocents. Depending on where you normally charge this is about 2 to 4 times as expensive as charging electricity directly. The hydrogen setup costs about 42.000 euro. It’s a range extender that is only interesting if you want more range that 400 km (on average, since the range of a Tesla is between 355 en 695 km). At a speed more that 50 km/h the fuelcell cannot topup the Tesla battery realtime. As soon as the SOC is running low, you need to stop to allow the fuelcell to charge the car. Without a plug! Interesting developments to follow since also this will become more compact, lightweight and cheaper.
I do have some remaining questions:
  1. How do they interact with the Tesla BMS?
  2. What about it’s registration? Currently it still is listed as a car driving on electricity. Does it still needs to be approved and will then hydrogen be added as a fuel? Similar to cars driving on pertol and LPG.

In the video it is mentioned that they do not touch the Tesla systems and that the Tesla warrenty remains in place. But how then do they get the energy into the Tesla batterypack? Perhaps I should get in touch with Holthausen to find out, very interesting.

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OldVolvo is a classic Volvo hobby blog by Lars Rengersen.

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