The last update of my ev-combi project was almost a month ago. Next to my job I was working on building a wood fired pizza oven (photo update, Dutch subtitles).
The front batterybox support which I worked on earlier is now ready. Welded in the body panels and cut the screw thread.
I welded the other part of the body plates to the support. In this way it can be easily removed and tightly secured (with an extra nut of course).
Between the batterybox and the motor and at the top between the hood there is 14mm room. Fits exactly.
My dummy box has a 12 mm bottom so I will gain some extra space.
Flowtest and calibrating flow sensors
Initially I wanted to use three Pierburg CWA 50 pumps for the cooling system. Even though by now I can dynamically control them for the controller circuit this pump is quite oversized. I started experimenting with a smaller pump, a Bühler 1.24.021.
This pump has a flow of 13 l/min at a pressure drop of 0,14 bar and only draws one amp.
Eltrex Motion (Bühler dealer for the Benelux) provided me with two free connectors despite the fact that they normally aren’t even for sale individually, thanks!
That allowed me to build a test setup. I noticed that sometimes the flow was a little low.
Therefore I created a test setup to calibrate the flow sensors. With some help from my family I measured that the pump had an output of 20 liters in 1:31 minute, so 13,2 liter/min indeed.
Using this value I calibrated the flow sensors. The default value assumed for the pulse frequency in the Arduino code is 7,5.
During the calibrations for my sensors the values turned out to be in the range of 7.05 and 7.55. Next step will be a flow test in the actual setup so together with the controller and DC-DC, but now at least I know my measurement is as accurate as it will get.
Mounted the DC-DC converter
Initially I thought in front of the controller would be a nice position to fit the DC-DC converter. Suddenly I found a much better place, where the heater used to be.
Now the phase of taking decisions and reducing the number of options has begun.
Using a wooden panel I created a mockup for the DC-DC converter mount.
I positioned the mount to allow enough clearance between the battery box and wiper motor (in the interior).
This all fitted nicely so the mount could be welded.
I need to finish it better, but the DC-DC converter has it’s place.
Heating
Up next is the heater. I have a high voltage PTC heater.
I no longer use the original heater and it’s fan was not optimal anyway (could blow soft and very soft). The car has quite a volume, so the question is, what kind of fan do I need.
After some research I found a Spal 008-A100-93D-3SP blower. It used 5 amps and delivers up to 260 m3/h. As a comparison a big computer fan will do 30 m3/h only.
