DC-DC converter mount, flowtest and batterybox support

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.

Draad tappen bodyplaatjes

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).

steunstang batterijenbak vooraan

Between the batterybox and the motor and at the top between the hood there is 14mm room. Fits exactly.

afstand motor

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.

Buehler 1.24.021Buehler pomp 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!

Buehler pomp connector

That allowed me to build a test setup. I noticed that sometimes the flow was a little low.

testopstelling Buhler pomp

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.

meten flow

Using this value I calibrated the flow sensors. The default value assumed for the pulse frequency in the Arduino code is 7,5.

arduino code flowsensor2

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.

DC DC op plek oude kachel

Now the phase of taking decisions and reducing the number of options has begun.

gat gezaagd voor DC DC controller

Using a wooden panel I created a mockup for the DC-DC converter mount.

steun DC DC met houten mal

rand haaks omgezet

I positioned the mount to allow enough clearance between the battery box and wiper motor (in the interior).

gehecht en passing controleren

This all fitted nicely so the mount could be welded.

steun DC DC zit erin

I need to finish it better, but the DC-DC converter has it’s place.

DC DC converter heeft een plek


Up next is the heater. I have a high voltage PTC heater.

Mahle Behr HV 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.

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