Electric brake booster

While I am waiting for the really fun stuff to arrive, the motor, controller, adapter and batteries, I put together an electric brake booster for the car.
In a car with a diesel or gas engine, the engine produces vacuum which is used to boost the brake pressure so that you don't have to press the brake pedal so hard.
When I remove the enging there will be no more vacuum so I have replace that with something else.
So, I built a brake booster from a vacuum pump and vacuum sensor from an Audi A4, an old Sigg bottle that I used to have kerosene in for an outdoor stove, a contactor and the Arduino micro processor.
I use the Sigg bottle because it is red ;) and because it is aluminum. Since the car is made mostly from aluminum I want as much of the parts to be so as well.
The Arduino runs a very simple software the reads the pressure and turns the pump on and off between 600 and 800 mbar of vacuum.
The contactor, which is actually the security contactor that will be used to brake the high current circuit, will be replaced with  simpler 12V automotive relay.

Have a look at the video:

Testing the vacuum pump and sensor

Today I tested the my vacuum pump and vacuum sensor. Both pump and sensor are from an Audi A4 and the pump increases the vacuum from the petrol engine when the throttle is fully open and the vacuum is low.

The vacuum pump...

... and the sensor

I connected the pump to the sensor with a vacuum gauge in between. The sensor is fed with a 5V signal and produces a voltage between 0.3 and 4V depending on the vacuum. I used my index finger to block the sensor and produce a varying vacuum in the circuit.

The (chaotic) setup of the vacuum test

It turns out the vacuum pump delivers a max vacuum of 900 mbar and I plan to use it between 600 and 800 mbar with a simple on/off controller.

At 600 mbar the sensor produces a 1.5V signal and at 800 mbar it produces about 0.5V.

So, tomorrow I will build a simple on/off controller with my Arduino computer

Running the AC/DC on DC

I made a simple DC power source today by connecting a 500V rectifier bridge and a 1mF, 400DVC electrolytic capacitor to mains 230VAC. The result is 327VDC which I fed into the DC/DC (which is an AC/DC) converter.

And the DC/DC nicely output 13.9 VDC so it seems to work!
Didn't try it with any load though.

CAN Bus Analysis started

I managed to tap into the Drive Train CAN Bus today. The Audi has three CAN Busses. One for the motor, transmission, power steering and brakes basicly, the second for the air conditioning, windows and door and the third for the radio, navigation systems and so on. I need to understand the drive train bus in order to emulate an engine so that the ECU (Engine Control Unit) stays happy and, most important, so that the power steering works. The power steering turns itself off when there are no CAN Bus messages from the engine with the RPM.
I have been trying several times to access the CAN Bus through the diagnostics connector but it has been dead. Today I tried one of the contacts in the foot weell in the double floor on the driver side.
Success! It worked after I had also grounded the Arduino to the car body.

The driver side foot well with the Arduino with CAN Shield

I managed to connect my home-built Arduino CAN Bus sniffer and get a lot of data out of it.
Now I only need to understand what all of it means ;)

Actually I managed to decode one CAN Message, Id 0x280 which is RPM (hooray= and I almost managed to work out which of the eight data fields are actually used. Well, I'll get back to that.

The Tyco

The Tyco Kilovac 500A, 500VDC contactor. Heavy stuff!

More stuff arriving

Today I got the Meanwell SP-750-12 AC/DC converter that will act as a DC/DC and power all the 12V stuff in the car. I tested it on 220 VAC and it produced a nice 13.9 VDC unloaded. According to specs it will do 13.5V and 750W.
It would be fun to test it with DC input, but I haven't got a DC powersource with enough voltage yet. It needs at least 127 VDC.

Finally something happens!

I haven't been doing much on the project for quite a while, I must admit. I have been driving around in my little A2 which is a quite nice car even with a gas engine in it ;)

But now things are starting to move again!

I have shopped around for parts and they are slowly arriving at my garage.
68 CALB100FI batteries have been ordered from ev-power.eu. The are due to get here in the end of June.
A Brusa NLG-513 charger has arrived from Brusa in Switzerland. The Brusa is the best charger around, I think, since you can configure it pretty much anyway you like. Brusa actually had a sale on them so I got it for half price! :)

The Brusa charger with cables 

After some discussions with Joost at Rebbl in the Netherlands I decided to order a Meanwell SP-750 AC/DC converter from Elfa to use as a DC/DC converter. Sounds nuts, but it turns out the Meanwell can take AC as well as DC current as input. Up to 370VDC input and it produces a nice 13.5VDC which will charge the little 12V battery a bit. I am taking a chance that it's power, 750W will be enough. The DC converter is CE marked and has nice EMC certificates.

A Kilovac 500A, 500V contactor is on its way from Farnell in the UK via its Swedish reseller Microkit.
Today a used transmission from a Audi A2 1.4TDI arrived. as did a clutch from the same car and a flywheel from a VW Polo. I have to change the transmission too, remember? Just like I changed the brakes just because of stupid Swedish regulation. Nevertheless It is good to have it here and being able to measure it without ripping the car apart.

Flywheel and clutch

The flywheel is from a Polo with the same engine as the A2 (1.4 TDI with motor code AMF) so I hope it will fit the transmission. Look at the picture below, it is tight!

I am thinking of maybe buying a VW New Bettle motor adapter from Rebbl and I have sent them some measurements of the transmission and flywheel to check if it will fit.
More stuff I have to decide upon now are AH meter to measure battery charge, current shunt, volt meter, a 500A fuse, shielded battery cable, battery connectors for connecting the CALB cells to eachother and a lot more...
I have pretty much decided to go for the Kostov K9HV motor and the Evnetics Soliton Jr controller, but they are not ordered yet.