DC System / Vehicle Automation - Need help from the brain trust....

[Versafel Systems]

Hello all,

So I have automated my work van. Yes, you read it correctly. Yes I am a nerd. 

 

I scrounged up a bunch of out of warranty equipment, a couple of KMTronic relay packs and some Shelly's pieces. And I fully automated my work van. Its not a normal Sprinter work van, as it has many similar system to an RV. Including a huge lithium battery system. The van is used both for work during the week, and for play on the weekends. As well as out of town jobs in remote areas.

I've been thinking about this idea for over a year at least. I was like "My house is really smart and my vehicle is really dumb. This isn't right, I can do better"

I was always leaving some sort of system on overnight or over the weekend by accident. And because my charging system was limited to 50amps off the alternator,  I struggled to charge the batteries back up with just daily driving for work.

So recently I re-built my power system and added the automation. Now the system can charge at 80 amps. And C4 really improved my ability to charge at higher rates by designing "charge profiles" that C4 handles via some high current relays and some variables, all the while being fed voltage information from a Shelly UNI. Its been working awesome. And being able to remote into the van and turns things on and off, like the furnace or the door locks is game changing.

 

Here is where I am looking for some help:

There is a MaxAir fan with a brushed DC motor on the roof to exhaust air out or into the van. Prior to the rebuild it was controlled via good old fashioned switch for power, and a PWM motor controller with a manual variable potentiometer for speed control. It worked great.

Now C4 has control of the power, and the reverse polarity relays to change direction, that's easy. Where I am stuck is adding some sort of variable speed control from in C4.

I have ran down these rabbit holes trying to find a solution:

 - one of my shelly RGBW2 has a channel left over. I ran it through an amplifier then to the motor - it worked! But because the Shelly RGBW PWM frequency is 1khz, the motor had the loudest PWM whining noise. No bueno! (Bushed motors are usually controlled at 15khz and higher to avoid this sound)

- again with the leftover shelly channel - I thought I could maybe use the PWM output to feed another PWM motor controller that had PWM input - but the shelly PWM output is negative voltage - all the PWM motor controllers with PWM input want a positive voltage signal. And most want only maximum 5vdc PWM signal.

- maybe a 0-10v dimmer? DC motor controllers with 0-10v input do exist, albeit more $$$ than I like. And I would have to turn my 120vac inverter on to run the 0-10v dimmer. Its not very elegant and the programming would be clunky. But its a solution.

- I could use a couple of relays and some resistors to mimic the potentiometer. Relay 1 NC - low speed, Relay 1 NO - medium speed, Relay 1 NO + Relay 2 NO - maximum speed. it works, but is sooo lame with only 3 speeds. At least 10% increments would be cooler.

 

So I am stuck at this point. Anybody got some "gotcha" I haven't thought of yet? I’m certain there is a Raspberry Pi or Ardiuno solution but I haven't taught this old dog to code yet. This group helped me out with a customer's DC power system by suggesting the Shelly devices recently. So I am hoping you are all smarter than me one more time.

 

I have attached some Detective Suite PDF's for your entertainment.........

 

Cheers!

 

Jean Claude Van Diesel Report 2.pdf Jean Claude Van Diesel Report 1.pdf