Call for collaboration

[Jpadie]

@mooseau
thanks for asking - my first set of bespoke boards arrive via FedEx later on this week. The design mostly worked on my jerry-rigged boards at the end of the summer but not perfectly - i think loose connections were to blame. The bespoke board should resolve that.

I have built in ports for pressure sensors, but don't intend to use them myself and all my pressure transducers are deployed elsewhere. the current board will handle dosing and measurement. it has PWM outputs for controlling a VFD and PWM outputs and current sensing for 'controlling' a chlorine generator. I've not yet built a board for the actual control of a chlorine generator. I do have the rudiments of a design and I know it will need a micro-controller to do the current measurement and PWM output (hence the other board having this functionality). But on the whole I don't want the two boards to be on the same copper as the current/power handling requirements for the chlorine generator board are very significantly higher and may need a higher density copper substrate (which adds significantly to the cost of fabrication - US5 vs US47 for 10 boards. the cost differential slightly diminishes after that.

Happy to share the design if people would like to critique. there should be another couple of chances for iterative improvement before my pool needs to be opened. And before that I have to break out mountains of concrete to re-plumb the skimmers.

 

[Jpadie]

I should add that my 'homemade' salt cell works superbly. I got the plates made and shipped in China (happy to share and recommend the supplier). Half an hour with an angle grinder and a drill and some time with a 3d printer and the cell is deployed in the system neatly. Nine panels of 200 * 40. Ruthenium-Iridium coated. 180USD. From memory I was getting 13A current draw at 9v.

For my pool (26.5 kgallons) my estimate is that it should produce 34g of chlorine gas per hour and I would need 9hrs or so per day to go from zero to 3ppm. My maths is probably wrong but that equates to just under 5 euro per month of running costs for the salt cell. and of course I should not fully deplete each day. Low bather load in my pool so I'd estimate perhaps only a realistic 1.5ppm uplift each day. which equates to a running time of 2h50m and a spend of 1.50eur per day.

 

[Dirk]

Home made salt cell. Amazing!

 

[Jpadie]

Home made salt cell. Amazing!

 

[Dirk]

Do they come is a choice of colors!!??

So cool. Looking forward to seeing a pic of it in action, and hearing about the real-world results.

 

[Jpadie]

Do they come is a choice of colors!!??

I do like a bit of orange!

I'm interested to see how the plastic has survived the winter, likewise.

 

[chlorinatorpro]

<I got the plates made and shipped in China (happy to share and recommend the supplier). Half an hour with an angle grinder and a drill and some time with a 3d printer and the cell is deployed in the system neatly. Nine panels of 200 * 40. Ruthenium-Iridium coated. 180USD. From memory I was getting 13A current draw at 9v >

I would like to know who you sourced plates from in China. Do you recall what they promised as far as the coating thickness? 5000 hrs, 7000 hr, 10K, 15K? These appear to longer, narrower plates than we would use in Hayward cell in the USA. Although the total surface area is similar to what would be found in a T-15 cell.

Thank you.

 

[Jpadie]

The manufacturer was Baoji Highstar. Email address: [email protected]

The Ru-Ir coating was 8-10um. This was 25% thicker than other suppliers I spoke with. NB the price includes freight.

I don't recall discussing operating time with them. But others with thinner coatings quoted in excess of 6000hrs

On size: the manufacturer milled them to my specification. You can get what you want. I had not taken my existing cell to bits so was guessing at my spec at the time. Hence the need for an angle grinder after!

 

[Jpadie]

Just to follow up on this, the salt cell has been happily chuntering along with my old chlorinator as the controller (I've not had time to kill that but I am building the pool management boards this weekend, work permitting). It's settling at 13Amps which is 30% more than I anticipated as I had thought the controller was current-limiting at 10Amps. My calcs show that 13Amps produces 34g of Cl gas per hour. For me that means 1ppm an hour. Pool salinity is around 4.2ppm using the strips.

all good from my perspective!

 

[Jpadie]

for those interested, here are the designs of my mk 102.1 pool controller. it supports

2 * 13amp relays (intended for toggling lights and a pool auto-filler but could be used for any load, including a pump or SWG or robot booster pump)
3 * mosfet driven loads (intended for peristaltic pumps to dose Cl, acid and alkali)
2 * pressure sensor (low voltage types)
1 * ORP sensor
1 * pH sensor
1 * digital temperature sensor
1 * float switch
common to pool ground (to help avoid noise)
inverter driven pump control (modbus-RTU or analog potentiometer emulation plus digital run/stop)
water level detection
auto-fill
it also has all the circuitry to _control_ a SWG. The SWG system itself is designed on to another board as the power requirements are significantly different to the requirements of the control board.
WiFi

control may well be available just through a customised template and driver in Tasmota. But equally I might write my own interface. this could sit above tasmota or replace it. Either way there will be an alexa interface for simple stuff like changing the pump speed and getting information from the sensors.

these should arrive in ten days or so. Hopefully I can install one shortly after. Currently it's due just to go into an ABS box and the sensor connections will get sheathed in shrinkwrap and passed through cable glands. Not pretty but serviceable.

If anyone has recommendations for improvements I'm all ears.