Need some help on a controller. Burnt out two already, I think.

[gregkeller]

So not a specific electric brewing question, but maybe those of you on here with some experience can give me some ideas.

I built a peltier cooled conical about 3 months ago based off sort of reverse engineering a morebeer ultimate conical. I've got 4 peltier chips (tec-12715) and a computer heat sink on each of them. I originally bought an inkbird temperature controller which seems like it should have been able to handle the load. The entire thing is powered by an 800 watt computer psu. The controller says it's capable of handling 1100 watts, so I thought I was good to go. After about 3 batches of it working absolutely perfect, I went down to the basement to check on a lager and it was way colder than I had set it. Basically the temp controller wasn't switching it off, even though the display said it was "heating" which means it should cut power to the cooling plug and sent it to the heating plug. Figured it was a one off thing and I replaced it immediately with an STC-100 temp controller that I had built a while ago and wasn't using.

That brings me to today. I had the exact same thing happen to my STC-100. Went to check on an IPA that had been finishing up at 70 degrees and was going to crash cool it and it was already at 9 degrees C. Same exact failure where the STC says it is "heating" but the cooling plug that the PSU is plugged into is still getting power.

I need a way to fix this. The morebeer conical has separate power supplies for each peltier unit, but they are all plugged into a single temp controller. The morebeer unit uses a Ranco which runs about 180 for a heating and cooling unit.

Am I burning out a relay? that seems like the obvious reason. If that's the case, can I build a temp controller with an STC that switches a more robust relay that won't fail on me? I was thinking PID, but this thing, I think, would be better served with a simple on/off type of thing. I wouldn't be opposed to a raspberry pi/arduino type of thing IF it could be done for less money than a Ranco dual stage temp controller. I love the idea of being able to program in a fermentation profile, but I am more looking for something that is bulletproof and isn't going to s**t the bed every few batches.

Sorry for the longwinded questions. I'd love to hear any ideas.

 

[doug293cz]

I think your relay contact points in the controller are getting welded shut. I'm not a power supply expert, but I believe switching power supplies present an non-resistive load, and that they can have very high in-rush currents at turn on, and create kickback voltage spikes at turn off. I think you would be better off driving the power supply from an SSR, which can be controlled by a PID, RaspPi, arduino, etc. I'd go with a 40A/240V rating just to be safe, and stay away from Fotek SSR's (many are poorly made counterfeits.) It could all be done with a MyPin PID, a power switch and an SSR.

Brew on

 

[augiedoggy]

So not a specific electric brewing question, but maybe those of you on here with some experience can give me some ideas.

I built a peltier cooled conical about 3 months ago based off sort of reverse engineering a morebeer ultimate conical. I've got 4 peltier chips (tec-12715) and a computer heat sink on each of them. I originally bought an inkbird temperature controller which seems like it should have been able to handle the load. The entire thing is powered by an 800 watt computer psu. The controller says it's capable of handling 1100 watts, so I thought I was good to go. After about 3 batches of it working absolutely perfect, I went down to the basement to check on a lager and it was way colder than I had set it. Basically the temp controller wasn't switching it off, even though the display said it was "heating" which means it should cut power to the cooling plug and sent it to the heating plug. Figured it was a one off thing and I replaced it immediately with an STC-100 temp controller that I had built a while ago and wasn't using.

That brings me to today. I had the exact same thing happen to my STC-100. Went to check on an IPA that had been finishing up at 70 degrees and was going to crash cool it and it was already at 9 degrees C. Same exact failure where the STC says it is "heating" but the cooling plug that the PSU is plugged into is still getting power.

I need a way to fix this. The morebeer conical has separate power supplies for each peltier unit, but they are all plugged into a single temp controller. The morebeer unit uses a Ranco which runs about 180 for a heating and cooling unit.

Am I burning out a relay? that seems like the obvious reason. If that's the case, can I build a temp controller with an STC that switches a more robust relay that won't fail on me? I was thinking PID, but this thing, I think, would be better served with a simple on/off type of thing. I wouldn't be opposed to a raspberry pi/arduino type of thing IF it could be done for less money than a Ranco dual stage temp controller. I love the idea of being able to program in a fermentation profile, but I am more looking for something that is bulletproof and isn't going to s**t the bed every few batches.

Sorry for the longwinded questions. I'd love to hear any ideas.

stc has a 10a relay. Not sure if the 4 chips are drawing more than the 12v channel of ps is rated for (800w is the total all the different power supplies in the computer ps if im not mistaken including the negative 12 ,5 and 3.3v supplies the single 12v output is usually much less and your 4 chips draw like 650w alone and 62amps which is way more than the 10a relay is meant for..) I agree using an ssr or even an external heavy duty mechanical relay should work.. The stc1000 relays are known to fail over time just running a 7 amp fridge with a higher compressor startup load higher

 

[BrunDog]

The 15 at the end of the part number is the current of the chip, so they are 15A in your case. That’s 180W at 12V nominal. 4 makes 720W. Assume 85% conversion in the power supply to get 850W. That’s only a few amps at 120 VAC, so the relay in the STC has the chops.

 

[golfindia]

+1 Switching power supplies have a huge inrush current. I would switch them with something other than the internal relay. Or leave the PS on and switch the output. I have a 55amp power converter/charger for a solar bank that will trip surge protector and GFCI outlets with a decent spark at plug in.