reef-pi :: An opensource reef tank controller based on Raspberry Pi.

[chipmunkofdoom2]

Because I was ignorant :-

Because I was ignorant :-( . I looked at the 4 channel version and amazon had written 10 amp current load. I intended to use it with return pump, light control , fan, air pump and the load seems fine (i might be completely wrong). The AC adapter socket I am using now has 5amp fuse as well. I am under the assumption that at high current load the fuse will trip first.
I recently learned about using SSD relays from scratch, i.e. instead of using a 4 channel board, use just relays, resistors, transistors , capacitors to roll you own, tht route certainly open up possibility of user much much better relays (https://www.sparkfun.com/products/13015) , but they will be more expensive , and I am not sure if I need this (need some help here), but the risk of frying my reef tank is low (i think).
I really dont know what EMR is, let me read up on that.
Currently my though process is to use the ssd relays and see if they fail for some reason, I can switch to the spare mechanical relay. Whats confusing is the webpage for those mention using optocouplers :-O .. Clearly I have lot to understand as things get deeper . My current loads are lot smaller (mostly pico, in some cases nano tanks ) we need folks to debate and challenge things, as long as its respectable and good for the corals . I appreciate all awesome feedbacks you are giving us @chipmunkofdoom2 , you make reef-pi better.

On a side note, there is this as well https://www.adafruit.com/product/2935 .

No trouble at all, I'm not an expert with this stuff by any means. I ask the questions because I don't know by EMR I meant electro mechanical relay, basically a traditional mechanical relay, the ones with the contacts inside and the magnetic coil that makes the contacts.

It's likely a solid state relay will suffice for almost all the things we would use reef-pi for, especially if the relays were rated for 10A like you mentioned. Personally, whether the relay was solid state or mechanical, I don't think I would try to use it at the uppermost limits of its rating. Just because the relay can handle 1,200W (120V @ 10A) doesn't mean the contacts on the board are necessarily rated for that much. You'd like to think if a manufacturer puts a 10A relay on a board, the board could handle it. But lots of these relay boards are no-name generics off Ebay. I don't know how much I'd trust them.

 

[denierlexiese]

@chipmunkofdoom2 and @Ranjib Should we target a 15 amp relay? My Eb8 for my neptune aqua controller 3 has a 15 amp trip button, so I would imagine that is what they are recommending. It looks like the energy bars, the 4 and 8 outlet for the new apex also use a 15amp trip buttons. Maybe 15 amp relay?

Amazon couldn't cancel the 8 channel solid state. [I'll manually send it back] I shouldn't use this relay because the chiller at 500 watts will be too much for the 8 channel solid state relay?

 

[chipmunkofdoom2]

Is the adafruit one, only has the ability to really control logically two states , on and off since, it connects via one gpio input?

So the left side both outlets are either both on or off, and similarly on the right side both on an off? So it would be more comparably to a two channel relay with a surge protector on each outlet?

Well so it looks like this thing basically operates off a SPDT relay. Here's a diagram for referece:



From what I can surmise, the outlets that are "normally on" are ON when you're not supplying power to the device through the green quick connect ports. The "normally off" outlets are off when you are NOT supplying power to the device. When you supply power to the device, the relay would activate. This would shut off the ON outlets, and turn on the OFF outlets. I actually did a DIY version of this to run my battery backup system. Basically, the relay pulls power from the wall when the power is on. If the power goes out, the relay closes again. This allows power to flow from a battery and AC/DC inverter to my critical life support equipment.

I don't think it's a surge protector really, just a way to use 5V/3V outputs to turn outlets on and off.

 

[chipmunkofdoom2]

@chipmunkofdoom2 and @Ranjib Should we target a 15 amp relay? My Eb8 for my neptune aqua controller 3 has a 15 amp trip button, so I would imagine that is what they are recommending. It looks like the energy bars, the 4 and 8 outlet for the new apex also use a 15amp trip buttons. Maybe 15 amp relay?

Amazon couldn't cancel the 8 channel solid state. [I'll manually send it back] I shouldn't use this relay because the chiller at 500 watts will be too much for the 8 channel solid state relay?

I suppose it depends what loads you want to run. To get a rough idea of total wattage, you basically multiply voltage by amperage (current). A two amp relay at 120V would be about 240W. If you want to power a 500W chiller, this would not be enough. 10A * 120V would be around 1,200W. A 10A would likely work for your chiller, but you could also go up to 15A to give yourself some breathing room.

Another thing to consider, inductive loads (like motors, such as AC pumps and the compressor in a chiller) have a large start-up current draw. Many AC/DC inverters are able to temporarily supply double their rated power for a few moments in order to supply inductive loads with the large power they need to get going. I would personally oversize your relay rating to help account for this large draw of power when the device starts up.

 

[Aaron Smith]

15 amp relays are not necessary. Energy bars like the apex have a 15 amp push button resettable fuse that controls the whole bar. Keep in mind that you are also limited to the circuit breaker that feeds the house outlet you are plugging into (generally 15 amp)

 

[denierlexiese]

I suspect my circuit breaker for the room is 15 amps. I will check the breaker box today. My estimates for my tank are
Lights: 320 watts Max - I'll have to double check. I think the black box 165 watt chinese leds actually run only at like 120 watts. Aaron can you confirm?
Chiller: 550 watts Max
Pumps [4 in total]: 150 watts

So I would think a 10 amp would run this with about 150 watts at least to spare.

 

[chipmunkofdoom2]

I suspect my circuit breaker for the room is 15 amps. I will check the breaker box today. My estimates for my tank are
Lights: 320 watts Max - I'll have to double check. I think the black box 165 watt chinese leds actually run only at like 120 watts. Aaron can you confirm?
Chiller: 550 watts Max
Pumps [4 in total]: 150 watts

So I would think a 10 amp would run this with about 150 watts at least to spare.

Remember the 10A rating is per channel. This relay, for example, has eight 10A relays. That means the board can switch 8 loads of up to 10A each. Essentially, each channel can be up to 1,200W (10A x 120V = 1,200W). Your chiller will be run on one relay, your lights will be on another, your pumps will be on another, etc. So, you don't necessarily have to add up all your equipment as each piece will be on its own dedicated relay. A relay board with 10A relays will be fine for the loads you listed.

You should keep the total load in mind though. As Aaron mentioned, your circuits are likely 15A/20A, so that's the max you'll be able to draw from the wall.

 

[denierlexiese]

Remember the 10A rating is per channel. This relay, for example, has eight 10A relays. That means the board can switch 8 loads of up to 10A each. Essentially, each channel can be up to 1,200W (10A x 120V = 1,200W). Your chiller will be run on one relay, your lights will be on another, your pumps will be on another, etc. So, you don't necessarily have to add up all your equipment as each piece will be on its own dedicated relay. A relay board with 10A relays will be fine for the loads you listed.

You should keep the total load in mind though. As Aaron mentioned, your circuits are likely 15A/20A, so that's the max you'll be able to draw from the wall.

The more I think about it the more I think it is probably 20 based on the room devices should be drawing around 2000+ watts, but I'll double check tonight. Thank you for your clarification.

 

[denierlexiese]

I scanned the solid state relays on amazon, and they all max out around 240 watts / 2amps it seems.

So do you all probably my best option is a mechanical relay like this one?
https://www.amazon.com/SainSmart-10...27424&sr=8-1&keywords=10A+sainsmart+8+channel

 

[chipmunkofdoom2]

I scanned the solid state relays on amazon, and they all max out around 240 watts / 2amps it seems.

So do you all probably my best option is a mechanical relay like this one?
https://www.amazon.com/SainSmart-10...27424&sr=8-1&keywords=10A+sainsmart+8+channel

Something along those lines would be my personal preference. I'll let everyone else chime in with their thoughts though.

 

[Aaron Smith]

I scanned the solid state relays on amazon, and they all max out around 240 watts / 2amps it seems.

So do you all probably my best option is a mechanical relay like this one?
https://www.amazon.com/SainSmart-10...27424&sr=8-1&keywords=10A+sainsmart+8+channel

Yup go with that one. They make cool clicking sounds too. [emoji41]

 

[Ranjib]

Something along those lines would be my personal preference. I'll let everyone else chime in with their thoughts though.

I'll echo the same, because of the 550w chiller

 

[Aaron Smith]

The simple fact is we do not switch the state of the relay often enough to justify the need for ssr. When building the PID controller for my pellet grill I used an ssr based on the fact that during a cook, my auger was switching states every 10 seconds or so. In reefing it is far less, even with heaters. At least it better be! [emoji16]

 

[Ranjib]

The simple fact is we do not switch the state of the relay often enough to justify the need for ssr. When building the PID controller for my pellet grill I used an ssr based on the fact that during a cook, my auger was switching states every 10 seconds or so. In reefing it is far less, even with heaters. At least it better be! [emoji16]

What about wave makers ? If someone wants to use the relays to switch on off power head.

 

[Ranjib]

Temperature controller will use pid controller as well (code is written for both, but they are not integrated now) ,it will switch on/off heater/ fan , I don't know to what frequency.

 

[Aaron Smith]

I am a fan of low volt wave makers. But if using 120v the amp draw is low enough to use the readily available low amp ssr.

Side note... Auto correct changes wavemaker to pacemaker on my iphone[emoji23]

 

[Aaron Smith]

I think PWM control of the wavakers is the ultimate way to go. I am a fan of the jebao pumps.

 

[Ranjib]

I think PWM control of the wavakers is the ultimate way to go. I am a fan of the jebao pumps.

Absolutely , I think all the way everything DC will be awesome, powering some of it via sun will be nice too

 

[Aaron Smith]

Absolutely , I think all the way everything DC will be awesome, powering some of it via sun will be nice too

I cringe every time I put another line voltage cord in my system being my background is in electrical.

 

[Aaron Smith]

The more I think about it the more I think it is probably 20 based on the room devices should be drawing around 2000+ watts, but I'll double check tonight. Thank you for your clarification.

The funny thing is back in my apprentice days, we were bored one day and decided to lock up a big hole hog drill with an amp meter clamped onto the circuit. We easily pulled 35 amps on a 20 amp circuit before the breaker tripped. Then go home to my wife who is able to trip any circuit breaker in the house with a hair dryer. I don't care what anyone says, electricity is magic, which makes me freaking Gandalf!