HeaterMeter Buddy- SSR companion for electric smokers

[Nauglanch - Mike]

Presenting my latest project and first for the HeaterMeter. The HeaterMeter Buddy. It is an SSR "Buddy" for electric smokers

As with many HeaterMeter initiates - the HeaterMeter is a great can't-live-without item (like my first microwave 30 years ago). The issue is I have an electric smoker (a gravity feed pellet in the works) and it's just begging to use the HeaterMeter SSR PID control capabilities.

So I introduce the "HeaterMeter Buddy"

Basically it's a 25A SSR in a case with ethernet jack input, power in, and SSR controlled power out.

But I added a few bells and whistles. Power and Output Power lights. Fuse (Always have a fuse!), Aux SSR Inputs (just for flexibility around the shop), and a 2nd power out, always on, for the Heatermeter 12V power supply, and output power control switch.

Yes, I thought about back powering the HeaterMeter from the HeaterMeter Buddy. But I just couldn't fit in a 5V power supply and didn't want a larger case.

For connections you'll note I use cords. Why? Because I find chassis connectors take up a lot of room. I find they're also not very secure for heavy cable wrangling. Yes you can get uber ones but that's money and even larger product. With cords you get the same effect and cord chassis fittings are inexpensive.

I buy TrippLite 14G auxillary extension cords. If I need a short plug and a short socket I just buy a 3' (their shortest) and cut it in half. And for many of my shop accessories that get moved about I just use 6" outside the case (leaving 1' inside for wiring so can split a 3' cord). In this case my Smoker is in the same place so I used a 15' full length cord so I dont have to always add in an extension cord. The Smoker plug is shorter s it just needs to get to the smoker (so mine 3') , and the HeaterMeter power wart needs to be close so just 6" or a foot long. This is my favorite way now of connecting power to my projects.

My larger PID controllers with metal cases use the case as the heat sink. That works OK for the most part. But this case is pretty tiny - and the SSR will dissapate 15W at 1000W load and 23W at 1500 watt load. Yes at 100% - but maybe that's your large electric smoker in winter. So a heat sink for this small case. Generally with a reasonable heat sink one doesn't need a fan. And it's OK if the box runs "pretty darn warm"

For the heat sink, well, how to size one? This one seemed right. I have smaller ones on other SSR controllers but this is a small case. This just seemed right. It's 100mm x 50mm x 20mm or so. It was a tad wide hanging over the sides and being sharp. So I cut 1/4" off of it.

A very usefull option to me is the switch. It's 3 position with center off. This lets me have everything powered up - but some manual control. Like heat off while I adjust the pan and such. Or heat at 100% to pre-eat. Or for rutime it selects the SSR output.

For the labels I use a Ptouch label maker with black on clear and white on clear (in this case) labels, I cut them to just around the letters and carefully apply (and re-apply until right! use toothpicks, xacto knife edges, patience!). Rub them in good and carefully. Apply a coat or two of clear gloss or semi-gloss to lock them and their edges in place.

Before you build - lay everying out. Put your parts on the front and back, with double sticky if necessary. See how the layout seems and works. Make sure you've got top and bottom and side clearance. And room for wires.

Similarly take those end pieces and put them up to the case and see where the SSR goes. In this case I left room in the front for the fuse and switch wires (as the back power wires were bendable). I put the SSR to the side to leave routing room for the high power wires for straighter runs to the switch and the fuse.

Only then mark and drill for the SSR. Use blue tape and consider using a square to square up your marks and holes. Use a center punch or spring punch to make a dimple to start your drill.

Now you need to mount your heat sink. I drew a centerline on the bottom with fine Sharpy. Put that on the top, flip, and line up all the way around. Mark your holes with sharpy or pen. Double check, center punch and drill.

Note I have 3 screws. Two for the SSR are required. For the heat sink I wanted both ends secured the same. So I added the third. Thats why two look close. The "middle ish" SSR mounting screw and the final end one.

You'll now have to remove fin material on the other side. This is a PITA but I used my milling machine. A drill press with the sink in a vise will work (use a router bit straight cutter as an option).

Now test fit the heat sink, top, and SSR. Make sure you're happy. I advise using a dremel wire wheel or such to remove paint in the SSR and heat sink area.

Now you can put that assembly together - but I recommend just attaching the SSR loosely. This is so it's in place for fitting wires - but it sits flat on the work bench. Just easier to work with.

When finally affixing the heat sink and SSR ensure you use a properly thin layer of heat sink compound. Since my top was finely ridged I ensured the valleys were filled. Now clean it all up! It gets everywhere!

One issue of the HeaterMeter is it's light weight in combination with the heavy, tangly, pull of all those cables. Cables are a PITA! And I wanted it (mostly) to be with the HeaterMeter Buddy.

So I got a stack (well 8 out of a stack) of disc 1mm rare earth magnets (10mm x 1mm or so). Remove the 3M or sticky layer if they have them. Fingers, rub, Goo Gone. But you want fresh metal for the E6000 glue. The sometimes pre-applied stickum doesn't hold well on non smooth surfaces like a HeaterMeter and maybe not your case.

Glue 4 to the bottom corners of the HeaterMeter.

Watch it as they'll fly off and stick to each other. So you may want to do oppposite corners at a time until you get the hang of it. I found it easier if they near ones were opposite polarity. Otherwise one pushed the other apart/off. It just seemed more stable that way. Play around before applying glue!

I used (and like for many things - but every glue has a purpose - none are universal) E6000 a slightly runny clear rubber. Awesome stuff. Get you some and get hooked!

Once the bottom magnets are well secured - and for E6000 just wait morning to evening or overnight - otherwise you still risk pulling them off until fully cured.

Now take the other 4, adhesive removed, and gently let them click onto their mates. This "stuck together" is your "precision alignment jig" for gluing.

Figure out where you want the HeaterMeter on The Buddy (or wherever you want to do this that needs magnets applied). Do you need a spacer (things will move some on you). I used a pencil between the heat sink and the back of the HeaterMeter. Get good eyeball on this and get everything in place or nearby.

Apply a small (pea sized) dab of E6000 to each magnet bottom . Watch the E6000 is it can be a tad stringy. Ignore strings or any minor issues for now.

Carefully position, apply, and with gentle pressure push it down and on and adust against your stop (my pencil). Don't push too hard as you dont want glue starvation.

If you didn't use too much glue then you'll have some squeeze out that will make a nice fillet around your magnet. If you've made a huge mess -then wipe it up - otherwise leave it and you can rub off/out minor strings and such.

Leave overnight!!! Dont be tempted to test it !!!

Now you have a snap on / snap off HeaterMeter - to anything magnetic - and you have a precision mounting on your HeaterMeter Buddy. Enjoy!

For materials - nothing special

• Case is 100mm x 150mm x 25 or 30mm. ePray China. This one came hard anodized black (unfortunately somewhat of a heat soak for a heat generating device! Paint!
• 120V LED indicators from Auberins
• Fuse Holder from any electronics supply, ePray, Amazon, Jameco, etc
• SPDT Center off Switch from any electronics supply or home center
• Ethernet Jack from monoprice or for just a single from Lowes or home center
• Banana jacks from ePray (surplus Palomar in this case).
• Power cord fittings from Auberins
• Power cords from Amazon
• SSR from Auberins or your favorite supplier. I recomend MGR over "generic Chinese" even though it's also a Chinese product - it doesn't seem to be cloned, has a cover, and has an indicator light. Other BBQers seem to have acceptable results from generics. You can get MGR from Auberins (seems to be their house brand) or ePray. Check prices. I recomend a 40 or 50A for durability margin due to heat, heat sinks, starting loads, shorts to survive until fuse blows. Read below about my blown SSR and why I now recommend a 40 or 50A.

Now I must split this post!

 

[Nauglanch - Mike]

Let's Build it

First I added some paint. Not strictly necessary but the box was hard anodized black. Which means in the sun it's going to be it's own heat source. We want to dissapate heat from the SSR in the box. We don't want to add to it.

I thought of smoke and fire and chose red and yellow. My friend called these "Circus Colors" until I reminded him this was for a smoker. Flames? I could use the vinyl cutter but wasn't sure the fine ridges in the case would seal and not bleed.

I always put a coat or two of clear but not strictly necessary. The back is black because I finished it before deciding to paint. No biggie!

Here's the front panel front. Looking Good!

And detail back side. Not much more room!

Look at those large wires. It's going to get busy in there. No room for a 5 or 12v backfeed module.

But with care we make it work. The Top was out for this picture but in place for all the wire bending and fitting. We're looking down at the top - SSR is bolted to the top. Note the front and back are upside down. Don't mix that up! Connections are crimped.

Test it in place. Carefully.

One odd thing I noticed was that the Load LED (the red one) would come on. Not full. But not off. Enough to perhaps confuse.

This is due to leakage through the SSR. There's not much but with no load there's enough to light a 120V (built in resistor) LED. My 40W iron as a load brought it to dimm (SSR off) and anything more quenched it to off.

I thought I had a failed SSR (moslty they fail "closed" i.e. short) until I got thinking of leakage and LEDs and tested quenching it.

Still one must pay attention in bright sunlight. Is it off or is it Memorex (hah). "Off" or "On". Smoker plugged in there's no inbetween.

In my case I found I had the switch poles reversed. So "100%" was "SSR" control and visa versa. I almost always did this. Fortunately I had just enough slack in the wires to carefully remove the switch, rotate it, and tighten it down. Pay attention Mike!

Carefully. If you want then just put screws in. As you do make sure the wires aren't putting too much pressure on the back plates (lots of 14 gauge wires eventually will tweak it). And also make sure no wires are rubbing on any connector nor any screw shafts such as the ground screws (you did ground your case to the cords right? Right?). We don't want any shorts to develop.

And now we're done!

Front / Top View

Back View

I didn't capture any pictures of adding the magnets and mounting. But I'll have some pictures of it and it's first run.

 

[Nauglanch - Mike]

First Run Pictures.

I must say this is a hacked Little Chief. This was a gift from a neighbor and after a couple uses it died. The company said it ws 40 years old and that style heating element wasn't available. So I hacked in (from some web findings) a 1000 watt single burner from WallyWorld. So this is a very high power Little Chief!

Here you can see the Hetermeter magnetically attached to the HeaterMeter Buddy. Well not a great picture of that. But the cables won't pull it apart

This trial run was at 160F to smoke and dry the jerky.

Probe 3 is jammed into the heat sink fins. In a later shot Probe 2 is ambient. You can see the magnet mounting if you look closely.

Side view of the same. So the temp is at the bottom of the heat sink. And at that spot.

Now for the reward

Full setup and you can see the ambient temp probe I added. That way I can see the temp delta from ambient to the heat sink temp

Rewarding! Next we'll discuss some temps.

 

[Nauglanch - Mike]

Some experiments. My main interest was how well the heat sink was doing.

Running at 160 PIT and heating up to that. Ambient was about 85F and the heat sink was running about 15F or so above that. Not bad for a temp differential. Not bad for a high temp.

Next I wanted to run the smoker at 225F and then higher to see how the heat sink did. And max temps of the smoker.

The smoker at 1000W easily got to 225F and the heat sink was running about 20F above ambient.

The PIT set to 275F struggled. I think that's about max for this uninsulated smoker even 1000W and at 85F or so. The heat sink was about 30 F higher.

All said and done - the heat sink, this time of the year, maxxed out at 110F or so. That's hot (hotter than safe in a hot tub). Not scortching. The case was pretty warm. All ok.

If it's 100F outside what will the heat sink be? Maybe just 110F? I don't know. But remember the higher the ambient the less the heater has to contribute and the less the SSR will dissipate. The colder it is the more the SSR has to run but the better the cooling from ambient on the heat sink.

So I'll say for now - Good results on the heat sink. Max 110F or so on the botom of the fins; cooler at the top. I wouldn't want a smaller heat sink. Don't think I need a bigger one.

It's a good thing for the heat sink - the entire thing to be this hot. And the case warm. So for so good. We'lll see later in August and also in the winter.

Enjoy!

Addendum October 2018.

My hacked high power Little Chief blew a fuse. Unfortunately the fuse was slower than the SSR in self-destructing.

The root cause was the power cord connections I made to the hot plate were inside the clamshell. Note that is how it was built and sold. Note also that this hot plate is now captive in an intentionally heat retaining fixture. The power cord wires charred and melted and eventually, through heat induced movement, shorted against ground. This is why you have a ground! This is why you have a fuse!

I repaired this using 1000F MGT wire complemented with race automotive high temp silicone sleeves. This runs to a now remote external electrical box via a box spacer for the external connection to the appliance power cord (it was a 15A appliance cord that was destroyed).

During the run up and test of the repair I noticed the Heatermeter PIT temp kept rising above my set point. It settled in about 285F which I'd previously observed as the max without insulation.

This revealed that while the 10 A fuse had blown - that the SSR had failed closed - a dead short. Note that this is how SSRs, SCRs, etc, fail - they fail closed / dead short. I hadn't tested this as part of the smoker re-wire.

I had a 25A SSR for a max 15A load. OK right? Some in other posts suggest "just get the 40A it's the same size and not much more". That may have helped it survive until the fuse blew. Note that without running full proper heat sinks we're running them de-rated anyway - even with my passive short heat sink.

I found that the largest size that is the same dimension is 50A - with 40 more commonly found. But a 40 or 50A can be found in this same size.

I am replacing the SSR with a 50 A SSR. And ensuring I also have fast blow fuses.

 

[Bryan Mayland]

haha that's really cool looking, that's great how pro that looks with all the switches and indicators on the front. I also agree with you on the cords vs plugs. Once you add those IEC plugs and have all the blade terminals sticking out with possible spade connectors on everything you need three times as much space to get it all in there! I love seeing this sort of extension to adapt HeaterMeters to different kinds of setups.

 

[Nauglanch - Mike]

Hi Bryan, and thanks for the compliment on the build. And we thank YOU with every smoke for all you've done and continue to do for us!

The label makers and some basic masking and painting make it easy to get a good result. And you don't see the touch ups from heavy handed painting.

The concept was SSR in a box with a few wires. Very basic. And I really want somebody needing just a basic Heatermeter Buddy to do just that and not think they need all I did.

But I do like a fuse. Experience taught me the 100% / off / SSR switch was handy (but not required). The banana jacks are for convenience in the shop (who doesn't need a general purpose high power SSR?) And it was very hard to not jam in the 5V back power supply AND a PWM generator to make a truly standalone variable SSR. arrgh! No I'm not OCD but I just like enabling a build in all aspects - and am frequently happy I did. Alas the Banana Jacks the compromise on that. Ha!

Experience also tought me about indicator lights - Before I completed this I "ran" the smoker for 3 hours before realizing it was OFF when using another controller. How's that when the Auberins PID "output" light was blinking? Well I had the same type of switch - 100% / OFF / SSR on that (composite curing oven) controller. And it was set to off. So the PID display was showing it's controlling the SSR - but the load wire was disconnected by the switch!

So for this build I have a basic power light (green) just because there's no other indication (that you didn't pop your outside GFCI - urgh - been there). And the red is connected to the output load wire itself. So if the load socket has power - not the SSR nor SSR control - then you'll know it via that light. So I like these. Reminds me to ensure the switch is set to SSR when I want. I plan on backing hacking a similar indicator into that other controller so I don't make that mistake again.

An enjoyable project. And for me, like many, it's always the journey, and building the HeaterMeter Buddy, for all the time it took, was as much enjoyable shop time as using it with the smoker.

 

[Nauglanch - Mike]

See my edits above about a blown SSR and advise on using 40 or 50A SSRs in the same form factor size. As always - ground and fuse helped maintain safety. Without those the failed closed / shorted SSR would have fed the short in the smoker that caused all the fuss. Fuses! Grounds! and secondarily the highest rated SSR you can fit.