Thermocouple and 12v Battery advice! Please


 

ARowe

New member
So Ive got everything ready for my first cook on my Kamado with my heatermeter!
I've got a couple of queries before I start.
The weather in the UK is abit rubbish so could rain and turn cold even after tropical (to the UK) weather. So I was thinking of running a 12v battery and thw whole thing in a waterproof hobby box with a tupperware tub modification for the rotodamper for now. Do I need to put any fuses in the 12v line before I attach a leasure battery?
Also I bought a bare junction thermocouple by mistake so if I was to wrap the end in heatproof Teflon tape to cover the exposed end then make some thermal mass say a stainless nail wrapped around the end with some aluminium foil? Just until I can get my new thermocouple ordered!

Thanks for the help
Looking forward to posting some live cooks soon enough!
Andy
Leeds
UK
 
Nothing special needed to run off a battery. The thermocouple will also be fine. The end will be welded, so I doubt the fire will be hot enough to break the weld. Sticking it inside a ball of aluminum foil could might help with a smoother temp reading though.
 
If you deal with rain a lot you might want to rig your probes so you can send them through the CAT5 cable to the HM, that way you can keep the HM away from the grill (about 50ft max) to keep it and the power supply out of the rain. I posted details about this in the RotoDamper thread.
 
Cheers guys! Ralph I did look at your board it may be a future upgrade once I've got a new soldering iron!
With the thermocouple I was panicking about the metal getting knocked onto the grill and causing a short
 
Use the proper extension cable for thermocouples

always use an extension cable when using thermocouple that match your current probe. thermocouples are 2 dissimilar metals that when the ends are fused together will produce a voltage that has a traceable curve over a range of use. All couples have a curve for a range of use. If you want to extend and do not use a cable made up of the same conductors as the couple your using, the probe not becomes in accurate and the signal will not match the curve for the probe. the longer the extension the more the error. when connecting the extension to the probe, you must use the connectors that match your probe to make sure you keep the sensor again accurate and matching the probe curve. RTD`s are resistance devices and are not effected like thermocouples are when you extend the cable. You can find these extension cables at Thermoworks for around $30 us. Make sure the cable is the same type as your probe.
 
If you have a standard pit probe you can send it and food probes over standard CAT5 cable without issue. If you have a thermocouple pit probe you do have to use proper TC cables, either connected to the HM OR connected the the RDTC Aux thermocouple board, which can send the thermocouple output over standard CAT5 cable to the HM without issues.
 
Would I have to wire anything different on the heatermeter side? I dont have a soldering iron at the moment, I've got the thermocouple set up, Bryan kindly soldered my heatermeter together for me, I'm just waiting for my 12v adapter! Then hopefully I can cook today or tomorow, but as usual it's raining here at the moment!
 
I've used some bare thermocouples and thought they were way too sensitive and caused the temperatures to jump up and down by a few tenths of a degree on every update which made it a little difficult to control the smoker. I put a piece of kapton tape over the tip then put it inside a piece of metal tubing and crimped it by squeezing it with pliers.

It is ok if it shorts against something to ground in that it won't cause any damage to the circuitry, but you will see the values start going nuts when this happens. It can't run like that, but at least it isn't going to break anything.

Finally, I've used a 10 year old 7.2Ah 12V battery from an old UPS (that said the battery was no good any more) and it lasted more than 24 hours. The HeaterMeter power input works up to 24V, but when the blower first turns on it gets the full voltage of the power supply for a split second so it's not a great idea to drive it with more than say 15V.
 
Would I have to wire anything different on the heatermeter side? I dont have a soldering iron at the moment, I've got the thermocouple set up, Bryan kindly soldered my heatermeter together for me, I'm just waiting for my 12v adapter! Then hopefully I can cook today or tomorow, but as usual it's raining here at the moment!

You do have to add jumper wires on the HM from the four spare pins of the CAT5 jack (HMv4.3 has holes to solder in jumper wires) to the probe jacks. For the Thermocouple you need to either lift one resistor from the board and insert the external TC there (which will disable the onboard TC amp), or you can add a switch and connect both internal and external TC amp and use the switch to select which one you'd like to use. I've been using this setup for years now and it works extremely well.
 
Cheers for the help! Bryan I used some electrician's tape and then made a cylinder outof of a few layers of aluminium foil, works well doesn't flutter as much!
Ralph, Il look into your method once I've gotten everything up and running smoothly, I'd have to order the part for the rotodamper!
 

 

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