Heating element question

[Doc Harley]

Heating element not getting hot. 12v 3watt. Wired into aux wiring by oil tank.
Not sure about findings, b4 I attempted to dig further.

Note: I run a splitter to heat the element & heated shield. Wasn't sure if that effects output. Does it?

 

[Turboflash]

Output is just split between two. Not sure what max permissible load is on that wire? Does shield work?
Blown fuse?

 

[earthling]

does the element get hot if you wire it on the bench

Your splitter is wired how? In series or in parallel? In series, without the shield you are not completing the circuit, in parallel, both are getting the same voltage so both should heat independently and it should work the same as it does on the bench. But, assuming you are using that heated element for your phone, sandwich, or some other thingy, you really should wire it separately and protect the circuit separately and it should be switched so it does not become an inadvertent battery killer.

 

[Doc Harley]

Output is just split between two. Not sure what max permissible load is on that wire? Does shield work?
Blown fuse?

My secondary question, was just that. I wasn't sure if splitting the one output would somehow effect the overall performance of the shield & heating element.
Kinda like splitting the available power in half, so to speak.

Note: just cuz I own an ohmmeter, doesn't make me an electrician. (I'm being funny)

I'll pull side cover to verify power....

 

[Doc Harley]

does the element get hot if you wire it on the bench

Your splitter is wired how? In series or in parallel? In series, without the shield you are not completing the circuit, in parallel, both are getting the same voltage so both should heat independently and it should work the same as it does on the bench. But, assuming you are using that heated element for your phone, sandwich, or some other thingy, you really should wire it separately and protect the circuit separately and it should be switched so it does not become an inadvertent battery killer.

Off the aux power (battery tender style connection, near oil tank) converted to RCA, on other end, then to an RCA splitter. One for shield & one for heated bag.

 

[Doc Harley]

 

[earthling]

You should be able to read 12v on both connectors. That is in parallel btw. you should read 12v from center tap to external shield on each. Start where the splitter starts, measure voltage there, then move on to the two ends of the splitter. If you have 12v on each, and your total load is less than the fuse capacity, you should be fine. If you have 12v on the one plugged into the heater element, then you should be ok and if the element is not heating up (and fuse is not blown) then there is probably something wrong with either the element or how you wired it to its connector.

 

[Doc Harley]

You should be able to read 12v on both connectors. That is in parallel btw. you should read 12v from center tap to external shield on each. Start where the splitter starts, measure voltage there, then move on to the two ends of the splitter. If you have 12v on each, and your total load is less than the fuse capacity, you should be fine. If you have 12v on the one plugged into the heater element, then you should be ok and if the element is not heating up (and fuse is not blown) then there is probably something wrong with either the element or how you wired it to its connector.

Aye aye.... Ty

 

[earthling]

A simple test would be to put the leads of the heating element across the connectors of a 9v battery. Even a 9v will allow the element to heat up quickly but not as hot as a 12v source will. Don't keep the leads on there too long, just until you can sense some heat.

 

[Doc Harley]

A simple test would be to put the leads of the heating element across the connectors of a 9v battery. Even a 9v will allow the element to heat up quickly but not as hot as a 12v source will. Don't keep the leads on there too long, just until you can sense some heat.

Sorry, I didn't first consider RCA to battery directly. But did as an afterthought, so I did it both ways. 30sec, no heat. Thanks for your assistance. I'll scurry to get a new element, I'd assume....

 

[earthling]

There should not be any issue with polarity in your wiring so yes, it looks like your element may be bad. I should have asked however, how long are you waiting for it to heat up? With only 9v and depending on the condition of the battery it may take awhile, especially if the battery is older. ..minutes anyhow. I duplicated your setup using a nogo genius battery charger running in 13v supply mode. As you can see, the thermal pad pulled the charger down to 6.52v but quickly heated the pad up to 128' F.

 

[earthling]

One note I should add about my experiment is that the heating element tends to overshoot relative to what the controller is sensing. The controller is set to come on immediately and then heat the plate up to 34c (93f). I picked that because I want to heat soak the aluminum plate and the tablet as well. I think the tablet, once it is running, will generate some of its own heat so the idea is to keep the heating plate above the operating temperature of the tablet so the plate never becomes a heat sink. Anyhow, the controller has a thermistor attached directly to the heating element and shuts the element off at 34c but the heating pad continues to rise in temp until it hits about 36.5c (97f) which is curious, not sure why it does that. Figured it out, its how slow the thermistor reacts. Verified with the FLIR that the thermistor temperature reading is behind the actual temperature of the pad by 4-5 degrees. But the whole thing seems to work. It remains to be seen whether it will hold up when it is -20f out.

Plan B is to use buck convertors and a hi/lo/off three way switch and just set the buck converters (one on hi side, one on low side) and target specific temperatures. Plan A is self regulating, Plan B is not which concerns me some. Will have to play around a bit and see.

 

[Doc Harley]

There should not be any issue with polarity in your wiring so yes, it looks like your element may be bad. I should have asked however, how long are you waiting for it to heat up? With only 9v and depending on the condition of the battery it may take awhile, especially if the battery is older. ..minutes anyhow. I duplicated your setup using a nogo genius battery charger running in 13v supply mode. As you can see, the thermal pad pulled the charger down to 6.52v but quickly heated the pad up to 128' F.

View attachment 169566

Well done.... Battery is brand new but will retest element for longer duration.
I have a charger and can mimic your power supply idea to power the element that way.
Many complains on Google in regards of 12v 3w heating element not putting out enough heat on those extremely cold days.
I like the idea of buck converter. Never even crossed my mind. Excellent idea.

Note: also have a temp gauge to verify. And do understand your draw concerns

 

[Doc Harley]

Well....my charger is charged and showing 16.5v, once I hooked it up to element the temp started to climb from 65° to 71°. At the same time my charger went into a safety protocol and stopped.
I'll have to grab my 12v battery from my lawn tractor, charge it, and retest.
I'll get back....

 

[Stubbs]

Well....my charger is charged and showing 16.5v, once I hooked it up to element the temp started to climb from 65° to 71°. At the same time my charger went into a safety protocol and stopped.
I'll have to grab my 12v battery from my lawn tractor, charge it, and retest.
I'll get back....

View attachment 169568

Cordless drill battery can be a handy power source for tests like this, just don’t leave it hooked up for prolonged periods of time if it’s an 18 or 20v unit.