Low Voltage Induction Heating technique - Page 1
Forum section: electronics / beginners

author: sirish
author_rank: Newbie
timestamp: January 20, 2017, 10:27:55 pm
content: Hello all,I'm trying to make a product that heats to temperature up to 250degC. I've explored resistive heating technique and it seemed the simplest. I stumbled across Inductive heating technology and was intrigued by how its a contactless technique. However I am not able to find any inductive technology products that operate from a Li-ion battery, 3.7V. Don't know if its a technology limitation.Can anyone shed some light to get me upto speed ? The reason I'm trying to choose other options from resistive heating is the battery dies pretty fast and have to constantly recharge. So any technology that conserves energy.ThanksSirish

author: Brumby
author_rank: Unknown
timestamp: January 20, 2017, 11:18:19 pm
content: Resistive heating is, indeed, the simplest. It is also highly efficient. If we ignore the losses in the battery and wiring (which are going to occur in any solution), the power dissipated in the resistive heating element will be converted into heat with an efficiency of 100%.That's rather difficult to beat, unless a different approach is taken.The only alternative that I am aware of which can deliver greater efficiency is by way of a heat pump. Common examples of which are refrigeration and air conditioning. A 3.7v Li-ion battery is not going to cut it.If frequent recharging is your problem, I would suggest a higher capacity battery arrangement - with multiple batteries.

author: Benta
author_rank: Super Contributor
timestamp: January 20, 2017, 11:27:48 pm
content: As it seems to be a great secret whether the object to be heated is one cubic metre or perhaps only a cubic millimetre, it's hard to say.It's always entertaining to be presented with half-questions.Inductive heating really only works with ferrous objects, by the way.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: January 21, 2017, 01:19:36 am
content: How much power? How fast? What is the material? Battery life required?Quote from: Benta on January 20, 2017, 11:27:48 pmNah, it's fine for anything conductive -- but what's critical is having the coil close to the work being heated. "Non contact" is technically true, but many applications need a coil very tightly tailored to the part!Tim

author: IO1973
author_rank: Newbie
timestamp: January 21, 2017, 08:54:02 am
content: Quote from: sirish on January 20, 2017, 10:27:55 pmThat sounds interesting. Would you mind sharing some more technical details? I'm thinking of making something similar but I couldn't find anything interesting online.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: January 21, 2017, 09:00:44 am
content: Quote from: Benta on January 20, 2017, 11:27:48 pmit works with non-magnetic, conductive metals, but you need higher frequency and closer coupling.Induction heating requires high currents in the work coil, which is why you generally need to start with a fairly high voltage, typically driving an LC resonant circuit.You need to tell us more about the application to know if it's practical, but you're not going to get anything bigger than a few grams to that temperature with a a single lithium cell

author: sirish
author_rank: Newbie
timestamp: January 23, 2017, 01:45:23 am
content: Oh no Benta. There's no secret here and I'd be more than happy to provide any further information. I just didn't know what further information was needed.Its a thin hollow cylindrical stainless steel product that I'm planning on heating. radius 1.9mm, height 12.6mm, with a volume coming out to be around 143 cubic mm. It'll contain a thermoplastic material inside that gets heated.I did read that inductive heating is good for some non-ferrous objects too. It might take longer, but that's not a problem for me as long as the technique works.

author: Neilm
author_rank: Super Contributor
timestamp: January 23, 2017, 06:43:56 pm
content: Quote from: sirish on January 23, 2017, 01:45:23 amStart by getting the mass of what is heated. Then calculate how much energy is required to heat it to the temperature you want (I think steel is about 450 joules .kg/degC). Compare that number to the engergy stored in your battery and that will explain why your battery discharges so quickly.

author: james_s
author_rank: Super Contributor
timestamp: January 25, 2017, 06:11:40 am
content: I think the easiest approach by far is going to be resistive, induction heaters aren't really practical at such low voltage. I would consider putting a layer of polyamide around the cylinder and wrap an appropriate number of turns of nichrome wire around it.