This didn't belong in the fluxer thread;
here
As the (3) 18650’s voltage slowly drops, the 1st DV click timings will slowly grow as well. If you get 1st click at 4-5 seconds while batteries are freshly charged at about 12 volts, after much use, and total voltage drops to 10.6 volts, the 1st click will take longer, 7-?, (I’m still testing), but longer 1st click times are another clue, besides battery voltage, that it’s time to charge batteries. BTW: Fluxer’s with battery life switch/LED, the green-green/red- red LED’s, are surprisingly accurate indicators of remaining battery life.
The tuning of the circuit, the part that Mr C does in design, determines the power level that affects heating. Speaking on generic modules, which act similarly, yes. And I'll provide the caveats to this observation. It may also help to understand the Fluxer/Flix coil choices.
Please note that I started and have used the stock ZVS circuit coils for a long time. The are open and airy. This is the intent of an induction heater to generate its most efficient magnetic field. Very 'forgiving' coil. Insertion depth didn't matter much because the entire cap was bathed in a fairly homogeneous magnetic field. Settling on 60 watts as a good heating rate, I enjoyed that setup immensely. One little niggle - it also vapes the resins in the cooling fins making for crumbly deposits that don't wash away easily.
I started working coils to see what happens. Mostly I was interested in the circuit variation but I quickly learned to mind the size of the magnetic field. I quickly figured out that small also means less 'generic'. I went down to a 16mm ID on a short coil and learned that 2mm can take the load from green taste to burnt. A slightly longer coil improved that but still very sensitive.
I still fire with 3 coils at the moment. I can manage any of them. However, they are not 'right' to my tastes. But that doesn't matter as yet. However, I am not one to make an aggressive coil the standard. I'd rather have more margin on time. 8-10 seconds heatup is a good balance or me. If I crank that output up to 12V, it'll double click in 5 seconds with any of the coils.
By the same token, I got the click to change several seconds by moving the cup in the smaller coils. This is where I started to notice these were not quite as forgiving. They draw the same power but the intensity of the field is no longer as homogeneous as before with the longer coil. So the clicker is 'left out' It isn't being heated by the magnetic field as much and the temperature must migrate from the hot spot on the cap to the clicker. This can loosely be associated with hysteresis in a 'circuit' but it is compounded by the fact that the magnetic field's influence on heating the clicker also changes when you move the cap within the coil. Double whammy. Therefore, effect-by-the-millimeter is device dependent. In the discussion so far, I am fairly confident that a millimeter of movement of the coil in relation to the VC can have a 2-3 second change in timing and cook time based on the Fluxer/Flix design. This time difference will decrease as you enter the margins of the usable range.
I happened upon those battery meters. I put one in my flat-pack IH. That little HalfPint is running high on the list of favorites. That is the unit that is teaching me about recognizing a low battery charge based on performance. At 9V under load, it never reaches the second click before dipping below the minimum voltage. 9V is the typical safety cutoff for 3S li-ion. I think it is running at a 35 watt range at that time. Therefore, since the cells ae sized for my daily use, if toward the end of the day if starts to lack performance, I should know intuitively where my cells charge state is just by using it. It also means I've overdone my day and I should just lay down the VC.
Nice write up TommyDee.
Having only my SKJ IH previous to my FD, I’m curious what if anything is used on IH units like the Apollo, to keep the hot DV tip, from the push down switch? As you know the FD has a tiny glass button glued to the top of the switch, so it can’t melt. Do the commercial IH devices use the same or similar switches, and are they left stick/bare?
Thanks.
I think the VC-activated switch is the genesis of each of the artisan heaters. They all had to deal with it. I've simply (a)voided it. This is not a simple problem. My take is an offset switch with an actuator in the bottom of the coil. Regardless, there is a lot of heat. I'm settling for wooden cups and I'll need something like Oak to keep it from continually charring.
I believe that these switches have also complicated the usefulness of making the VC position in the coil adjustable. I think the relationship should be adjustable.
Let me give you a fun alternative to the switch for design... What about 2 flexible contacts as a switch? Let the cap complete the circuit.
Come to think of it, if those contacts were on an adjustable pedestal, one could adjust the insertion depth as well. You can use aluminum around the coil for hardware.
View attachment 1515
Sorry, thought you had an Apollo at one point. I’ll see if I can find a photo online, or perhaps someone that has one can reply?
As far as using the cap to make the circuit, it was either in this thread or the old one, if you recall someone tried something similar, but the metal acted as a heat sink, so NG. Seems if the switch is going to at the bottom of the coil, it needs some type of non metal insulator. I know Mr. C, looked long and hard on this subject, thus I was interested in how other builders, especially the commercial ones, have approached this issue.
@RustyOldNail It look like it's a silicone cap at the bottom of my apollo. It's the same thing on both models.
View attachment 1518View attachment 1519
Yes, Apollo uses a silicone switch button.
I suppose a pair of pogo pins would eliminate the heat transfer. I'll play with it some.
Also, there are metallic RF-compatible materials. When I put my hobby knife handle in the IH it only pulls an extra 3 watts. That says aluminum will work.
We should move this discussion to the generic IH discussion thread though..
@Stu ?
Thank you for taking your time to take photos & post! That’s very interesting, wonder what temperature that silicone is rated for? The switch on the FD is high temp rated, but from my limited understanding, most of the custom coil choices Mr. C offers can run hotter, then the types used in many of the commercial ones, and thus if a DV sits too long on a bare plastic/composite switch, can melt it, (photos in this or OGFC thread). The glass button solution he employs works great. I was just curious. Thanks.
Switch boots.
metal dome switch
Okay, back to Fluxer...
I found the image you were talking about... Is this it?
View attachment 1520
... this is my interpretation of the "half pint":
But, thanks for making me think about it. Maybe I'll have to get on that's specially shielded somehow!
Beer? 
That just looks super cool 