Buck & boost

[Zutankhamun]

''Look into how buck and boost converters actually work to get a better idea of what's going on.
Put simply there are basically two power circuits one going in will have the voltage of whatever the battery is charged to and a variable resistor (potentiometer) will pull the correct amperage to give you the set wattage. The converter will then change this to a lower or higher voltage with higher or lower amperage respectively in order to reach the wattage set.''

I was looking into the amperage drawn from regulated devices. Could somebody please explain in layman terms how buck & boost works when you run a 1 ohm build at both 20 & 100 watts (or a high wattage that your limits allow). Thank you

 

[edyle]

buck and boost merely refers to the circuitry that allows you to change the voltage to the coil.

 

[Zutankhamun]

K thanks. So using vapecalc is still correct without amendments? it says 4.47 for the 20 & 10 Amps for the 100 watts. That is correct

 

[MorpheusPA]

When you run a 1 ohm coil off the battery, it's going to try to pull around 3.7 A naturally, on average--about 14 watts, changing as the battery discharges.

When you run it at 20 watts setting on your mod, the device converts the battery voltage upward to push 20 watts through the coil. When running at 100 watts, the device turns the voltage up much further.

If you ran under what the natural draw would be, the device converts the voltage downward.

Right now, my battery is at 3.9 volts, but I'm vaping at 3.2 volts. My device is converting the battery voltage down to 3.2 so my coil draws a smaller wattage.

4.47A for 20W and 10A for 100W is correct. The equation is Watts = Amps * Amps * Resistance.

So for 20, 20 = 4.47 * 4.47 * 1, which is correct.

 

[Ryedan]

I was looking into the amperage drawn from regulated devices. Could somebody please explain in layman terms how buck & boost works when you run a 1 ohm build at both 20 & 100 watts (or a high wattage that your limits allow). Thank you

MorpheusPA explained it well Zutankhamun. I'll just add that a boost regulator can only increase the voltage of the battery and a buck regulator can only decrease it. There are also regulator circuits that are able to do both.

If the regulator in your mod can not deliver the voltage needed to make the watts you set with your resistance, it will either fire at its voltage limit without giving you the watts you asked for or it will refuse to fire. Battery amp draw will be determined by the watts it fires at.

 

[Mike 586]

K thanks. So using vapecalc is still correct without amendments? it says 4.47 for the 20 & 10 Amps for the 100 watts. That is correct

Well at 20W that's what you should get on the output, what's drawn from the battery will be a little different, but not really something to be concerned about.

At 100W, with most mods you're just not going to get 100W of output, most mods can't boost the voltage to 10V. The screen might simply list what theory says it should be doing but at best you'll be getting 90W if that.

Anyway, I'm not sure where you dug up that first description of a DC-DC converter circuit. It was written by someone who hasn't even the slightest clue on the subject.

These are about as simple, straight forward and consise an explanation as I've ever seen, just keep in mind the examples being used are the bare bones basics of DC-DC converters. Dave Jones of the EEVBlog has at least a couple of hours worth of videos just about DC-DC converters, though his stuff is geared towards people already well versed in the theory.





There are just two things you want to avoid with regulated mods if you're looking to have them last for ages. High currents and buck/boost levels too far from the source voltage are what you want to avoid, particularly with higher power mods.

With mods like the DNA20 through DNA40 and most of the better 50W boards, you can probably get away with running just about anything on them indefinitely. As you get past that point to 60W+ mods on single batteries and 150W+ on dual 18650s, manufacturers have been forced to make more compromises in design and staying in the sweet spots becomes more important.