Official DNA 40 introduction

[sedge]

Doesn't 30 watts draw the same amps no matter what the resistance is on a regulated device?

That is what Brandon said when he was at ecc. I thought the old rule of thumb applied like with variable voltage where battery life is extended with higher resistance builds. I asked what the optimal build was to extend battery life and he said it didn't matter. Watts in watts out on an evolve regulated device.

 

[350ZMO]

Ohms law still applies but it applies to every component in the dc to dc converter. And so do the rest of the laws of physics, namely conservation of energy. Think of the dc to dc converter as a black box full of components but you don't know what. If you did, you could apply ohm's law to every component in the converter and arrive at the answer. There is a simpler way. Power in must equal power out + power lost due to inefficiency. It can't create energy. If you need more voltage to make the power at a given resistance than the battery is at, the dc to dc converter draws more amps and converts it to voltage and vice versa. But power in == power out plus power lost due to inefficiency. I think I read some where the DNA40 is 95% efficient. So if you are drawing 30W from the battery, then 5% or 1.5W is lost in heat in the dc to dc converter. There will be other losses in wires and connectors ignore those for now...the point is the atty would get about 28.5W. The converters have limits, it can't convert if the supply voltage is below a certain limit. It can't convert if the supply current is below a certain limit. It can't create a voltage or current higher than it is designed to, hence the ohm limitations and battery it needs in terms of current and voltage at load.

But the point of the DNA40 is temperature control. When it calculates the coil has reached a certain resistance, it throttles the power going to the atty.

 

[gray]

I'm not sure I understand your response.

You still control the wattage output, with temperature as a limit that you can set. That I understand perfectly.

But regardless, to output 30 watts on a 0.1 ohm build must necessarily draw more current than 30 watts on a 1 ohm build.

A little more clarity is appreciated.

ETA: I guess it'll be different in the sense that with the dna40 we won't be dumping 30 watts throughout the firing time once the temperature limit kicks in.

At the battery, say it is at 4V, then 30W will require (watts = volts x current) 30/4 = 7.5A. There are small converter inefficiences so it will probably draw around 8A.

On the coil side, the 0.1 ohm coil will get 30W of power. Power = volts squared/R or Power = current squared x R, that gives us 1.73V and 17.3A to the 0.1 ohm coil. But as the coil heats up its resistance will approximately double, so the volts and amps will change in unison.

That is what a DC-DC converter can do, that is, to take voltage and current from a battery and convert it to a different voltage and current to power the coil. Voltage x current = Watts. Here we have 30 watts taken from the battery and 30 watts delivered to the coil, but in different numbers of volts and amps. The battery life is unaffected, the battery is simply driving a 30 watt load, it doesn't know there's a 0.1 ohm coil or whatever on the other side of the DC-DC converter.

That's a pretty good answer.

People may miss the fact dna40 can step down to 1v output. A full battery of ~4v into .1Ω doesn't work well for a mech or the dna30. Lower voltages into .1Ω is not a problem for the dna40 and it stays within the defined amperage limits.

Note on the coils:
I'm starting with 9-10 wraps of 32ga NI 200 on a 3mm coil or 7-8 wraps on 30ga. I'm finding the steam engine "results>heat flux" field handy to compare with the builds I already have.

 

[KenD]

Note on the coils:
I'm starting with 9-10 wraps of 32ga NI 200 on a 3mm coil or 7-8 wraps on 30ga. I'm finding the steam engine "results>heat flux" field handy to compare with the builds I already have.

What resistance are you getting on those builds? And I'm assuming that would be for single coils?

 

[brickfollett]

Does anyone know if the VaporShark rDNA 40 is shipping right now? I ordered one and the website says pre-order all over it, but I saw someone earlier that said his was showing up on Friday.

 

[gray]

What resistance are you getting on those builds? And I'm assuming that would be for single coils?

.35Ω and .18Ω. Yes, single coil. This is just a starting point.

 

[peraspera]

Does anyone know if the VaporShark rDNA 40 is shipping right now? I ordered one and the website says pre-order all over it, but I saw someone earlier that said his was showing up on Friday.

When you put an rDNA in your cart it shows a ship date of October 28. The ship date does not show on the order page nor on my receipt. Also, Vapor Shark's home page now has a banner at the top that reads, "Shipping Notice: Please allow 10 days processing for all DNA and rDNA orders."

I ordered the charger thingie and a Shark Skin and got a shipping notice immediately so that is very likely what was shipped rather than the rDNA40 itself. I actually placed my order very early in the morning (9:00 am EST), hours before VS announced availability on FB, so I would be quite surprised if any of the rDNA40s ship before October 28.

 

[gray]

That would be a stretch. Maybe it was just a shipping label print notification. Hopefully they have picked up the pace. People are experiencing several days between order to actually shipping for the 30.

 

[brickfollett]

When you put an rDNA in your cart it shows a ship date of November 28. The ship date does not show on the order page nor on my receipt. Also, Vapor Shark's home page now has a banner at the top that reads, "Shipping Notice: Please allow 10 days processing for all DNA and rDNA orders."

I ordered the charger thingie and a Shark Skin and got a shipping notice immediately so that is very likely what was shipped rather than the rDNA40 itself. I actually placed my order very early in the morning (9:00 am EST), hours before VS announced availability on FB, so I would be quite surprised if any of the rDNA40s ship before November 28.

I think you mean October 28. Just double checked the website, had me sweating there for a minute!

 

[peraspera]

I think you mean October 28. Just double checked the website, had me sweating there for a minute!

Thanks much. Edited the date so as not to cause mass hysteria among those who preordered the rDNA40.

 

[Rossum]

Did you order one Rossum?

Yes. In theory I should have a DNA40 board tomorrow, but it might be Sunday before I actually get it installed.

 

[brickfollett]

Wish I had the tech skills and time to build my own. That's what full time work does though I suppose

 

[KGie]

Wish I had the tech skills and time to build my own. That's what full time work does though I suppose

That, plus gives you the resources so you can buy pre-built and don't have to build your own.

 

[brickfollett]

That, plus give you the resources so you can buy pre-built and don't have to build your own.

Yeah but I think I'd still have to solder wires and such, which I have a zero skillset for besides non critical solders on my truck

 

[Phone Guy]

I have a question about temp control, explained in plain english or broken down in to more simpler terms.....

Wouldn't using temp control negate watt control?

How do you get 40w and still retain 450 temp (as an example)

 

[Bassnorma]

Yes. In theory I should have a DNA40 board tomorrow, but it might be Sunday before I actually get it installed.

What are you installing it in?

 

[KGie]

I have a question about temp control, explained in plain english or broken down in to more simpler terms.....

Wouldn't using temp control negate watt control?

How do you get 40w and still retain 450 temp (as an example)

Doesn't negate it, it limits it. You'll get whatever wattage you've set, as long as the temperature is under the limit you've set. Once the temp hits the limit, the wattage will be dialed down to keep the temp at the set limit.

 

[finagle69]

I have a question about temp control, explained in plain english or broken down in to more simpler terms.....

Wouldn't using temp control negate watt control?

How do you get 40w and still retain 450 temp (as an example)

I'll give you a car analogy.

Temp is like Velocity (speed). Watts (power) is like Acceleration.

When you use a VW device now, you're constantly adding energy. Watts is defined as a rate of change of energy. So there's not a constant amount of energy being put into the coil really. It starts dead, then gets hotter and hotter, eventually getting too hot and can degrade juice and/or burn wicks.

Putting a Temp limit is like putting a Speed limit on your car. You can apply as much Accel as you want, but once you get to that set Speed, you'll stay there.

The trick is to find a balance. Too small of an Accel and you may never reach your speed limit. Too low a speed limit, and it'll be too slow (cold) for your liking.

They work in conjunction.

 

[Bassnorma]

I have a question about temp control, explained in plain english or broken down in to more simpler terms.....

Wouldn't using temp control negate watt control?

How do you get 40w and still retain 450 temp (as an example)

When you set the temp and the watts, It will peak at the watts you set while raising the temp of the coil...There is a HANA ModZ review that kind of shows that....will edit post when I find it...,

Pardon this guy...he is a little spastic. Sorry if any of you are actually this man. I get that it is a web persona...LOL

 

[p7willm]

I got screwed up on the whole amps and watts with a regulated device. Until it hit me. Think of it as 2 different circuits. One is the battery and the regulator and the other is the regulator and the atty.

The battery/regulator circuit is at battery voltage and the regulator/atty is at whatever voltage you need.

The thing that does not change, except for a small loss in the regulator, is power (watts) if you have 30 watts on one side you will have 30 watts on the other.

A 1 ohm coil will take 5.48 volts and 5.48 amps. The battery is at 4.2, when fully charged, so it will take 7.14 amps and the regulator will have a resistance of .59 ohms.