John

Just to throw this into the discussion... You can use Escribe to limit the max and preheat power, and use smaller cells. A device limited to 80 watts could use a 2s 600mah pack easily.

There's a better way to do this. Get a decent thermometer or thermocouple, a glass flask, a heater (or do it on the stove) and some oil. Run wires extension wires (kanthal is best of the easily available stuff, it has a very very small TCR) to the coil and back to the DNA 200. Fire up atomizer analyzer. Short the kanthal together at the far end to get the resistance of the kanthal and mod. Then connect the kanthal to the coil under test. Put the coil in the flask, fill the flask with the mineral oil and put the thermometer measuring the oil temperature. Put the whole apparatus on the stove. Don't start a fire. Use an oil with a high flash point and low conductivity. Silicone oil works best, but it is a bit spendy. Transmission fluid works if you keep it under 450F or so. You can use this sort of setup to generate a TCR curve for anything with a little care and practice. The oil is easy to measure, and it keeps the coil at a nice uniform temperature. Stir the oil so you don't get hotspots and don't set your thermometer on the heated bottom.

YiHi does temperature control a little differently than we do, so for an identical setting, even running well they will be somewhat warmer. What they do is put in some power, then stop and wait until the wire has cooled back to the setting, then put in some more power. So whereas we're always dancing around the setpoint when running correctly and limiting (a few degrees above, a few degrees below, back and forth) they're more of a shot up above the setpoint and a slide back down to touching it, then shoot up again. But it shouldn't be staggeringly different. If you're having to run at 580 degrees to get good vapor I'd be very suspicious that there's something going awry in the 200 build somewhere. If you calculate what the coil should be (steam engine, perhaps) or measure it independently (milliohm meters are expensive but great for this) and then compare the results to atomizer analyzer that would go a long way towards telling you where the setup is being questionable.

It won't hurt the onboard balance charger to charge from an external port. It will probably make your battery meter wrong for a while, though, until it charges up enough to think you swapped packs.

Low lipo charge shouldn't cause it to stay open. If you disconnect the battery and go into device monitor with the newest firmware and escribe, does it show your fire button as being pressed?

Just figured I'd pop in and give you all a heads up why I haven't been on the forums the past few weeks. Back in April we applied for this NIH program https://www.fbo.gov/?s=opportunity&mode=form&id=cd2c77ea70aca289dc5da566adb1510a&tab=core&_cview=1 to develop a standardized research e-cigarette, and Evolv is one of the finalists. I've had to put development efforts on that into high gear, as well as spend a lot of time researching and responding to various requests from NIH. They want to award early and then on top of that they want to compress the timeline further if possible. The grants aren't for a lot of money, but it is really important for the industry for us to get this right. If vaping is going to survive, it is because we are demonstrably healthier than smoking. Demonstrably doesn't mean "I tried it and I feel better" and it doesn't mean RJR commissioning a study. It means actual medical researchers running actual medical research. Most of the e-cigarette studies that have been done thus far have been crap. Honestly, who can blame the researchers when the only tools they have are off the shelf devices. Nobody expects cancer researchers to work with X-ray glasses purchased from the back of a comic book, but "we went down to the local convenience stores and bought some Blu e-cigs" is the best that they can do right now. Getting really well controlled, accurate, instrumented, documented devices that record and report into researchers' hands will let them draw accurate conclusions. For example, formaldehyde: you really can set up an e-cig to be a formaldehyde generating machine. You can also set them up to give you virtually none. The questions that really should be asked are "what controls formaldehyde production, where is the limit, and are people actually getting formaldehyde in day to day use" but until they have a good research device, that isn't an answerable question. (Incidentally, the answer to those particular questions seem to be "Temperature, somewhere between 430F and 450F" and "yes, but only some people.") Also, this is NIH. I have a TON of respect for the National Institute of Health. This solicitation was the only one that I felt was asking the right questions, and I'd really like to see the people asking the right questions get rewarded with the best results. FDA is running a similar development and we did not apply for that one. "The government" is not monolithic. You can see a lot of hints of this work in the 200. The device we're proposing as the standard research e-cigarette is not the 200. You don't need to pay for an accurate clock, megabytes of data storage or extra sensors. Researchers don't need to pay for 200 watts. It is 100% an Evolv product. Just in the course of developing and characterizing this research e-cig we'll be able to put a lot of unanswered questions to bed. I think I am over the most time-critical portions of it (the actual device development and research I enjoy, the reams and reams of forms, paperwork, proposals, counter-proposals and all that... not so much) so hopefully I'll be back around here with more regularity. I'm happy to talk about this to the degree that I can.

Be extremely careful plugging it into your car - your alternator can be putting out as much as 14.5 volts. If it is set to 3s and you plug a 2s into it it will not fire. It will fire and charge with a 3s battery if it is set to 2s, because it can see there's an extra cell there. It will fire regardless of input voltage (and will never charge) if it is set to power supply. It will do so without regard for itself: it will happily blow fuses or try to fire from 4 volts or 15 volts or any other horrible things you might try to make it do. SO be careful what you feed it

Is that board the working one or the non-working one? It looks like both the capacitors that should be there are on that board.

Unfortunately USB is a differential signal, it has to be routed with somewhat more care than typical chassis wiring. It would be an absolute minimum of six wires too. Not impossible, though.

Can you post a device monitor screenshot of your dry puffs? With temperature and power displayed. You shouldn't ever be getting dry hits, unless something isn't cooperating or you have the temperature set too high. Looking at the graph should show us what's up.

Something like this would do the trick http://www.amazon.com/Chassis-Mounted-Aluminum-Wirewound-Resistor/dp/B008IE2IWI/ref=sr_1_1?ie=UTF8&qid=1439235466&sr=8-1&keywords=1+ohm+power+resistor

We've seen at least one chinese chip claiming temperature control by the "vape through a tank, then it will stop when you get to that amount of energy next time" which was pretty cheesy. I know one Chinese manufacturer are experimenting with a thermocouple welded to or pressed into the coil. That's very tricky from a time constant standpoint (I have thermocouples that will do it well, but they're thinner than a human hair so they aren't really suited for a commercial product) but is a perfectly valid general approach. The devil is very much in the details. I know of one who are just running an output power profile and calling it temperature control. There are other ways of measuring temperature too. I imagine we'll see a number of them tried at some point. We went with our method because it has the fastest response time and is compatible with existing tanks and atomizers. In terms of flexibility, we have a fair amount of code space and ram left. So we can (and have been) adding things as they come up. Sure, we could sense dry-out, but if the temperature control is working well would you rather have a device that lets you milk your last few drops of juice at a lower wattage as you drive on a long car trip, or one that says "nope, you're done, refill me." I can't imagine why PWM would be useful. We've been true DC-DC all the way back to the Darwin. The hardware could be made to do it, but it would be a massive step backwards for no benefit I can see.

What do you need that isn't covered by James's post on the previous page?

AH! You can do that already. The option is on the Research tab.

Sure, we can do that. Is everything reasonably easy to get to on it?

The coating is silicone. http://www.customadvanced.com/printable-chemical-resistance-chart.html is a reasonable chart for general chemical resistances. It'll resist acetone for short periods, and acetone evaporates very quickly.

combatwombat, is there any change you have a big power resistor around somewhere? Or feel like winding a gigantic (half inch diameter, maybe a foot of wire, 20 gauge) kanthal air coil? I'd be VERY interested to have you run battery analyzer and see what the actual response and capacity of your battery is. It may or may not match the default ones we've tested at all.

It sounds like you have one cell with a fair bit more capacity than the other two. How many watt-hours does it think the battery has left when two of the cells hit low voltage cutoff? This doesn't necessarily hurt anything if you're getting the full rated capacity of the pack. You expect some differential falloff at the very end of charge, but .6 volts is excessive. .2 or .3 from low to high at the low voltage cutoff would be perfectly normal, though. Protovapor have good customer service, so if the pack is a problem I imagine they'll take good care of you.

Set to power supply mode it ignores the battery taps entirely and won't charge. What's the use case here? There are better ways to do this depending on how exactly you plan to use it.

I guess the big question if, if you make a DNA 40esque chip with an integrated charger and Escribe, where do you put the USB port and charger?

well, that's an 0603, so a little larger, but it'll work just fine if you get it soldered on.

Well, no. It will work cables making intermittent connections, though. So there's that.

Ah good. Keep an eye on it, but if the newest firmware made it start cooperating, and the mod isn't getting unusually warm, then excellent! Warranty service really means it is running out of calibration for one reason or another.

Not with the 200, it needs an absolute minimum of 5 Volta to run.

Thanks for the excellent writeup! This should help a number of people.