VapingBad

It is very simple high school electronics replacing the highest potential cell with a short is closing the open circuit it's removal would cause connecting the 2 cell to the board in series, it would also connects the highest 2 balance taps together to the highest potential from the cells as the highest one is not applicable for a 3 cell operation.

No, shorting the connections for the missing battery.

Also consider the much larger capacity of 3 2500 mAh 18650s should work in there favour, being 2.75 times that of the LiPo I used and the current capability of an equivalent capacity LiPo would be 2.75 times.

Only 140 W as the coil I had handy for the battery analyser was 0.557 ohm and the power limit for that is about 145 W, I'm sure it would look even more dramatic if I used a higher power and newer LiPo let alone a 90C LiPo. Same charge level, same fire duration 5 seconds, same coil, though the LiPo has had a lot more charge cycles that the VTCs, the LiPo is only a 30C rating 900 mAh.

Limiting the wattage is limiting the input side of the circuitry and not at all arbitrary IMO. In this case that is for safe and full use of a 3s Li battery, they allow down to 3.1 V per cell rather than your mod only performing as stated with a fresh battery. The voltage limit is again from the battery and it being a step down converter. The current limit is hardware, as this is what makes the internals get hot.

This came up elsewhere, but thought I should also put it in this thread. Kanthal limits from R = P/I.I = V.V/P (I think if you want to convert to temp limiting numbers you would use to the hot resistance to match to a row on this table, not 100% sure I will run the numbers with Ni sometime to check.)

Kanthal limits from R = P/I.I = V.V/P

Just for you Mike, Kanthal limits from R= P/I.I = V.V/P

The resistance does not directly dictate the power rating, it is the max & min output voltage & current and resistance that do. You may know, but think watts on both sides of the board with a <=3% conversion loss, at 200 W output the board needs a fraction above 206 W from the battery, at min voltage (9 V) that is 22.89 A regardless of the output voltage, current or coil resistance. The max output voltage is 9 V, current 50 A so both a 0.2 ? & a 0.4 ? resistance would still need 206 W from the battery at 200 W. Ultra low res takes it over the output current limit (50 A) A 0.05 ? resistance at 200 W would need 63.25 A for 200 W which is over the current limit, but only need 3.16 V well within the voltage limit. Higher res takes it over the output voltage limit (9 V) A 0.5 ? resistance would need 10 V for 200 W which is over the max voltage limit, but would only need 20 A well within the current limit.

I do dual coils with SV NiFe30, 9 wraps of 0.4 mm, 2mm ID they are 0.07 ?, I even do dual with the same size Ni200 (0.03 ?)

No it is set in the hardware, they had to increase the size of the PCB to get 2 A charging for the VaporShark.

Well said poitee

StealthVape's NiFe30 is very good, still quite low res, but IMO the next best wire to Ni200. I dry-burn then quench all these wires by using a little higher TCR, low watts and setting the temp to 600 F, if you do this it is entirely at your own risk and you should do your own research, but this is what I do: For Ni200 use 0.008 as a TCR For NiFe30 (SV) I use Ni200 wire type For Ti I use I use NiFe wire type I reckon all these keep me below 900 F, start at 550 F in low lighting so you can see if it starts to glow more than very dark red.

There is more detail on this on the Mod Res thread /topic/65594-topic/ particularly posts #8, #11, #14 & #25 John on using mod res just to get more power post #25

I have edited one post and deleted several, it is a shame as everybody tried to help the OP.

It is not showing the battery icon either, check it is not set to power supply as battery type in Escribe, I don't if a blow fuse would cause that.

From the UK Warehouse a standard 25-50C nano-tech that a lot of people use is £7.91 and this battery is 70% more @ £13.45, you can use Max Recharges setting to double the life of the standard LiPo and that would probably be about the same capacity as this battery running at 4.2 V.

Good point, they would probably be more like 1170 mAh at 4.2 V (-10%) which should double their working life, but I think these batteries that push the limits of the chemistry are generally shorter lived anyway.

IMO there are no pros for this application, they are bigger, you wont use the extra voltage and would probably have a shorter working life, though not sure on the last point. They should work fine though if you really want to use one.

Not sure, the 133 W power limit is well known, but the 6 V output limit is not and will lower the max resistance level VxV/P, it should not effect the low res limit as that comes from the max current limit. Maybe Higher coil resistances limit the max power with two cells or Max resistance is lower for two battery cell operation The DNA 200 is a step down converter designed to run from 3 Li cells is series and is limited to a max output voltage of 9 V. After multiple user requests in this forum Evolv released firmware that allowed it to operate from 2 series cells at reduced power (133 W). The max output voltage has also changed to 6 V for 2 series cell implementations. So you need a resistance between 0.0532 ohm and 0.27 ohm for 133 W (max power) in this mode. The max resistance can be calculated by voltages squared divided by power, the max voltage is 6 V so 36/power will give you your max res a any supported power level. No doubt my pros could be improved, not my strong suit.

If Evolv change the firmware to do this then sure as eggs are eggs people will us it regardless, so if I were Evolv I wouldn't because they have given manufactures a written spec and this would exceed the limits in that. Evolv have always prioritised safety and reliability, having voltage and current limits in the firmware are part of that as it is in modern cars that limit your engine revs in the ECU for the same reasons. We knew it was a 200 W device when we bought it. Anyway the request is here for Evolv to see and comment if they wish.

This may be worth including /topic/67167-topic/?do=findComment&comment=904624 about 6 V output limit with 2 cell operation.

I have moved the posts about increasing the max power to http://evolvapor.forumchitchat.com/post?id=8052007

This has not been confirmed, but I am 99% sure it it your issue: the DNA 200 is a step down converter designed to run from 3 Li cells is series and is limited to a max output voltage of 9 V. After multiple user requests in this forum Evolv released firmware that allowed it to operate from 2 series cells at reduced power (133 W). It is the input voltage that has changed and it does not step up voltage the max output voltage has also changed to 6 V for 2 series cell implementations. So you need a resistance between 0.0532 ohm and 0.27 ohm for 133 W (max power) in this mode. You want 75 W in 2 cell the max res = 0.48 ohm, in 3 cell = 1.08 ohm V squared over power

Never had a DNA go wrong and I have had over a dozen, but random chance has no memory EG flip a coin and you get heads 5 times in a row the chance of getting heads is still 50% on the next throw. 4 fails in a row could just be a random thing like coincidence it can happen EG meeting someone you know thousands of miles from home.