xs2man
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Post by xs2man on Aug 19, 2014 19:27:22 GMT
Your batteries will be fine. Even pushing 0.5 ohm coils at 30 watts (the limits of a REAL DNA chip) wont go over 10A. Evolv spec gives max input current of 12 A, would give that some head room on a clone. Yeah, that's what they say for a safety margin. 30 Watts at 0.5 Ohms is 7.75A though, so they are giving themselves nearly 5A headroom. I wouldn't necessarily trust a clone DNA to be honest, you have no REAL idea what is going on to be honest. But unless it's pumping out 50 watts instead of the 30 it's meant to be doing, it wont break 10A at 0.5 Ohms. According to physics anyway.
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VapingBad
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Post by VapingBad on Aug 19, 2014 20:33:11 GMT
xs2man you are broadly right, but they are not 100 % efficient and will fire 30 W with the battery as low as 3.45 V in my experience, the resistance is not needed to calculate input current. They can also fire over 30 W as they are build with predicted output losses so a mod with very low output loss will give over 30 W. So if we say want 32 W + 7% (guess) due to inefficiency would be more like 34.4 W from a 3.44 V battery would be 10 A even without accounting for the extra amps needed due to voltage drop on the battery, I feel these figures are realistic, but not exact. I think the margin is more so customers are not disappointed with the battery life or pushing their batteries to their limits. The DNA will take care of all this for you and if your battery is struggling it wont fire.
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VapingBad
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Post by VapingBad on Aug 19, 2014 21:18:27 GMT
Thanks, after watching the pBasardo videos at Evolv where they mention one of the design goals of the DNA is to look after you I think the SX have gone the other way and try and extract as much run time as they can and would probably reduce your battery life span. I don't know by how much though. I think that makes it even more important to have a very high current battery in the SX and the one I trust the most Sony VTC. Does do a few drags where it auto drops to 10watts first, maybe with battery with more sag issues it would do this more? I'd or thought so anyhow. Does make me wonder about these upcoming SX 100watts devices that will use two 18650 batteries. Afterall, guess they will run in parallel, so need to be same volts etc, wonder what safety features on chip there will be for this. I will know first hand soon as I just ordered an IPV2 from Liberality Flights (last one) cause lardarse posted a 35% code and I got it £47 inc delivery
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boyofford
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Post by boyofford on Aug 19, 2014 21:21:56 GMT
Does do a few drags where it auto drops to 10watts first, maybe with battery with more sag issues it would do this more? I'd or thought so anyhow. Does make me wonder about these upcoming SX 100watts devices that will use two 18650 batteries. Afterall, guess they will run in parallel, so need to be same volts etc, wonder what safety features on chip there will be for this. I will know first hand soon as I just ordered an IPV2 from Liberality Flights (last one) cause lardarse posted a 35% code and I got it £47 inc delivery couldn't resist any longer? Not used out else since got it, even with its flaws. And that price is ridiculous! I'd get a spare if I wasn't waiting to see what was happening with 100w devices.
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VapingBad
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Post by VapingBad on Aug 19, 2014 21:27:36 GMT
I will know first hand soon as I just ordered an IPV2 from Liberality Flights (last one) cause lardarse posted a 35% code and I got it £47 inc delivery couldn't resist any longer? Not used out else since got it, even with its flaws. I have 2 DNA30s, but it was the last one, that price wont come up often and I didn't get myself a 2 year vaperversary present.
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Post by VapingBad on Aug 19, 2014 21:35:49 GMT
Just to add to the DNA battery info for a Panasonic CGR18659CH 10 A vaping at 10 W the DNA rejects it at 3.435 V, at 25 W this would be 3.625 V. This is because it monitors how well the battery is copping with the load and not just the voltage.
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xs2man
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Post by xs2man on Aug 19, 2014 21:37:43 GMT
xs2man you are broadly right, but they are not 100 % efficient and will fire 30 W with the battery as low as 3.45 V in my experience, the resistance is not needed to calculate input current. They can also fire over 30 W as they are build with predicted output losses so a mod with very low output loss will give over 30 W. So if we say want 32 W + 7% (guess) due to inefficiency would be more like 34.4 W from a 3.44 V battery would be 10 A even without accounting for the extra amps needed due to voltage drop on the battery, I feel these figures are realistic, but not exact. I think the margin is more so customers are not disappointed with the battery life or pushing their batteries to their limits. The DNA will take care of all this for you and if your battery is struggling it wont fire. Fair enough. But the DNA limits its circuits to 30w. So you are guestimating an error of almost 20% on power, on a battery that is pretty much gone? Just to get to the stated amp limit on a battery (that will inevitably have some headroom associated also, assuming it is from a reputable source). And even assuming all this actually happens, there is safety circuitry in the device itself, as you say, that will stop it from firing. It's all a bit theoretical by this point, making many assumptions on the inconsistency and inherent error associated by a generally accurate regarded device. I have had no issues firing 30 watts across my 0.5 ohm dripper, running Panasonic CGR's. Anyway, all this is at the extreme end of the GENUINE devices specs. Somewhere the OP has already said he wouldn't be near. All I was saying was that his batteries will be fine for his intended use of the genuine device. I also said the specs of the clone would be essentially unknown, as they will inevitably just copy the spec sheet of the genuine DNA regardless of actual performance. And I for one wouldn't trust a clone chip at the limits of operation. That said, the OP has said they are not at the limits of operation, so maybe a clone would work fine for them?
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VapingBad
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Post by VapingBad on Aug 19, 2014 22:13:52 GMT
"So you are guestimating an error of almost 20% on power, on a battery that is pretty much gone?" xs2man how do you get 20% ??? These are not wild guesses, but realistic figures. I added 2 W (6.67 % which is a guess) to the output as Brandon from Evolv has said they are over the power in the spec so they can still provide 30 W to the atty on devices with a higher resistance output path and you can easily get over 30 W out of them in a good device. I guesses the electrical efficiency to be the same as the SX which is 93%, which seems realistic to me. I don't think I made any mistakes with the maths so can't see my figures will be of by much more than a percent or two. The resistance of the atty is irrelevant for these figures as 30 W powering 0.5 ohm is the same as 30 W powering 1 ohm, the board changes the output voltage, but still needs 30 W + losses in efficiency from the battery (it would make a tiny diff, as the 1 ohm coil would require 1.65 V more voltage than the 0.5 ohm one and that would generate greater loss, but we would need more data than is available to guess this). I didn't say the battery had almost gone, don't understand where that came from, unless you mean just before the DNA rejects it as needing to be recharged. I reckon the most of DNA users with swappable 18650 mods will still be vaping (safely) until the need to change the battery, I just removes a CGR at 3.435 V. I know the OP is vaping around 10 W and said the Efests should be OK, but I post the info about the general use of the device as others will read this who vape differently and it will help them. Not trying to start an argument and think you have made some good general points xs2man.
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xs2man
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Post by xs2man on Aug 19, 2014 22:24:16 GMT
Ok. 15% then, sorry. (4.4/30) * 100 = 14.6666% (You did end up with 34.4 watts). The device doesn't actually say it goes to 32 watts, so that is already introducing error there, and you are then compounding the error by adding the further 7%. So you are effectively saying the DNA30 can be off by nearly 15%?
3.4xx volts I would say is at the bottom end of battery life. Most of my regulated devices stop at 3.6v, I generally swap out before this point if I can, so 3.4 volts, to me at least, is as good as gone (as in depleted).
I'm not trying to start an argument either, just pointing it out as I see it.
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VapingBad
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Post by VapingBad on Aug 19, 2014 23:12:31 GMT
Cool were in a sprite of friendly discussion xs2man. The 34.4 W is what the board would need from the battery to output 32 W with 93 % efficiency and not 34.4 W on the output. For 30 W output it would need 32.1 W from the battery. The 7 % is not an error it is the loss due to inefficiency (mainly heat produced) and normal in any power transforming circuit, the SX chips quote 93 % efficiency which is good and a realistic figure as I don't have one for the DNA. So for each 10 W is taken from the battery only 9.3 W will get to the output of the board. There is no error on the output, it just needs more power to run and light up the screen. 3.4xx V is what my real world DNA runs down to depending on the battery and output power it varies a lot, but varies very consistently with load and battery spec, its not like most VW devices. This is one of the main benefits of this type of device getting a consistent vape until your battery needs changing. Yes it is almost empty (at low watts), but it is still being used safely by the DNA and it is the point that the battery will have the max current demand which is why I used it as we were talking about the suitable current rating of batteries. Plus what I did not try to guess is at this high current and low voltage the battery voltage will sag the most actually making the volts go down and the current go up. Evolv deliberately overpowered the board as other people design & build the mods which they have very little control over and they didn't want people shouting that my DNA only goes up to 28 W, I think that's a good thing as everyone adjusts to tastes anyway. Think of it like this if you buy a 100 ml bottle of juice and get 95 ml you would be disappointed, but if you got 105 ml you probably wouldn't. I maybe wrong with 32 W, it maybe 31 or 33, 32 W seemed reasonable. Here are the figures to help explain: My figures were to get 32 W output you need 32 W/93 x 100 = 34.41 W from the battery and just before you need to change the battery (if its a good VTC) its voltage is around 3.455 V (I cheated and lowered to 3.441 V to make the answer an whole number). To get 34.41 W from a 3.441 V battery requires 10 A not allowing for the extra that would be caused by battery sag. If you forget the extra 2 W and stick to the 30 W spec it would be 9.37 A not allowing for the extra that would be caused by battery sag, but your max of 7.75 A would be much too low, its at least 10 A IMO.
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xs2man
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Post by xs2man on Aug 20, 2014 8:09:45 GMT
Even so, it's still within battery specs, which will have headroom too. So still, in theory, safe to use at the extremes of operation.
I'm not saying don't use VTC's. I'm just saying the likes of CGR's can be used safely with the DNA 30. So there is no reason to immediately budget for new batteries. Of course, VTC's would make a great purchase the next time they need batteries. I know I'm unlikely to get more CGR's in the future, as I'll only be buying VTC's (or Torchys 30A batteries).
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VapingBad
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Post by VapingBad on Aug 20, 2014 9:11:47 GMT
Even so, it's still within battery specs, which will have headroom too. So still, in theory, safe to use at the extremes of operation. I'm not saying don't use VTC's. I'm just saying the likes of CGR's can be used safely with the DNA 30. So there is no reason to immediately budget for new batteries. Of course, VTC's would make a great purchase the next time they need batteries. I know I'm unlikely to get more CGR's in the future, as I'll only be buying VTC's (or Torchys 30A batteries). IIRC I did say all that earlier, but 7.75 A was to low, I imagine the real max input current is 11.x A rounded up to 12 A and don't believe that it is good to vape close to the limits of your battery mainly for the life of your battery, but also safety. The reason I believe the VTCs (IIRC Torchys 30 A are VTCs) are recommended are they are the only very good battery substantially over 10 A that is widely available, 20 A would be fine.
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