DNA 250 hard cut off voltage

Discussion in 'VV/VW APV Discussion' started by jakeycrx, Jun 3, 2017.

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  1. jakeycrx

    jakeycrx Full Member

    Jun 2, 2017
    This is an issue which I'm hoping @Mooch will be able to chime in on but I'm interested in other people's opinions as well.

    The hard cut off voltage of the DNA 250 is set at 2.9 volts and cannot be adjusted. I find this frustrating as it starts cutting out for low battery when the battery is still at 20%. I ran the battery analyser on my 30Q's so the battery meter should be accurate. The batteries are only a month old as well.

    The load voltage is 2.9 volts when it starts to cut out but the resting voltage is still at 3.4 volts so there is still a bit of life left. If only I could lower the hard cut off then it would compensate for the voltage sag and let me get more vaping time from my batteries.

    Do people think it would be a good idea to allow the hard cut off to be lower?
     
    conanthewarrior likes this.
  2. Mooch

    Mooch Electron Wrangler Verified Member ECF Veteran

    Supporting member
    May 13, 2015

    Perhaps. But it would be badly abused by some and risk damaging cells if it could be lowered. 2.9V under load with a 3.4V recovery is a lot of current being pulled.

    It's better to either lower your wattage to a level better suited to the 30Q's abilities or use a battery like the VTC5A that has a lot less voltage sag.

    Just a thought...did you run the analyzer at the power level you typically use?
     
  3. jakeycrx

    jakeycrx Full Member

    Jun 2, 2017
    I'm running TC mode with a 150 watt ramp up so it is fairly high on the wattage.

    I was considering VTC5A's but after comparing your 30 amp pulse charts for 30Q and VTC5A the 30Q appears to have slightly more run time before it hits 2.9 volts under load.

    I ran the battery analyser at 100 watts. I wanted to go higher but my resistor bank is 0.53 ohms and the mod cuts out for check battery if you go too high even with fully charged batteries. I think it's something to do with the output voltage limit on the DNA.

    My resistor bank can take the power. 2 x 750 watt 1 ohm resistors wired with 12 AWG :D

    [​IMG]
     
    conanthewarrior and Mooch like this.
  4. conanthewarrior

    conanthewarrior Senior Member ECF Veteran

    Feb 2, 2014
    Essex, England.
    I don't own any DNA250's myself, but do have 4 DNA200's in the collection, and it is also something I didn't like, not being able to lower the cut off voltage below the hard limit.

    I tend to vape at around 40W and 240C, with around a 70W preheat. TC kicks in fairly quickly and power is reduced, so I am not stressing my batteries much at even at say 2.75V per cell- my 25R's or 30Q's are more than enough for this.

    EDIT: 8.43A before efficiency at 2.75V per cell cut off in triple config before efficiency, say 9.4A at around 90% efficiency.

    As @Mooch mentioned though, a lot of people would likely change this abusing or not fully understanding the implications, but am I mistaken in thinking that the input current limit in Escribe would stop things getting too bad? And also the fuse would blow on the input side as well if someone did set it too low, and using a fairly high wattage if somehow the limit set by escribe was bypassed?
     
  5. jcoopercam

    jcoopercam Senior Member ECF Veteran

    Dec 29, 2009
    Florida
    I'm using a Triade DNA 250 with Sony VTC6 batteries, which I can run-down well-past the 20% mark. Well, I assume I am... There was nearly nothing left on the battery indicator when I removed them for charging. I'm running a Goon w/Trinity glass @ .5 Ohm's. The Trinity glass results in the best flavor ever! Sorry... Couldn't help but rave. :)
     
  6. MadTemp

    MadTemp Senior Member ECF Veteran

    Dec 30, 2015
    So vtc4 or lg hg2? The amp output is simple in dna200, vtc4 does the job. How is the amp converter on the 250?
     

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