Trying to understand DNA250 55amp max output

[Vesh]

Hi there!
Finally received my first dna device, second in total, had a 40 for a while.
I love the way they just instantly fire.. zero lag!
FYI, i got the think vape finder 250, and sometimes the plus and minus buttons get stuck and keep going till i press them a couple times and they pop out. I am most unimpressed with that part, so just a heads up in case it's an across the board fault (i dunno). It doesn't happen *that* often and thankfully the fire button doesn't seem to do it, so that's something.

Anyway, i read the specs on the dna 250 amps. Evolv say it's 55 amps output with a 60 peak in some situations.

What they don't explain is if it is split amongst the cells (this is a 3x18650 device).

If the maximum output possible under any circumstance is 60 amps *divided* per battery, that means 20 amp max per battery, which means even stuff like 30Q's are totally safe in there, as Mooch rates them as 20A continuous.

If it's per battery, well obviously that is way over what any battery on earth can reach so anything really is not safe, but in that case i'd go for HB6 1500mah LG pinks which are 35A continuous.

Any ideas? I can't see how it would make sense that the amp maximum is not divided by the batteries, but i thought i better check. TIA!

 

[Vesh]

By the way, I used Mooch's regulated mod calculator.. the DNA 250 minimum voltage is 9 volts, so 3 volts per battery..
You divide the 250 / 3 = 83.3
And then the 83.3 / 3 (for the 3 volts).
= 27.8

So by my calculations, no matter what the answer to above is, the absolute maximum a dna 250 can draw from each cell is 27.8 amps... which would mean vtc5a's are safe at it at any setting it can do, ya?

If mooch drops in would be marvellous!

 

[Flavored]

55 amps is on the output, not the input. Your second post is the correct math for "conservation of watts" from input to output with the exception the chip isn't 100% efficient, so fudge it a little in the conservative direction.

 

[Vesh]

Huh? I clearly said 55 amps output, twice.
I used the minimum VOLTS for the input.

I am asking if it splits the max 55 amp (60 peak) between the three cells, which would mean 20 amp cells are ok.

If that's the case, the other math doesn't really matter.. if it's max 60 amps output split between cells, that means it won't do higher wattages as the cell voltage lowers anyway.. the 60 amps means 20 amps max per battery, which means the DNA will only probably do 250 on absolutely freshly charged batts. It means the chip is very safe above anything, and any battery will do, cause any 18650 these days does 20 amps. ( i mean non protected 2500 mah and under, most of them are 20 amp continuous batteries, except the 30Q, which is 20 amp with 3000mah capacity)

 

[mongo74]

Are you planning on running that at 250w? You would need a trio of 25a MINIMUM (and you're still going over their CDA) and preferably three 30a batteries. IIRC, regulated mods, regardless of chip, draw amps from each battery according to their cut off voltage. The mod would be pulling 28a (27.7) from EACH BATTERY @ 250w. The one good thing about DNA chips is their efficiency. (aside from the obvious like Escribe and excellent TC)

Guessing after a quick drop in voltage, firing again at 250w would give you a WEAK BATTERY error.

 

[Topwater Elvis]

Output = from chip to delivery device. The cells never see this drain.
Input = from batteries to chip. This is the draw from the batteries to the 'chip'.

The dna 250 has a 28a maximum input current, meaning the chip, regulator, magic gizmo board (whatever you want to call it) will never draw more than 28a from the batteries.

The 28a is shared by the cells.

 

[Vesh]

Are you planning on running that at 250w? You would need a trio of 25a MINIMUM (and you're still going over their CDA) and preferably three 30a batteries. IIRC, regulated mods, regardless of chip, draw amps from each battery according to their cut off voltage. The mod would be pulling 28a (27.7) from EACH BATTERY @ 250w. The one good thing about DNA chips is their efficiency. (aside from the obvious like Escribe and excellent TC)

Guessing after a quick drop in voltage, firing again at 250w would give you a WEAK BATTERY error.

sure i might try it with one of those new fancy coils that say they can do 300w lol. Why not?
Right, 27.7 is the maximum amps it could ever draw, according to the regulated mod calculation (9 volts cutoff = 3 per battery = 250/3 then 83.3/3 as said in first post). But we should add 10% to be safe, so let's say 30 amps.. So VTC4's can pulse to that safely, so in any case, i have batteries where i could *try* 250 safely.

But IF the max output is 60 amps total (evolv say 55 with 60 peak), then it could never hit 27.7 amps per battery anyway.. this is why i am asking if the 60 amp peak output is designed to be split 3 ways amongst each battery.. I am pretty sure in a series mod this is how it would work, but i just wanted someone who was 100% sure to confirm. If it's so, and no matter what wattage setting it maxes at 60 amps /3, then 20 amp batteries are fine. Make sense?

 

[Topwater Elvis]

You are confused about how it works.

Input = from the batteries to the chip. DNA 250 = 28a max input current.
Output = from the chip to delivery device, the batteries never see this load.

 

[Vesh]

Output = from chip to delivery device. The cells never see this drain.
Input = from batteries to chip. This is the draw from the batteries to the 'chip'.

The dna 250 has a 28a maximum input current, meaning the chip, regulator, magic gizmo board (whatever you want to call it) will never draw more than 28a from the batteries.

The 28a is shared by the cells.

sorry that's not how mooch describes it and i trust him implicitly. He talks about watts settings and voltage of battery when you fire, and series mods..you divide the watts by the battery voltage.. in this case you divide your watts by 3, then that watts figure by the individual cell's voltage. And that's how I did my calculations. 28 amps shared by three batteries, you are saying the DNA250 will only ask 9.33 amps of each battery max, and there's no way I buy that. If you mean 28 amps per cell, that makes sense, that's what i was at with my 27.7 figure already anyway.

 

[Flavored]

Huh? I clearly said 55 amps output, twice.
I used the minimum VOLTS for the input.

I am asking if it splits the max 55 amp (60 peak) between the three cells, which would mean 20 amp cells are ok.

If that's the case, the other math doesn't really matter.. if it's max 60 amps output split between cells, that means it won't do higher wattages as the cell voltage lowers anyway.. the 60 amps means 20 amps max per battery, which means the DNA will only probably do 250 on absolutely freshly charged batts. It means the chip is very safe above anything, and any battery will do, cause any 18650 these days does 20 amps. ( i mean non protected 2500 mah and under, most of them are 20 amp continuous batteries, except the 30Q, which is 20 amp with 3000mah capacity)

Yes, I know you did, but you're confusing the current output with battery draw/input. The way you did it in post 2 is the correct way to calculate the battery draw: Use the watts output and battery voltage to calculate battery current.

 

[KenD]

sorry that's not how mooch describes it and i trust him implicitly. He talks about watts settings and voltage of battery when you fire, and series mods..you divide the watts by the battery voltage.. in this case you divide your watts by 3, then that watts figure by the individual cell's voltage. And that's how I did my calculations. 28 amps shared by three batteries, you are saying the DNA250 will only ask 9.33 amps of each battery max, and there's no way I buy that. If you mean 28 amps per cell, that makes sense, that's what i was at with my 27.7 figure already anyway.

28 amps per cell. And the input and output amps are totally separated from each other. As Topwater Elvis says, the batteries never see the output amps.

Sent from my K6000 Pro using Tapatalk

 

[bwh79]

The 28a is shared by the cells.

...shared as in "felt by each" or shared as in "split evenly among them"? They're wired in series and so the full 28 amps is "felt" by each one, right? So you'd wanna have 30A batteries in there, ideally.

 

[APathos]

So what you've read from Mooch I'm sure is correct, but as others have said, I think your missing that the setup is a two step process:
battery(ies) --(I=P/V)--> regulated mod with dc-dc converter (buck/boost) --(I=V/R and P=V^2/R)--> atty
Ignoring the chip/mod/atty efficiency. If your looking at the output power graph of the datasheet, you can do the calculations, and see the low ohm end is limited by the chips max 55A, and the high ohm end is limited by the chips max 9.3V. Those are output maxes of the chip.

i.e. delivering 250W at 0.05ohms requires 70A, so no, chip cannot do that. delivering 250W at 1ohm requires 15.8V. so no again, chip cannot do that.

 

[Topwater Elvis]

---> Calculating battery current draw for a regulated mod | E-Cigarette Forum

Notice he states series / parallel makes no difference using the equation he describes.

 

[Vesh]

28 amps per cell. And the input and output amps are totally separated from each other. As Topwater Elvis says, the batteries never see the output amps.

Sent from my K6000 Pro using Tapatalk

how can it be 28 amps per cell when the max amps is 60 at peak? are you telling me the input amps exceeds the output amps then?

otherwise i am totally lost.

I just wanted to say, i greatly appreciate all the replies and attempt to help me in this situation, i really do, but I just don't understand it properly.

maybe i will try in a laymans way: should 25R's be safe in it or you think that's too risky? Would a 25R blow up if it pulsed to 28? I mean that would be really in the rarest situation as my normal vaping is tootling, so it might be a rare pulse of cloud chasing.

I have three vtc5a's in it, but i'd rather have them in my 100 watt single battery mods where i feel they are much safer than a 25R.

I've also ordered some HB6's but they are only 1500 mah, and who even knows if they are genuine.

 

[Vesh]

So what you've read from Mooch I'm sure is correct, but as others have said, I think your missing that the setup is a two step process:
battery(ies) --(I=P/V)--> regulated mod with dc-dc converter (buck/boost) --(I=V/R and P=V^2/R)--> atty
Ignoring the chip/mod/atty efficiency. If your looking at the output power graph of the datasheet, you can do the calculations, and see the low ohm end is limited by the chips max 55A, and the high ohm end is limited by the chips max 9.3V. Those are output maxes of the chip.

i.e. delivering 250W at 0.05ohms requires 70A, so no, chip cannot do that. delivering 250W at 1ohm requires 15.8V. so no again, chip cannot do that.

Fantastic.. I DO get this.. I think that's what i said above.. if that's the maximum amps, it simply won't ba able to do certain wattages at certain resistances.. I get that...

But it still goes back to my question, if the max is 60 amps, doesn't that mean that no single battery could EVER be asked for more than 20 amps?

 

[Topwater Elvis]

Output amps (the 55-60a you keep talking about) is produced & controlled by the chip/boost/buck circuit/regulator/ magic gizmo board.
Output = current produced by chip to power delivery device.

Input = current drawn from batteries to power chip. The maximum input current
for a DNA 250 is 28a.

The DNA 250 has a 30a fuse on the input side to protect batteries in case of short/malfunction of the chip/board.
It will never draw more than 28a from the batteries, if it demands 30a+ the fuse will blow.

Read the spec sheet.

 

[Vesh]

Why be condescending? I have read the spec sheet multiple times.. did you read the part where I said I didn't understand how this all works, and am simply trying to? Your explanation helped a lot until the last line.

The spec sheet just says input current is 28 amps, but it does not say if that is total or split amongst the batteries.

And if it's total, which means 9.3 amp per battery, that changes mooch's entire conversion calculator, as suddenly,it doesn't really matter if what's being asked of the batteries only happens at input (which i didn't know until this topic, i just presumed it would happen at output when you pressed the button).

Where does the spec sheet say, in clear terms, that the dna250 can ask up to 28 amps per battery? and why doesn't it make that more clear, or say "load split" or "maximum per battery".. it also says typical is 9. I presume that's just what they consider to be average use for most people.

So if it's 28 per battery, that means it can take up to 84 input, but maximum it will output by bucking is 60..

if it means 28 split, that's all it asks for the batteries is up to 9.33 amps each, then it's impressive chip can output up to 60

if the latter, it means i can safely use even samsung 30Q's in there, for maximum run time.

Not one person has recommended which batteries are safe in the dna 250 yet.. which was kinda the whole point of my topic.. and yes i've read the specs 100 times

 

[Vesh]

APathos, how can the chip require certain apms at certain ohms, when Mooch repeats over and over that resistance has not a single thing to do with amps drawn in a regulated mod?

It's simply about watts chosen and battery voltage with regulated devices - that's it.

The limiting factor is voltage peak and low which is 0.5 - 9.3.. but at 0.05 ohms per your example, the voltage would be 3.53 at 250 watts.. so the DNA 250 can in fact do 250 watts at 0.05 ohms as far as OUTPUT voltage is concerned. The problem here would be it's max amp specs..

If it's 60 amps total output, then no it can't do 250 watts at 0.05 ohms, regardless of it being within the voltage specs of the device..
Cause that would be 80 amps which is far above it's 60 amp peak output.
Which goes back to my question on how the load is split..
and in fact means, using mooch's conversion, that the dna250 could not do 250 watts at ANY resistance, unless the batteries are fully charged above 4 volts.. so it must have a very small window it can do the full output at.

AGAIN, this is using Mooch's conversion. 250 watts/3 and then the result divided by the single cell voltage..

or you can just do the total watts divided by the total cells voltage combined.. same result...

I am starting to get the impression here that not many really know much more than I do.. and because it's about my safety, I only want answers where someone is 100% certain if that's ok!

If we can get someone who is absolutely certain about this:

- regardless of input or output or where it does it's magic.. in layman's terms, what is the maximum amps the DNA 250 could EVER ask of *each* battery cell individually?

If it is definitely 28 AMPS per cell, then no way are 30Q's or 25R's safe.. i would have to go with my vtc5a's or aspire 1800's, to be completely safe.

if it's 9.3 amps per cell on input, then it's fine, i can use any battery I have. I have two totally conflicting answers on this, one says 28 per cell, one says it's 28 split among the three.. so i really need an answer of someone who is sure, as evolv are not emailing me back..
Don't think i don't appreciate this, but what i would also appreciate is tolerance when someone does not understand mod circuitry..

I am a computer and music programming whiz, and i have to deal with teaching people all the time... i KNOW it's frustrating, but i promise i will always help ANYONE out when it's about something I am sure of (like macs or digital audio workstations). Cheers

 

[Bunnykiller]

obviously its split between batteries... why would DNA create a board that would intentionally draw 60 amps from each battery when there is no available battery on the market that can supply the current?

kinda like creating a car to do 500mph when there are no roads capable of handling the car