Soft cell cutoff with 25R's.

[conanthewarrior]

Hi everyone, I hope you are all OK.

Today I got my first DNA75 device, and notice the standard setting in Escribe for soft cell cut off is 2.75V.

According to the 25R data sheet, its end voltage is 2.5V, so am I correct in thinking the 2.75V soft cell cutoff point will be fine?
I notice on a 350J clone that near cutoff, batteries do sag under 3V, sometime to 2.8V or even slightly below if I am using a 3000MAH cell.

Thanks for your help, Conan.

 

[martnargh]

im no battery expert but i think that batteries should not be run so low. i could be wrong though.
i usually run them to 3.7 tops.

Sent from my SM-N920T using Tapatalk

 

[conanthewarrior]

im no battery expert but i think that batteries should not be run so low. i could be wrong though.
i usually run them to 3.7 tops.

Sent from my SM-N920T using Tapatalk

I am not too sure as the specs for the 25R do state 2.5V, and I know we don't use the full charge cycle of our batteries so am hoping someone knows a definite answer.
The mod come pre set up by Daniel from DJLSB vapes, so I am thinking it is OK?

I am pretty certain it is OK, just would like clarification. 3.7V is quite a high point to pull your batteries, do you mainly use mechs or do you pull this high to prolong the life of you batteries?

 

[nightshard]

Mooch was discussing this subject in this video, have a look:

 

[conanthewarrior]

Mooch was discussing this subject in this video, have a look:

Thanks , I will have a watch now.

 

[nightshard]

Quite a long vid and discusses a lot of other thing too, but very informative, ty @Mooch

 

[conanthewarrior]

Quite a long vid and discusses a lot of other thing too, but very informative, ty @Mooch

It is a rather long video-I will have to watch it later as it seems like it will be a good watch.

For now I will leave the setting as it is, as mooch tests the 25R down to 2.5V as stated on the data sheet, and the mod is pre set up to work out of the box. When I have time tonight I will watch the video, and raise the soft cutoff if needed.

 

[nightshard]

In short the 2.5V is the bare minimum and refers to the idle and not under sag state.
Still it doesn't mean that you should actually reach it so 2.7-2.8 should be fine I guess.
Dropping lower then 2.5 to around 2.2 is really bad for the battery and even dangerous.

 

[Angrygod50]

It's how low the battery can get under load. Evolve recommends 3.09 volts. ↑↑↑ That s good video to watch I'd also suggest looking at the Evolve forum.

 

[conanthewarrior]

It's how low the battery can get under load. Evolve recommends 3.09 volts. ↑↑↑ That s good video to watch I'd also suggest looking at the Evolve forum.

Yes I realised it is under load-does Evolv suggest 3.09 for the soft cell cutoff (Under load) or for the mod to not fire?
EDIT: I will ask at the Evolv forum to make sure 100% just in case I am wrong keeping the soft cell cutoff at 2.75V.

I just expected as the device is pre set up, and mentions in the manual the cut off voltage, and recommends batteries to use for this voltage, it would be OK.

 

[conanthewarrior]

In short the 2.5V is the bare minimum and refers to the idle and not under sag state.
Still it doesn't mean that you should actually reach it so 2.7-2.8 should be fine I guess.
Dropping lower then 2.5 to around 2.2 is really bad for the battery and even dangerous.

I thought so, and seeing as it is under load, the 2.75V setting, I will keep it as is.
Thanks for your help.

 

[Angrygod50]

Yes I realised it is under load-does Evolv suggest 3.09 for the soft cell cutoff (Under load) or for the mod to not fire?

The mod will still fire but the weak battery message will come on. I never took mine down enough for the mod to shut off.

 

[conanthewarrior]

The mod will still fire but the weak battery message will come on. I never took mine down enough for the mod to shut off.

Oh OK, maybe it will make sense to raise it slightly. I have posted over at the Evolv forums to find out what they recommend.

Thank you for your help, Conan.

 

[conanthewarrior]

OK, looking over at the Evolv forum 2.75 is fine, I will keep it there. Must say I am impressed with the DNA75 so far!

 

[Angrygod50]

OK, looking over at the Evolv forum 2.75 is fine, I will keep it there. Must say I am impressed with the DNA75 so far!

I loved my DNA 75 so much the day I got it I ordered another. The temp control for SS wire is spot on and the new update for the DNA 200 is also spot on.

 

[conanthewarrior]

I loved my DNA 75 so much the day I got it I ordered another. The temp control for SS wire is spot on and the new update for the DNA 200 is also spot on.

I must say, with the DNA200's I own, I was a bit disappointed with SS TC-until I updated to the newest version of Escribe and SP3 for them-now SS 316L is my wire of choice, and I am very happy with the devices.

The DNA 75 even with just half a days use, I know I will hardly use my other mods now for taking out with me, this is a perfect size, and performs fantastically.

Sure, they do cost more than other devices I own, but with the customisation available and the quality of the vape I feel it is well worth it.

 

[HondaDavidson]

While 2.75 is a "safe" value.....In that it won't out and out damage the batts or the mod... A higher cut-off point will improve Both, battery longevity and over-all performance..

This is part of the why most mods automatically cut-off at 3.2 volts or so and most Mech users change batts at 3.5-3.7 volts (if not higher).

 

[SirRichardRear]

@Wingsfan0310 might have an answer for this

 

[Angrygod50]

I have one of the fields showing battery pack voltage and when my meter shows empty the battery shows around 3.4 volts.

 

[Wingsfan0310]

Hi everyone, I hope you are all OK.

Today I got my first DNA75 device, and notice the standard setting in Escribe for soft cell cut off is 2.75V.

According to the 25R data sheet, its end voltage is 2.5V, so am I correct in thinking the 2.75V soft cell cutoff point will be fine?
I notice on a 350J clone that near cutoff, batteries do sag under 3V, sometime to 2.8V or even slightly below if I am using a 3000MAH cell.

Thanks for your help, Conan.

I'm using 25R's in my Lavabox MDNA75 and I have the cutoff set at 2.75v. That's the sag voltage. It will bounce back up higher when not under load. The cells are tested down to 2.5v so setting the sag voltage to 2.75v is no problem.

I set it like that because if I'm out and about I don't want my mod shutting off on me if I still have juice left. If I'm home I can always change the 18650 before it cuts off if you know what I mean.

Cheers,
Steve

 

[conanthewarrior]

I'm using 25R's in my Lavabox MDNA75 and I have the cutoff set at 2.75v. That's the sag voltage. It will bounce back up higher when not under load. The cells are tested down to 2.5v so setting the sag voltage to 2.75v is no problem.

I set it like that because if I'm out and about I don't want my mod shutting off on me if I still have juice left. If I'm home I can always change the 18650 before it cuts off if you know what I mean.

Cheers,
Steve

Thanks mate, I did think it was voltage under load and it would be OK, I just wanted clarification really.

I haven't received the weak battery message myself, and also do not want the mod shutting off on me while I am out and about-I can already tell this is going to get a lot of use as a take out mod, I just feel sorry for all of my other devices lol!
And yes I know what you mean, when I am home I usually pull my batteries before the device will no longer fire-I know I am not damaging my batteries allowing them to do so, but I just like doing it this way when at home the same as you.

 

[conanthewarrior]

While 2.75 is a "safe" value.....In that it won't out and out damage the batts or the mod... A higher cut-off point will improve Both, battery longevity and over-all performance..

This is part of the why most mods automatically cut-off at 3.2 volts or so and most Mech users change batts at 3.5-3.7 volts (if not higher).

The battery is around 3.1-3.2V when it will no longer fire, the soft cell cutoff is voltage under load, not resting voltage.
I just really wanted to make sure it was OK for safety reasons as well as keeping my batteries working for a long time, calculating my amp load correctly I was within safe limits at 2.75V at 40W, 14.4A or 17.11A with 85% efficiency factored in.

I was pretty sure it was fine, but wanted to make sure 100% .

 

[HondaDavidson]

Under load is when I would want to keep volts higher......... it's when there is load or amps being moved that smoke escapes from batteries.

Not saying your not safe.. just pointing out some of the logic being used to justify the cutoff voltage. Is flawed.

Even a cliff is safe .... till you step over.



Sent from my SCH-I605 using Tapatalk

 

[Wingsfan0310]

Under load is when I would want to keep volts higher......... it's when there is load or amps being moved that smoke escapes from batteries.

Not saying your not safe.. just pointing out some of the logic being used to justify the cutoff voltage. Is flawed.

Even a cliff is safe .... till you step over.



Sent from my SCH-I605 using Tapatalk

Hows this logic.
The batteries are tested to be safe down to 2.5v under load by the manufacturer.
Evolv sets the cutoff at 2.75 as the default.
Evolv recommends you set it at 2.75v.
Evolv is known to be a conservative company so they wouldn't set it there and recommend you keep it there if it wasn't safe.

Cheers,
Steve

 

[HondaDavidson]

Do they actually Recommend the 2.75 or state it is safe to go as low as 2.75????

Not arguing safe vs not safe here. But as usuall... I am wondering who safety is being adressed. The user or the seller/manufacturers....... 2.75 might be safe for the mod in a lab under testing conditions. My question Is that same 2.75 really safe for user under real world usage conditions. What batteries were used to establish the limit? Would you trust a purple fest battery with 2.75... assuming all other parameters for safety are met?



Sent from my SCH-I605 using Tapatalk

 

[Wingsfan0310]

Do they actually Recommend the 2.75 or state it is safe to go as low as 2.75????

Not arguing safe vs not safe here. But as usuall... I am wondering who safety is being adressed. The user or the seller/manufacturers....... 2.75 might be safe for the mod in a lab under testing conditions. My question Is that same 2.75 really safe for user under real world usage conditions. What batteries were used to establish the limit? Would you trust a purple fest battery with 2.75... assuming all other parameters for safety are met?



Sent from my SCH-I605 using Tapatalk

You can see it on their forum (Evolv Early Adopters Forum). The chip comes preset from Evolv at a 2.75v cutoff.

As for trusting a Purple Efest at 2.75v? the best way I can answer that is I wouldn't buy an Efest battery period. I only buy Samsung, LG, or Sony when it comes to 18650's.
http://vaping360.com/top-5-18650-batteries-for-vaping/

Cheers,
Steve

 

[conanthewarrior]

Do they actually Recommend the 2.75 or state it is safe to go as low as 2.75????

Not arguing safe vs not safe here. But as usuall... I am wondering who safety is being adressed. The user or the seller/manufacturers....... 2.75 might be safe for the mod in a lab under testing conditions. My question Is that same 2.75 really safe for user under real world usage conditions. What batteries were used to establish the limit? Would you trust a purple fest battery with 2.75... assuming all other parameters for safety are met?



Sent from my SCH-I605 using Tapatalk

I am going by Samsungs own specification for the 25R, or LG's for the HE4 for the 2.5V-as for smoke escaping from the batteries, this would only occur under a very big failure with a massive amount of power being drawn from the battery for this to occur, and really would only happen in a dead short situation or an extremely low resistance (near a dead short) in a mechanical mod.

Thermal runaway can happen, but you do need to abuse your batteries well past specification to cause this.

Always stick to good batteries, a purple Efest is not one I would recommend due to the potential for the cell to be different one week to another under the wrapper.

 

[HondaDavidson]

I'm kinda new to regulated vaping... So I still associate with Mechanical usage. Just using the Efest as an example. Although it IS a battery that MANY people still use. I still have some I bought as a newbie. That I have been using for at least 2 years. But then I rarely vape at above 10amps, so I figured why toss them.. They are perfectly safe for MY application. NOW I do use 25R Batteries Only, In my Pico. Yes I know they are under rated for full power. So I won't use full power, anyway.

Just thinking that a .2ohm col at 70watts is pulling 19amps at 3.7volts (100% eff), That means it's Drawing 26amps at 2.7 volts. Which is fine if you have 30amps or more worth of batteries.

Do Regulated mods limit amps DRAWN to that of the batteries rating?
Will it ONLY pull a max of 5 amps from a 5 amp battery? or are those warnings to use batteries of at least x amp rating, There because the mod can and will pull that many amps before limiting itself?

I'm just thinking the voltage cutoff should be based on the amp limit of the batteries in use, RATHER that the mods SELF protection limitations.

 

[conanthewarrior]

I'm kinda new to regulated vaping... So I still associate with Mechanical usage. Just using the Efest as an example. Although it IS a battery that MANY people still use. I still have some I bought as a newbie. That I have been using for at least 2 years. But then I rarely vape at above 10amps, so I figured why toss them.. They are perfectly safe for MY application. NOW I do use 25R Batteries Only, In my Pico. Yes I know they are under rated for full power. So I won't use full power, anyway.

Just thinking that a .2ohm col at 70watts is pulling 19amps at 3.7volts (100% eff), That means it's Drawing 26amps at 2.7 volts. Which is fine if you have 30amps or more worth of batteries.

Do Regulated mods limit amps DRAWN to that of the batteries rating?
Will it ONLY pull a max of 5 amps from a 5 amp battery? or are those warnings to use batteries of at least x amp rating, There because the mod can and will pull that many amps before limiting itself?

I'm just thinking the voltage cutoff should be based on the amp limit of the batteries in use, RATHER that the mods SELF protection limitations.

In a way, yes they will due to the sag that occurs with cells that are very underrated for the application. I wouldn't advise using a cell that is not suitable though.

Also, your mod will be pulling 20.27A @ 75W at 100% efficiency at 3.7V, the resistance does not affect amp load in a regulated device, although I understand this is an easy point of confusion, especially if you are coming from the world of mechanical mods.

The highest I would use the DNA75 is 50W, and at 2.75V that would be 18.18A before efficiency comes into play.

If you are using a good battery such as the 25R or HE4 though, that will be fine with samsungs own pulse ratings they publish on the data sheet. In general, you should go by a batteries CDR, but the 25R is a fantastic cell for handling higher amp loads in pulse situations.

Yes, unfortunately many people do use purple Efests-you mention you use them at 10A so they are OK, but some of their cells were only good for SIX amps and were rated much, much higher, so I really would not trust them, or use them. EDIT: By the way-I mean this in a nice way, I didn't want you to think otherwise, I just wouldn't trust Efest due to their past and current mislabeling of batteries amp ratings.

 

[Wingsfan0310]

The regulated mods I'm familiar with all have input and output amp limits and voltage limits. It's basically up to the user to use batteries that can support the amps they are drawing. The mod has no way of knowing if the user is using a 10amp CDR, 20 amp, etc. Here's a DNA200 datasheet to check out. I usually only buy mods from reputable companies that release a datasheet. If it's a good chip, the company should have nothing to hide:
https://downloads.evolvapor.com/dna200.pdf

For example the DNA200 chip has a 23-24 amp limit (The datasheet says 23 but I believe a firmware update raised it to 24). It has an on-board 25 amp fuse so that's it.

PS Samsung is known for being conservative with their ratings. For example they rate the 30Q at 15 amps CDR but it has been tested by Mooch to be a 20 amp CDR. The 25R is rated by Samsung at 20amp CDR but iirc has been tested to be a 25amp CDR cell.

One other thing with a regulated mod the resistance of the coil doesn't have anything to do with the amp draw from your battery. You dial up the power, the chip sees the voltage present and draws the amount of current to meet the power you have drawn up (+ chip inefficiency). The batteries feed the chip then the chip steps up or down voltage and does the inverse to the current to feed the coil.

Cheers,
Steve

 

[HondaDavidson]

Yeah that's why I have the 25R batteries... I 'm rotating the Efests out. Oh I said rarely vape at over at 10 amps. I forget this is a world of absolutes and alarmism.... I should have said I vape at 4-6amps, well within the Efests tested limits. I have started replacing The Efests, because on occasion I might go as high as 10amps. Thus the Samsungs. Even though NONE of the Efest batteries I have the newest of which is 2 years old, has ever felt hot. Even on those time chain vaping causes the Hot mod and atty to make me think they should be getting hot. I got the Sammy's so I could try some builds below 1ohm, safely. Now that I have picked up a Regulated mod that calls for 25amp batts I'm considering upgrading the 25R's (being that they test at less than 20 amps). I still won't just toss them.... I just wont use them if I ever decide to vape at the upper ends of the mods output.
Yeah it's always confused me as to how the regulated mod could FEED more amps to the atty than it draws from the battery...... I just assumed there was some power being lost/used (increase amp draw) in the circuitry in order to power the device much less regulate the output. I get the volts being bucked and boosted, I just assumed there was a cost in amps from the process. Amps drawn being higher than output. I thought it took power to make power.

 

[Wingsfan0310]

It does that's why I said plus the chips inefficiency (no chip is 100% efficient) in my previous post. The DNA200 is 97% efficient so losses are minimal. It's the most efficient chip I know of in vaping. Obviously not all chips are that efficient. I usually add at least 10% when thinking of worst case scenario. I also mainly use DNA200 chipped mods.

With the DNA200 being a series mod it is buck only which tends to be more efficient. The DNA75 is a buck, boost mod and is rated at 85% efficient.

 

[nightshard]

Because there are such big differences in efficiency it's more accurate to calculate based on your chip efficiency and not just add 10% because there is a huge difference between 3% and 15%

 

[Wingsfan0310]

Because there are such big differences in efficiency it's more accurate to calculate based on your chip efficiency and not just add 10% because there is a huge difference between 3% and 15%

I do. I mainly use the DNA200 and I just add 10% to make sure I give myself a cushion. If I was calculating for the DNA75 I would obviously add more.

For me it's not really an issue since I use 20 amp CDR cells and use TC at 30-35 watts with preheat at 60-75 watts for 1 second.