maths is hard with missing variables

[robthebeck]

I searched and i'm fairly confident my specific question is no where on this site. I've always found the maths with ohms and voltage etc to be confusing for a couple reasons. Mainly, because aside from standalone battery cells, I never see a "C rating/ amperage limit" for most other batteries. so doing the v/o maths in my hypothetical situation, now I have a quotient of 6 amps/25.2 watts that looks to be in the safe vaping range, in accordance with all the charts i can see, but tells me nothing about my battery's ability to safely sustain or administer that level of power. How do you solve this without knowing what battery is in the tube or its amp limit?

Now i know higher power capacity batteries doesn't necessarily mean higher work capacity, so i just want to know what else these mah ratings can account for other than longer life. Specifically, i have a clover overlord, a 2600 mah vv battery, which i have to say, as far as ego batteries go (which i've pretty much used exclusively) is above average. I know what all the seasoned low-ballers will say, "don't sub-ohm on ego style batteries, get a mod" is this a phrase coined before higher capacity egos were available? or is there something fundamental about them that won't allow it? nevertheless i wouldn't intend to use this as an all-day sub ohm set up, i'm quite content with my 1.6 nautilus mini, but i've been looking at an atty that requires something that can fire .7 ohms. again, seems to be in 'the green' at 4.2 volts according to most charts. But i've also heard not to use VV on anything below an ohm. They say to understand what you're asking from your battery, but that's a bit difficult when the batteries/mfgs themselves are seldom ever forthcoming with information about amp limits and the type of battery built-in. Am i making sense or am I stupid for not getting something simple? I have to say, i try my best to do my own research, but one little bit of pertinent info seems to generally be missing from the equation.

 

[bwh79]

I know what all the seasoned low-ballers will say, "don't sub-ohm on ego style batteries

I think the reason for this statement is precisely because you don't know exactly what the battery is inside the tube. Most of them will have a short-circuit protection anyway that won't fire below a certain point, you just may not know what that point is without some experimentation. Other regulated devices have low-ohm cutoff limits as well, they're just usually more up-front with telling you what they are (i.e. an iStick 20w won't fire below 1 ohm, and an iStick 30w won't fire below 0.5, and we know this because it's listed in the advertising and documentation for those devices. You don't get much documentation with an eGo battery, usually.) And with a mech mod, you know the limits because you buy proven reliable batteries from a trusted vendor and so you know exactly what the battery is and what its capabilities are.

 

[Bunnykiller]

you are correct about the lack of info on batteries other than V and mAh rating... deeper searches are needed to find the C rating. As a general rule, the C rating should be the maximum amperage one should draw from the battery in a steady state usage. Unfortunately, someone decided that one can push a battery even further and created a nomenclature of "Pulse" rating. This would be more similar to something called a duty cycle... a short time on and a longer duration time off to let things "settle down". The duty cycle is primarily used in things that require a cool down period, such as transformers under duress. ( example, welding machines pulling hi amps) the main problem with thinking that batteries can behave as transformers with a duty cycle is that batteries dont have windings that can cool down...

I generally use 20A as a C rating and keep my amp draw at 75% of the C rating to insure longer battery performance. Running batteries at the max C rating or beyond reduces the longevity/recycle ( charging cycles) of the battery. Instead of getting 200-300 recharges out of your battery you end up with alot less. Also, pushing the battery beyond the C rating can cause damage to the chemistry and end up with a vented battery....

 

[robthebeck]

I think the reason for this statement is precisely because you don't know exactly what the battery is inside the tube. Most of them will have a short-circuit protection anyway that won't fire below a certain point, you just may not know what that point is without some experimentation. Other regulated devices have low-ohm cutoff limits as well, they're just usually more up-front with telling you what they are (i.e. an iStick 20w won't fire below 1 ohm, and an iStick 30w won't fire below 0.5, and we know this because it's listed in the advertising and documentation for those devices. You don't get much documentation with an eGo battery, usually.) And with a mech mod, you know the limits because you buy proven reliable batteries from a trusted vendor and so you know exactly what the battery is and what its capabilities are.

Right, right, makes sense. I do use this battery quite a bit at 4.4/4.6 volts for better or for worse, but it seems to handle that quite well, and for a long time. i guess ultimately to find out i'd have to experiment. i was just checking to see if anyone here knew this info because it's nowhere to be found apparently, and also the threading on the .7 atty in question wouldn't be able to attach to most box mods.

 

[robthebeck]

anyways thanks for the answers.

 

[edyle]

.... ...

Am i making sense

If you could ask a specific question perhaps there can be an answer;

so far my guess is your battery has some ohm limit anyway, perhaps it's 0.5 ohms or perhaps it is 1.2 ohms if its one of the older ones.
It sounds like a regulated battery.

But with those fixed battery things you have to keep in mind they are going to be spunkier when they are young and strong, but when they get older you can find they get hotter faster.

 

[Topwater Elvis]

There really isn't any way to tell what the battery inside of an ego type can sustain safely.
There are more clone/knock off ego type manufactures than you can shake a stick at.
Most have 'built in' amp limits that won't allow them to fire below a certain resistance that exceeds the amp limit, most work some don't.
I wouldn't trust or use any ego style battery to fire .7.
Most twist style batteries amp limit falls between 2.5a ~ 3.5a.

Even at 3.7v the .7 will draw more than any ego battery I know of can safely supply 5.2 amps.
4.2v /.7 = 6a
4.8v / .7 = 6.8a

If you want to safely fire sub ohm resistances you should use a power device & battery designed to support the amp drain.

 

[robthebeck]

If you could ask a specific question perhaps there can be an answer;

so far my guess is your battery has some ohm limit anyway, perhaps it's 0.5 ohms or perhaps it is 1.2 ohms if its one of the older ones.
It sounds like a regulated battery.

But with those fixed battery things you have to keep in mind they are going to be spunkier when they are young and strong, but when they get older you can find they get hotter faster.

basically what i can do to determine the amp limit, or if it would be safe to attempt to run aforementioned ohms on it. considering i've seen aspire has a 2000mah sub ohm tube mod, i was just wondering what difference in functionality there might be compared to my 2600mah clover, im guessing if anything the aspire even with the lower capacity supplies a higher current. amp limits just seems to be a frequently absent piece of important info, i guess i'm saying, but bwh79 covered that. It's fine i think i'm going to go with the aspire cf subohm, unless there are well established objections to that.

 

[VHRB2014]

Concentrates?

 

[Izan]

 

[edyle]

basically what i can do to determine the amp limit, or if it would be safe to attempt to run aforementioned ohms on it. considering i've seen aspire has a 2000mah sub ohm tube mod, i was just wondering what difference in functionality there might be compared to my 2600mah clover, im guessing if anything the aspire even with the lower capacity supplies a higher current. amp limits just seems to be a frequently absent piece of important info, i guess i'm saying, but bwh79 covered that. It's fine i think i'm going to go with the aspire cf subohm, unless there are well established objections to that.

well basically if it's a regulated ego type battery, if you put too low ohms on it it's just not going to fire; if you check and find that it doesn't fire a 1.2 ohm or less coil, at 4.2 volts then the amp limit sounds like around 4.2/1.2 = 3.5 amps