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battery/ohms law question

vasoline_slurpee

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I have these AOSO 18650's (40A, 2500mAh) batteries and I've been wondering..what's the lowest ohm build I could safely use on a mech mod with this battery? Also if you know a simple equation i can use for the future that'd be great:)
Thanks
 

ej1024

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I have these AOSO 18650's (40A, 2500mAh) batteries and I've been wondering..what's the lowest ohm build I could safely use on a mech mod with this battery? Also if you know a simple equation i can use for the future that'd be great:)
Thanks

Where did you buy these batts?


I BAM
 

IMFire3605

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IMRBatteries, illumn.com, nor Liionwholesale.com have them in stock or listed as a product.

That aside, I'll put it bluntly, there are no 35 or 40amp CDR batteries in 18650 format, the main big 4 battery manufacturers just don't make them with both high CDR (your supposed 40amps) and a high Mah (2500mah is just to high for a super high CDR battery), only 3 ways they, with current chemistry can make an 18650, 1) low mah with High CDR (example the LG HB2, HB4, and HB6 series @1500mah and 30amp CDR), 2) high Mah and Lower CDR (example Samsung 30Q @3000mah 20amp CDR), or 3) a balance between the 2 median Mah and Median CDR (example Sony VTC5A @ 2500mah 25amp CDR). Those Big 4 manufacturers are LG, Samsung, Sony, and Panasonic/Sanyo, from the most likely perspective that AOSO could actually be a B or C Bin (did not pass muster to be an A Bin Authentic) Samsung 25R @ 2500mah and 20amp CDR or LG HE2/HE4 @ 2500mah and 20amp CDR underneath that wrapper, or an even worse situation a Chinese Cloned version of any of the Authentic 2500mah batteries out there. That 40amp rating is the short 1/2 to full second pulse discharge rating on any of those 2500mah batteries, after that pulse duration the battery needs to be shifted down to its 20amp CDR or it will over heat "Badly", cook itself to death and then if you continue to use it that way for a couple months it is a potential time bomb waiting to go boom on you. Using it in a mech, I'd treat it like a Samsung 25R, 0.3 to 0.35ohms lowest, in a regulated I'd treat it the same way 60watts per battery max single battery, 120watts dual battery, etc, and being a brand I wouldn't trust just like Efest, AWT, IMRen, Sub-ohm Cell, Baisen, I'd run them in a regulated mod only 50watts per battery maximum, for a mech, even myself which I have several mechs, Sony VTC5A top of the mech battery list, followed by the LG HB2, HB4, HB6, Sony VTC4, and Samsung 25R.
 

conanthewarrior

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Like @IMFire3605 said, there isn't any 35 or 40A 18650's, and I am always skeptical of rewrappers that post inflated specifications.

It is very likely either a 20A Samsung 25R, LG HE4, or at best a 25A Sony VTC5A. Could you give us a picture of the top of the battery? We can then have a look at the number of prongs and estimate what manufacturer made the battery.

The only thing is that is all it will be, an estimate. We, and you, have no way of really knowing what battery that is under the wrapper. For all we know they could of done an Efest, and it is really a 6A battery.

I would actually not use these batteries from Mooch's tests of other AOSO rewraps, seen here- https://www.reddit.com/r/electronic_cigarette/comments/4v5pih/aoso_red_42a_2600mah_18650_bench_test/

https://www.e-cigarette-forum.com/f...t-results-most-overrated-18650-so-far.757059/

The second one is the most over rated 18650 he has ever tested, and got hot enough to boil water during his tests.

It is not worth using these for safeties sake in my honest opinion, but if you are intent on using them I would rather try to help tell you what they could be than you using them as 40A batteries.
 

vasoline_slurpee

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@conanthewarrior @IMFire3605
Wow, thank you for all of this.
So I guess what I need to know now is what batteries should I be using on a mech mod building around 0.1 ohms. Sometimes I dip around 0.07 but when I do that I use a regulated box mod instead.
 

IMFire3605

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@conanthewarrior @IMFire3605
Wow, thank you for all of this.
So I guess what I need to know now is what batteries should I be using on a mech mod building around 0.1 ohms. Sometimes I dip around 0.07 but when I do that I use a regulated box mod instead.

Absolute Safest Lowest Build on a Single Battery Mech is bout 0.2 to 0.25 (LG HB2, HB4, HB6 1500mah 30amp)

4.2v/0.25=16.8amps
4.2v/0.14=30amps <-- but a single battery won't stay at this level of CDR after continuous abuse such as this, you'll cook the battery and change its chemistry which will affect its Mah and affect the mah, the CDR decreases with that decreased mah.

The level you are are asking for is in the dual battery "Parallel" box mech mod territory where in theory you gain X number of batteries to CDR and Mah though at the same voltage of a single battery, in practice you gain 50% per extra battery, example dual battery with LG HB6 30 amps, total combined load both batteries together can handle would be 45amps.

If you are absolutely needing to be down that low, keep those builds for your regulated mods in case of an accidental short or misfire where the control board is there as a fuse and safety buffer, in a mech there is no safety mechanism other than the grey matter above your shoulders.
 

KingPin!

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If you're not sure who real manufacturer is safest bet is to assume this is a 16CDR battery work with it that way at least that's probably what I'd do assume it's an efset or something
 

conanthewarrior

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@conanthewarrior @IMFire3605
Wow, thank you for all of this.
So I guess what I need to know now is what batteries should I be using on a mech mod building around 0.1 ohms. Sometimes I dip around 0.07 but when I do that I use a regulated box mod instead.

@IMFire3605 has given you a great answer to this, for a tube you wouldn't really want to push a battery that far with a build that low- people do, for competitions and such, but it is beyond what the battery is designed for.

A parallel box would be needed for builds that low on a mech to give you the headroom to stay safe.

For when you want to build very low, I would go regulated for safeties sake, as resistance doesn't effect amp load on your batteries with a regulated mod.
But then again, when you are regulated there isn't really a need to go as low as you can adjust the power, so you wouldn't need to build at 0.07 (Unless you was using something like Ni200 for TC).

And what @KingPin! said is pretty good, I would treat the batteries as if they had a slightly lower amp rating than the most popular 20A cells. Pushing them won't result in instant problems, but always best to stay safe :)
 

vasoline_slurpee

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@IMFire3605 has given you a great answer to this, for a tube you wouldn't really want to push a battery that far with a build that low- people do, for competitions and such, but it is beyond what the battery is designed for.

A parallel box would be needed for builds that low on a mech to give you the headroom to stay safe.

For when you want to build very low, I would go regulated for safeties sake, as resistance doesn't effect amp load on your batteries with a regulated mod.
But then again, when you are regulated there isn't really a need to go as low as you can adjust the power, so you wouldn't need to build at 0.07 (Unless you was using something like Ni200 for TC).

And what @KingPin! said is pretty good, I would treat the batteries as if they had a slightly lower amp rating than the most popular 20A cells. Pushing them won't result in instant problems, but always best to stay safe :)

I appreciate all the help you guys. I'm going to browse for a parrallel mech box mod and some HB6's so I can vape .1 without having to worry about messing up my batteries(or face). If you have a suggestion for finding either of these, I'd appreciate the direction.
thanks again:)
 

Rabbit Slayer

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Mooch posted about those...

AOSO 40A 2500mAh 18650 Bench Test Results...wildly overrated, only a 20A battery

Bottom Line: This is just a wildly overrated 20A cell with a 2500mAh capacity rating. At 30A continuous, which is 10A below its rating, it gets hot enough to boil water


oops, someone already posted that info
 

conanthewarrior

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I appreciate all the help you guys. I'm going to browse for a parrallel mech box mod and some HB6's so I can vape .1 without having to worry about messing up my batteries(or face). If you have a suggestion for finding either of these, I'd appreciate the direction.
thanks again:)

Sounds a good idea on the parallel box. The HB6 will be the ultimate in safety, although you could use the VTC5A for a lot more capacity. This will be a bit over the 50% extra most people use for safety, although parallel does offer double- people just use 50% to be extra safe so the VTC5A would still be a good choice.
If you are OK with the sacrifice in capacity though, the HB6 is perfect. It will still give you better battery life than a tube mech with a single 18650 :)
 

vasoline_slurpee

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@conanthewarrior This may be a stupid question but I'm damn curious.. does each battery you add in parallel increase the theoretical amp limit?
So would a three battery parallel mech give you a 75A cap (using 25A batteries)? 4 batteries @ 100A, ect.? or is there some law I'm missing out on?
 

IMFire3605

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@conanthewarrior This may be a stupid question but I'm damn curious.. does each battery you add in parallel increase the theoretical amp limit?
So would a three battery parallel mech give you a 75A cap (using 25A batteries)? 4 batteries @ 100A, ect.? or is there some law I'm missing out on?

In "Theory" with parallel battery sleds, you gain that much CDR each extra battery in the parallel circuit, plus the mah is the same as the loads are balanced between the batteries, but in practical intents and purposes, the closer you get to absolute 0 resistance (0 Ohms) you get that much closer to in reality a dead short, or for us and most electronics, once you reach close to that level the only resistance in the whole circuit is the internal resistance of the battery, thus you put the full load on the batteries. This is dangerous, not to mention, take this into consideration, arc welders a lot of times use DC, not AC power or convert AC to DC to do welding with, your typical car lead acid battery is 500amps plus DC @ 12v or so. It takes about 100 to 200amps to weld with, so you can run a welder off a car battery, also all it takes is 1amp to stop your heart, you really want that much current (amps) near your face or anywhere near your body under load? Even potentially as you state with 4 25amp VTC5A in a parallel mech box, yes it is feasable and theoretically possible, but you still have to figure in safety margin and mishap shorts at either the coils or the firing assembly, thus most suggest 50% per extra battery added in.

Even on such a device, 0.1 to 0.15 is still your absolute lowest you should build on a parallel box mod, so 4 25amp batteries in parallel you get for safety margin, 1 X 25 amps (first battery closest to the coils), 3 X 12.5amps (50% each) for 37.5 extra amps, 25 + 37.5 = 62.5amps total spread balanced between those 4 (62.5 / 4 = 15.625amps each battery has to handle).

Another set of factors to take into consideration, closer you get to maximum CDR on a battery, the hotter it gets, basic principle of chemistry, you heat things up, you change the chemical molecular structure of the battery internally, do that you decrease its capacity (mah) and through put (C or Current Rating), decrease either of those 2 or both the CDR decreases as well, so heavy max abuse literally cooks a battery to death making it more dangerous the more abuse you put it through. Batteries also decrease Mah over time whether charged or discharged due to the acidic nature of the "Electrolyte" solution that is used to make chemical electric reactions that make batteries function, the moment they are assembled they are on a ticking timer, same aspect and previous decrease the Mah you decrease the CDR. Using a battery at max 50% to 75% of its max potential helps take this aging and decrease into account, a VTC5A brand new can do 25amps, heavy daily 25amp abuse that battery is now 12.5amps max in 30 to 60 days, but in the same retrospect, using it at 12.5amps daily it can be 6 months to 12, maybe 18months before its ability is down to that 12.5amp limit due to age. Yes it may sound exciting to have a 100amp coil build, 0.04ohms/4.2v=100amps at 420watts, this is no where near safe nor advised, as there is no room or margin for error to accurately measure that 0.04ohms spot on with your average mod resistance reader or $10 ohm reader, to gain that accuracy the "Reader" needs to read not at X.xx where you are gauging things, but at X.xxxx (4 or more decimal points) and those types of meters are in the $500 USD plus price range.
 

KingPin!

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@conanthewarrior This may be a stupid question but I'm damn curious.. does each battery you add in parallel increase the theoretical amp limit?
So would a three battery parallel mech give you a 75A cap (using 25A batteries)? 4 batteries @ 100A, ect.? or is there some law I'm missing out on?

Notice what imf said there in the first few lines theoretically in parralel you gain double but you don't actually due to the leads not being exactly equal so there isn't actually equal load on all the batteries mooch said he normally sees about a 15% reduction in the amp of the next battery in the string whether this applies to each battery im not entirely sure I doubt it does but it must reduce to a point for theoretical limit depending on the length of the connecting wires in the string
 

vasoline_slurpee

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Notice what imf said there in the first few lines theoretically in parralel you gain double but you don't actually due to the leads not being exactly equal so there isn't actually equal load on all the batteries mooch said he normally sees about a 15% reduction in the amp of the next battery in the string whether this applies to each battery im not entirely sure I doubt it does but it must reduce to a point for theoretical limit depending on the length of the connecting wires in the string

So realistically, using 2 vtc5's in parrallel on my noisy cricket v2, I should only build down to about a .13 - .15 range? instead of assuming the amp load would be doubled?
I know i'm asking a lot of questions but I just don't want to end up in the paper.. :bomb:
 

KingPin!

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VTC5 has a CDR rating of 20, so in parralel I would personally combine with a 30a limit to err on side of caution

Next bit is ohms law

(A1) Max voltage at full charge in parralel =4.2v
(A2) Battery sag = 10%
(A3) Resistence of the coil = 0.13

(A5) Current drain is I = V/R
29.08amps
In excel you can do this as
=(A1-(A1/100*A2))/A3

Wattage is P = V x I
109.91watts
In excel you can do this as
=(A1-(A1/100*A2))*A5

Note and this is important ...,this only applies to mechanicals it doesn't work like this on regulated mods

Also on mechanicals as voltage drops so does everything else
 
Last edited:

conanthewarrior

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Great answers have already been given to your question, although I will reply as you asked :).

If everything was perfect, you would indeed achieve such an increase, with dual parallel and 25A batteries 50A for example.

In the real world though, things are not perfect, which is why the 50% margin is used for safety. It is likely you can push more than this safely, but without knowing how far you can really go it is better to stay on the safe side of things.

I gather it is power you are after seeing as you are building so low? I see you have a Noisy cricket V2, have you thought about running this in series instead of parallel? With this you can build higher but still achieve a very powerful vape.

For example, lets use 0.5. In parallel, you would get at a maximum just over 35W, at 8.4A.
In series, still at 0.5, this would give you a whopping 141 Watts! The amp load would be 16.8A, so still on the safe side of things. You also NEED to build coils with a lot of surface area for series, so if you want power, big clouds, using big coils, series is great.

Make sure you follow all of the standard safety precautions and you will be fine. It really is a different beast series, and until you try it is very hard to explain the type of vape it gives.

For the parallel, I would stick to 30A as this is the 50% limit. Never worry about asking lots of questions, it is much better you do than have an accident- I probably did peoples heads in when I first joined here with questions that seemed so simple.
Even if I was 99% sure of an answer, I would ask, and I still will now. Better to be safe than sorry!
 

vasoline_slurpee

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Great answers have already been given to your question, although I will reply as you asked :).

If everything was perfect, you would indeed achieve such an increase, with dual parallel and 25A batteries 50A for example.

In the real world though, things are not perfect, which is why the 50% margin is used for safety. It is likely you can push more than this safely, but without knowing how far you can really go it is better to stay on the safe side of things.

I gather it is power you are after seeing as you are building so low? I see you have a Noisy cricket V2, have you thought about running this in series instead of parallel? With this you can build higher but still achieve a very powerful vape.

For example, lets use 0.5. In parallel, you would get at a maximum just over 35W, at 8.4A.
In series, still at 0.5, this would give you a whopping 141 Watts! The amp load would be 16.8A, so still on the safe side of things. You also NEED to build coils with a lot of surface area for series, so if you want power, big clouds, using big coils, series is great.

Make sure you follow all of the standard safety precautions and you will be fine. It really is a different beast series, and until you try it is very hard to explain the type of vape it gives.

For the parallel, I would stick to 30A as this is the 50% limit. Never worry about asking lots of questions, it is much better you do than have an accident- I probably did peoples heads in when I first joined here with questions that seemed so simple.
Even if I was 99% sure of an answer, I would ask, and I still will now. Better to be safe than sorry!
Thank you to all.
I actually have the original noisy cricket but I haven't used it in a while. What type of build works best on that series box? I have materials for clapton, fused clapton, twisted, ect. Only wire I have none of is ribbon.
 

conanthewarrior

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Thank you to all.
I actually have the original noisy cricket but I haven't used it in a while. What type of build works best on that series box? I have materials for clapton, fused clapton, twisted, ect. Only wire I have none of is ribbon.

I have the original noisy cricket too- I find that some simple 3.5MM, 26G SS316L coils , about 12 wraps a side, gives a really nice vape.

It is still pretty rowdy though- even with all that surface area the ramp up is instant, and the vapour is very warm, with massive clouds. I would stick above 0.4 and you will still get great results :)
 

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