How low can you build on these batteries? 20S, 30T, and Efest 20700

[Man Called Jane]

Hello everyone...

I couldn't really find any post on this topic, so I figured I would throw it out there.

I have have recently made a purchase from IMR batteries. I am upgrading some of my batteries and got some 21700 for my Karma mech and my Pulse X when it comes out. I have been using 20700 and wanted the extra Amps and mAhs.

So here is the question, how low can you build on some of the batteries below. I have researched using Steam-Engine and read all I could on these batteries from Mooch. Mooch's recommendations actually pushed these batteries to the top of my list.

Samsung 20S 18650
30A 2000mAh
Mooch says this is the only true steady 30A 18650. I want to use them in my AR Mech if possible.

Efest 20700 20700
30A 3000mAh
I have some EBats, that are the same, but have started using them in my Karma mech and just want to be safe.

Samsung 30T 21700
35A 3000mAh
These are Mooch's go to for 21700 mechs. I plan to use them on my Karma mech and in my Pulse X when it comes in.

Lastly
Samsung 25R 18650
20A 2500mAh
I am using these in my regulated mods. Just needed to get an extra pair, couldn't pass it up for $5.99 a pop.

I am experienced with mods and building, but I think I have been doing my math wrong lately, or am putting in the wrong information to Steam-Engine and keep getting weird results. Saying .22 is unsafe for a 30A batteries at 3000mAh and that my .13 on my Zeus RTA is safe. I am using Ohm's Law and the conversion for Wattage and have been just fine in the past. I try to build around .2 to .25, but get a lot lower with the Aliens I enjoy using, between .1 and .15.

Any help or input would be much appreciated. I haven't blown up yet and would like to keep from putting a bad name on the Vape community.

Oh and I got some wraps. Don't forget to re-wrap your batteries. Its easy, cheap, and safe!

And as always, Thank you for your input...

 

[Baditude]

Basically, you use Ohm's Law with your mechanical mods, and use Watt's Law for regulated mods.

I'm horrible with math equations, but I can easily plug in two known values into an Ohm's Law calculator to get two unknown values. You need to know the true amp rating (max. continuous discharge rating) of the batteries you'll be using and the "amp draw" of your coil. (DON'T USE PULSE RATINGS!)

Explain it to the Dumb Noob: Ohm's Law Calculations for a Mechanical Mod​

The amp draw should not be a higher value than the maximum continuous discharge rate of your battery. Better yet, allow some safe headroom to not overtax your battery.

_____________________________________________​

For regulated mods, a different formula is used, Watt's Law. You consider the wattage setting that you will use along with the amp rating of the battery. Mooch made an abbreviated chart to use in the below video, I simply expanded the list of batteries to the chart below:

Are you using a single, dual, or triple battery mod? In the interests of keeping things simple:

-If you use a good quality 15 amp CDR battery like the Samsung 30Q or Sony VTC6, then you are good up to 45 watts per battery; 90 watts using two; 135 watts for three batteries.

-If you use a good quality 20 amp CDR battery like the LG HG2 or Samsung 25R then you are good for 60 watts per battery. If using a 2-battery regulated mod, you're good for 120 watts as you have two batteries. If you are using a 3-battery mod, you're good for 180.

-If you use a single 25 amp CDR battery like the Sony VTC5A, then you are good for 75 watts per battery, 150 watts for two batteries, and 225 watts with three.

-If you use a single 30 amp CDR battery like the LG HB6 you are good up to 90 watts; with a pair of 30 amp CDR batteries you could safely do 180 watts.​

WATTAGE PER SINGLE BATTERY on REGULATED MOD:
(wattage doubles using two batteries; triples using three)

Up to 45W:

Samsung 18650 30Q, 3000 mah 15 amp CDR

Sony 18650VTC6 3000mAh 15 amp CDR

Up to 60W:

LG 18650HG2 3000mah 20 amp CDR

LG 18650HE4 2500 mah 20 amp CDR

Samsung 18650-25R, 2500 mah 20 amp CDR

Sanyo UR18650NSX, 2500 mah 20 amp CDR

Sony 18650VTC5, 2600 mah 20 amp CDR

Sony 18650VTC4, 2100 mah 23 amp CDR

Up to 75W:

LG 18650 HD4 2100 mah 25 amp CDR

LG 18650 HD2 2000 mah 25 amp CDR

Samsung 18650-24S, 2500 mah 25 amp CDR

Sony 18650VTC5A, 2500 mah 25 amp CDR

Up to 90W:

LG18650HB6 1500mah 30 amp CDR

LG18650HB2 1500mAh 30 amp CDR

LG18650HB4 1500mAh 30 amp CDR

Samsung 18650-20S 2000mah 30 amp CDR

​

 

[Topwater Elvis]

Calculating battery amp demand for a mechanical is basic ohms law.
Fully charged battery voltage = 4.2v, always use this if you're not advance enough to know the exact voltage drop of any particular mech set up.
4.2v / .1Ω = 42a.
4.2v / .13Ω = 32a
4.2v / .15Ω = 28a
4.2 / .22Ω = 19a
What is safe? is up to you, I wouldn't push any cell to its full CDR, I always leave a defined % below the CDR for safety margin.

It is never wise to exceed any cells CDR.

When using regulated power device calculating battery amp demand is different.
Mooch explains it here in simple terms --->Calculating battery current draw for a regulated mod | E-Cigarette Forum

Just me, 'how low can you go' is an unnecessary game of chance, if you understand how to build efficiently for the available power source safely there really isn't a reason to get near any cells CDR.

 

[Man Called Jane]

Wonderful! Thank you for your advice.

I would never go this low on these batteries, but if I slip down to .19 or .18 on these with my Mech I should still be safe. These are the extreme dangerous lows for my examples.

From what I have learned and understand now. I was able to calculate the C ratings for these batteries and put them into Steam Engine.

mAh*(1/1000)=Ah

Ah*C=A C=A/Ah

C=A/(mah*[1/1000])

For the Samsung 20S it will max at .14 ohms under the conditions as follows.
Samsung 20S 18650
30A CDR
2000 mAhs
15 C rating
.14 ohms at the max 4.2V will run at 30A on a 2000mAh battery.

For the Efest it is about the same as the 20S due to the higher mAhs.
Efest 20700
30A CDR
3000 mAhs
10 C rating
.14 ohms at the max 4.2V will run at 30A on 3000mAh battery

For the Samsung 30T it will max at .12 ohms under the conditions as follows.
Samsung 30T 21700
35A CDR
3000 mAhs
11.67 C rating
.12 ohms at the max 4.2V will run at 35A on 3000mAh battery

Once again, I would never run this low, but would be safe if my aliens came in at .18 or .19 on these batteries.

As always, Thank you for you help and input!

 

[bombastinator]

I don’t get why the absolute bleeding edge of not blowing up is something you want to get near. This sort of attitude is how cars like this happen
Google Image Result for https://i.pinimg.com/originals/5a/a8/39/5aa83962018514d8ebb18eb41f4ed4c8.jpg

 

[Man Called Jane]

It's not so much about going low for me. It's more of being safe with the builds I like. I get aliens from Jake at my local cloud counters and love the flavor, but they come in about .2. I ask for ones with longer legs to add an extra wrap if I can. Hopefully when I get the hang of building them I can build nichrome kanthal builds or full kanthal and get a higher ohm reading. For now I practice and use their prebuilt ones.

Practice practice practice. If I fail I just get some "okay" claptons.

Sent from my SAMSUNG-SM-G935A using Tapatalk

 

[Topwater Elvis]

Are you going to use single or dual coils?

 

[Man Called Jane]

I mainly use dual when dripping, and singles in when sqonking, but that's on a pulse 80W. Just now I threw some flat claptons in my Drop on my AR mech. They came out to .26 with 6 wraps. Running some Nitro's Cold Brew, nice coffee vape after dinner.

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[Topwater Elvis]

I don't get it, if you use 2 "about .2Ω" coils it should measure .1Ω.

To get .26Ω the coils would have to measure .52Ω each.

 

[Man Called Jane]

Yeah, the aliens I get come in between .38 and .42 depending on how tight he wraps them, so around .2 for dual coils. These flats I'm using right now come in at a .45 per coil with 5 wraps and I added an extra wrap. These are CoilArt "Aliens," but they are actually just claptoned flat wire.

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[Topwater Elvis]

When measuring resistance for use with a mechanical relying on " around " . whatever isn't a good idea.
You need to accurately measure resistance with something capable of measuring low values accurately, not a place for around, about or should be.

 

[Man Called Jane]

I do measure using a 521 mini in my coil master kit. I like the 521 cause it let's me glow my coils and check my resistance as I go. Doing an estamient is just stupid and 30 to 50 bucks a pop everyone should have one, even if you don't build. I have caught some faulty premade coils with it on my sub ohm tanks. It never hurts to check and be safe. That is my main reason for this post. Upgraded my batteries and check my coils. Rather be safe then sorry.

Added note: never use a floating pin sub ohm tank on a mech, especially a hybrid. Never tried it myself, but have heard the stories and seen the aftermath.

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[Chuck64]

This caught my eye even though it's a bit dated because I just purchased three Samsung 20s batteries. I wish @Mooch had seen this and chimed in.

 

[Eskie]

Mooch released a video today explaining all new ratings and "recommended" tables will he released in about a week. You might want to wait to see the latest info unless you already checked a recent review of a newly released battery.

 

[dom qp]

Just want to point something out:

There are diminishing returns that get so bad that after a certain point it doesn't matter anymore. 0.16 has an amp draw just north of 26A. 0.11 is 38A. Is that 0.05 resistance difference worth having to get in an extra 12A?

IMO if you have to nickel and dime yourself because you're so close to the maximum safety ranges, you're doing it wrong. Add a 0.5mm to your coil ID, add an extra wrap, or even just mount it higher. A couple hundreds of an ohm will reduce your amp draw significantly once you get to that low of an area.

This is also why i'm not a fan of prewound coils. You should buy/make spools or strands so that you can wrap them yourself. If you're doing a mech, things aren't so copy paste anymore. You need that extra control to make things safe and perform better.