efest 18650 35A??

[vdsteven]

I just bought a pair of efest 18650 35a purple batteries and i've been looking online at different forums and people are saying they're rewrapped lg's 20amp.

even if it is rewrapped, will it be safe for a single or dual parallel coil build on a plumeveil 1.5? whats the ohm limit on 20 amp and 35 amp?

 

[Neolithium]

The ohm limit on the efests IS IN FACT 20 AMP. 35amp is pulse max. I can comfortably go down to 0.25 ohm on these and not worry at all. Realistically you should not be aiming for any build in the pulse draw, ALWAYS shoot for something below the continuous draw.

Also from what I gather on your post, you should spend some time googling the battery safety guidelines and other manner of safety for mechanical mods. If you're not going for competition cloud chasing, I highly doubt you'll need lower than 0.25ohm

 

[Warpigs]

Try to get yourself some Sony US18650VTC4 2100mAh 30amp - RTD vapor. They are wonderful. I got myself 7, well worth the money.

 

[Brandon David]

I use the purple Efests in my mech/dripper setup with .4-.6 ohm as well as my sigelei 100+ around 1 ohm and have absolutely no issues. I've been carrying the sigelei with me for the last 3 days and the batteries are generally down to about 60-65% by the time I throw them on charge and hit the sack. I chain vape a good bit so that's with heavy use at 35 or so watts.

No complaints here.

 

[K_Tech]

whats the ohm limit on 20 amp and 35 amp?

Briefly, you use the voltage of a fully charged battery (4.2 volts) in your calculation, and current = voltage divided by resistance. If you know your current and voltage, you can solve it "backwards" to see what your resistance limit should be.

So, 4.2 volts divided by 20 amps is 0.21 ohms, and 4.2 volts divided by 35 amps is 0.12 ohms.

If you have a smartphone, you can get an app called "steam engine" that has built in calculators for a bunch of different vape-specific things. (I know it's available for Android, not sure about iOS) and they also have a website that you can use.

*Edited to add most people (including myself) would suggest staying away from the hard limits to give your battery a little breathing room - this is even more important when your battery starts to age/degrade.

 

[vdsteven]

Nemesis hcigar, 18650 purple efest 35A, plume veil 1.5, and either single or dual parallel coil build.... am i safe here?

 

[EnigmaX]

Totally safe. I can run an efest purple in my .2 all day with no problems. I use vtc4's but the efest are back up

 

[vdsteven]

thanks guys

 

[JimmyDB]

I just bought a pair of efest 18650 35a purple batteries and i've been looking online at different forums and people are saying they're rewrapped lg's 20amp.

even if it is rewrapped, will it be safe for a single or dual parallel coil build on a plumeveil 1.5? whats the ohm limit on 20 amp and 35 amp?

Nemesis hcigar, 18650 purple efest 35A, plume veil 1.5, and either single or dual parallel coil build.... am i safe here?

vdsteven, I never saw YOU tell us what your coil resistance was... which is generally more important than the mod style, manufacturer or atomizer.

Simply put...

Max battery voltage divided by stated continuous current discharge [CCD) for battery = lowest resistance to use
Companies that just rewrap and only advertise the pulse rating can change what battery they are rewraping, which can change the CCD. If they are only advertising a pulse rating, then that's all they have to maintain. If you look though, i think you can find a proper datasheet for your battery, I just wanted to be clear about rewraps.

or

( Max battery voltage divided by stated continuous amperage for battery ) times 1.1 = lowest resistance to use with a safety margin

4.2 (max for most Li+) divided by 20A (CCD of eFest 35A pulse) -> 0.21 Ohms

0.21 * 1.1 -> 0.23 Ohms. With this, you would start at around 77W instead of 88W... which is where you would have been at 3.9V with 0.2 Ohms any way...


4.2^2/0.21 -> 84W and 84W / 4.2V -> 20A

4.2^2/0.20 -> 88.2W and 88.2W/4.2V -> 21A


As you get close to the limit it's good to remember that the mod itself causes a voltage drop, and that drop goes up with the current draw... and the battery will sag and output less voltage when under load. If you build your set up based on everything at a rest state, no-load battery voltage of 4.2 and just read the atty resistance, you should have some built in safety right there since the mod+center pin will resist the higher current preventing you from ever getting your calculated numbers.

 

[drunkenbatman]

Are we allowed to swear in these forums? As ....... Efest again for their labeling on this one. Seriously, ... Efest.

 

[K_Tech]

Are we allowed to swear in these forums? As ....... Efest again for their labeling on this one. Seriously, ... Efest.

I agree. It's one thing when you know what you're buying (I own four of these Efests, but I don't go crazy sub-ohm, and have been using them in regulated mods anyway) but a new vaper at the shop with no knowledge of batteries...?

That could be bad.

 

[Neolithium]

I agree. It's one thing when you know what you're buying (I own four of these Efests, but I don't go crazy sub-ohm, and have been using them in regulated mods anyway) but a new vaper at the shop with no knowledge of batteries...?

That could be bad.

Research is a big part of it too. Sub ohming in general mandates that people spend some time learning not only about the coils, wicking, ohms law, etc. But also all the details of the batteries they are using. Took me less than 3 minutes on google to find out the true continuous draw on the efest batteries, and they still can truly pulse to 35A. Any time I see these in a post I mention the true CD rating these have, and I've still comfortably taken these ones down to 0.24ohm. 0.21 on an experimental build that lasted a week, without any issues. If people TRULY were worried they'd use nothing but SX30's in every build for subohm but that rarely happens except for competition cloud chasers who want the best, not armchair Nikola Teslas like myself.

 

[drunkenbatman]

Research is a big part of it too. Sub ohming in general mandates that people spend some time learning not only about the coils, wicking, ohms law, etc. But also all the details of the batteries they are using. Took me less than 3 minutes on google to find out the true continuous draw on the efest batteries, and they still can truly pulse to 35A.

I agree, though in fairness, I googled one of my batteries to double check the other night and saw it's safe Ohm listed as 0.5 ohm some places, 0.3 in some and 10a in some and 18a in others and 20a in some. So had to go double check the specifications and to the math manually (slowly, because I like turtles) but most would think they had done their research.

And well, yes it may pulse to that -- but no one would have expected that rating to mean that, just like you don't buy a post for a load-bearing wall rated for 1,200lbs only to be told "Oh, that's only for 10 seconds." It's just not responsible, and kind of hard to defend, yah know?

 

[JimmyDB]

So...

I went ahead and contacted efest in search of datasheets. I know others have done this, but it's always worth a shot. Here are the datasheets...

Efest IMR 18650 battery 20A purple efest 18650 3100mah 3.7V rechargeable battery

Newest Efest 35A IMR 18650 2500mah flat top rechargeable battery perfect for ecig

Yes... that's what I got when asking for datasheets... and I only got that after a few emails back and forth because they wanted to send me a price list and not datasheets because...

because seldom customer need datasheet

So... please turn your attention to the 2500mAh graphic...
"Max continuous discharge current" -> 35A
"continuous discharge current" -> 20A
"Plus discharge current" -> 50A

When I asked about 'Plus' and explained I am familiar with 'Pulse' but not 'Plus' and that is one of the reasons for needing a datasheet... along with being confused about a MAX continuous rate paired up with a continuous rate... they said... [and I quote]...

The 'Plus Discharge Rate' is max, we always print the continuous and max plus discharge rate on the battery,

Not sure about your efest batteries... but after checking the few I have... none of them have the "continuous and max plus discharge rate on the battery" printed on them in a way I can read it... I'm going to break out the blacklight because I know efest doesn't lie I may have to send another 400 emails from 400 different accounts over their next holiday asking what magic I must invoke to be ABLE to read what is ALWAYS printed on the batteries.

So... overall, they are very confused and don't actually have datasheets. I told them that I didn't even care if they weren't the manufacturer... just send me the datasheet from the manufacturer and they danced around that one and insisted they are the efest factory?! Ok...

So... after all of this, what I have learned is that I'll probably assume the true spec is 1/2 of their 'continuous' rate and just not buy any more of them... not when I am buying LG HE2's and the like for the same price.

 

[drunkenbatman]

Hey JimmyDB?

I just met you, and this is crazy? But here's my number, so call me maybe?

Seriously mate, hella post; wish it was mine. Utility belt still tingling.

 

[K_Tech]

So... please turn your attention to the 2500mAh graphic...
"Max continuous discharge current" -> 35A
"continuous discharge current" -> 20A
"Plus discharge current" -> 50A

That just bugs the crap out of me, more so because it comes from the supplier. Seriously, do they not understand what they are publishing, and do they not have technical writers to proofread this junk?

 

[Ryedan]

So... after all of this, what I have learned is that I'll probably assume the true spec is 1/2 of their 'continuous' rate and just not buy any more of them... not when I am buying LG HE2's and the like for the same price.

Excellent post Jimmy. I don't know how much you're paying for LG HE2's but Illumination Supply has Samsung 25R for $6 a pop and they are a very reputable supplier. The 25R is at least as good as the HE2 IMO.

Vape on my friend

 

[Ryedan]

That just bugs the crap out of me, more so because it comes from the supplier. Seriously, do they not understand what they are publishing, and do they not have technical writers to proofread this junk?

Yup, I totally agree K_Tech. They can also change the battery under the wrapper anytime without notice. Not a good thing for us.

 

[drunkenbatman]

Ah, I'm really looking forward to taking those samsung's for a run once I wear mine out a bit and the vape budget refills; I saw a pair for $14.50 w/case from a less-reputable supplier on ebay and came close. Butthey will be mine one day.

Speaking of being mine, I have good news! JimmyDB accepted, and has now become my first friend. The floodgates are now open, but he's first in the paper mache diorama.

 

[JimmyDB]

That just bugs the crap out of me, more so because it comes from the supplier. Seriously, do they not understand what they are publishing, and do they not have technical writers to proofread this junk?

They sure don't understand it. They are just buying/rewrapping and selling. I'm not even sure they re-wrap in-house... I get a bad feeling that they don't. I'm kind-of surprised as I have dealt direct with manufacturers in the past, and they are ON TOP of the game and very cautious. I was quite shocked when I first starting learning about efest. I haven't dealt with much in the line of these cylindrical ones though... it seems to be a bit different than dealing with packs [soft or hard shell cells].

Excellent post Jimmy. I don't know how much you're paying for LG HE2's but Illumination Supply has Samsung 25R for $6 a pop and they are a very reputable supplier. The 25R is at least as good as the HE2 IMO.

Vape on my friend

I think I paid $7 for the HE2's and bought a bunch... was either $7 or $8. I would have to see who I got them from, but it was a battery supplier versus a vape shop/company.

Yup, I totally agree K_Tech. They can also change the battery under the wrapper anytime without notice. Not a good thing for us.

This is the part that bothers me the most. All they put on the battery is a discharge rate... doesn't say MAX or anything... so, as long as that rate is <= the max for whatever battery they go with... they are basically free to do as they please. Note also that they don't assign exact product codes publicly... making it even harder to know which is which... as far as their web site, well... we all know how easily that can change.

When you are selling a high energy-density, sealed, metal tube, that can also release energy very very quickly... trust starts to play a big role in things. I have a hard time trusting them if they failed at copy/pasting 'Pulse' and it ended up being 'Plus'. I understand and can look past dubious marketing, like making 35A huge along with the 2500mAh, but I just want the tech specs and to know that if they change... I can reference which ones apply to what I have and can get the proper docs quickly.


UPDATE: That reminds me... check out the charge cut-off... 4.2V +/- 0.5V... not 0.05V?