New batteries?

[cloudyjosh]

Heya guys I've been using efest 35A for past 7 months and there dying! Going to get some new ones soon and not sure what to get because when I got the efests I was using mech mods and now I am using 70W VV devices down to .2 ohm. Do I need efests again or is there a cheaper/better alternative? Cheers

 

[Teresa P]

http://liionwholesale.com/collectio...mah-flat-top-wholesale-lot?variant=1038201992

 

[Angrygod50]

liionwholesale.com Samsung 25R, LG HE2, HE4 OR HG2 Are all good. I'm under the impression that most efest batteries are re-wraps of one of these. The 35amp is misleading (max rating) as the highest continuous rated battery is the Sony vtc4 at 30amp.










At 70w any of these will serve you well.

 

[cloudyjosh]

Awesome cheers guys and yeah I've seen 50A 18650's before but not sure what Mah they were :/

 

[cloudyjosh]

How does it work? Because if it was in a mech mod .2 ohm-75W-4.97V would draw more than 20A? How come it doesn't vent?

 

[Mooch]

liionwholesale.com Samsung 25R, LG HE2, HE4 OR HG2 Are all good. I'm under the impression that most efest batteries are re-wraps of one of these. The 35amp is misleading (max rating) as the highest continuous rated battery is the Sony vtc4 at 30amp.

At 70w any of these will serve you well.

There's the HB2 and HB6 too.

 

[Mooch]

How does it work? Because if it was in a mech mod .2 ohm-75W-4.97V would draw more than 20A? How come it doesn't vent?

In a mech you would draw 4.2V / 0.2 ohms = 21A worst case, and not for very long. No danger of a 20A battery venting there.

 

[Jimi]

Maybe it's just, me but I'd rather be on the safe side with the vct4s just buy a few spares.

 

[Angrygod50]

Batteries have a continuous and pulse rating. A quality 20A continuous rated battery will deliver higher current safely for a short duration.
I think the higher ratings on re wraps is a pulse rating I have some Imren's that say 40A max but I wouldn't try it. At least they say max not continuous and when I opened one up it had the markings of a Samsung under the wrapper.

 

[battery bro]

And also keep in mind a pulse rating is defined as current / time.

50A or 35A is just a current rating, not a pulse rating. Time is the missing component of many fake pulse ratings.

A pulse rating it something like "30A for 2 seconds".

 

[Mooch]

And also keep in mind a pulse rating is defined as current / time.

50A or 35A is just a current rating, not a pulse rating. Time is the missing component of many fake pulse ratings.

A pulse rating it something like "30A for 2 seconds".

And add in max temperature for that rating too. No good if operating at the rating causes lots of damage to the cell.

 

[battery bro]

And add in max temperature for that rating too. No good if operating at the rating causes lots of damage to the cell.

Very true. Best not to exceed 60 Celsius, however 18650 are typically rated to handle 70 - 80 C.

The more you deviate from the standard 25 C most 18650 cells love, the more stress and the faster the degradation.

 

[NemesisVaper]

How does it work? Because if it was in a mech mod .2 ohm-75W-4.97V would draw more than 20A? How come it doesn't vent?

Any OEM 20A will be good for a 70W single cell regulated device. There's nothing seriously wrong with efest but I wouldn't recommend anyone buy them if they don't already have them.

Amp draw works differently on a regulated device. With a mech you use battery voltage and coil resistance to calculate. For a regulated device you take the wattage you have set and divide by the voltage the mod let's the battery go down to before it shuts off.

For the example you provide, the mod battery won't be at 4.97V, that's the voltage the board is giving to the atty. The board will create a load dynamically that, when plugged into ohms law along with current cell voltage, gives that 75W to the atty. As voltage in the battery drops, the board will create a bigger load, to maintain that 75W draw from the cell. You'll need either a mod that shows actual battery voltage or a multi meter to know what is being drawn at a specific time.

For a single cell mod use the equation [Set wattage] ÷ 3.2V. Most single cell devices shut off at about 3.2V minimum. For a single cell series mod use 6.4V, and for a parallel mod eg istick 100W also use 3.2V,thebsame as for single cell.

Note that at 70-75W a single cell device won't last long. It also likely won't cut off at 3.2V when set so high. In my testing if the Koopor Mini, at its max 60W it cut off at 3.5V with all batteries I tested.

 

[Jimi]

I just like to have a little bumper, better safe than sorry, I have a black cloud that follows me everywhere. I also still have both hands HAHAHA.

 

[NemesisVaper]

I just like to have a little bumper, better safe than sorry, I have a black cloud that follows me everywhere. I also still have both hands HAHAHA.

Nothing wrong with being safer. There are always options for higher discharge cells. Anyone not wanting to push a 20A with a single cell 70-75W mod, there's the LG HD2 which is 25A and 2000mAh. Of course you could always use a VTC4, Jon sells genuine cells.

 

[Doug.E.Fresh]

Anyone try the MXJO 35A 3000mAh 18650 batteries yet? I just ordered a pair. I'll let you know my opinion once they arrive.

 

[NemesisVaper]

Treat them as a 20A and you should be fine.

LG s new 3000mAh struggles at much over the 20A rating, so I can't see the MXJO being a true 35A capable cell, especially at 3000mAh. Either it'll falter at 35A, will loose a significant amount of capacity or most likely both.