Low resistance cartomizers on KR808 - Fact or Dogma?

[Death Lobster]

I often read advice on these forums that one should never use low resistance (~2.0 Ohm) cartomizers on a KR808D-1 battery, such as a V2 or a Volt, as they'll destroy the battery. There seems to be much speculation that those poor wittle itsy-bitsy batteries just can't take the heat! Poor little fella'. Regardless of what the manufacturers say - if they say anything besides "use our cartos or else" - this comes down to a pretty straightforward calculation.

Any e-cig in this class will (and should, unless the manufacturer is incompetent) contain a lithium-polymer battery. These batteries are currently about at the forefront of battery technology with regard to energy density and, more importantly IMHO for an e-cig, power density.

Ostensibly, you should not use low resistance cartomizers in a cig-a-like because they will damage the battery. This is often said by those who use much larger devices. I understand the apparent stigma of "big battery = BIG POWER." That is technically true. But let's get real. Nobody is putting 50 Watts through their PV when they vape. The only way to damage a LiPo battery in the context of this application is to pull too much current from it. So let's do a quick analysis.

LiPo batteries - properly charged - top out at 4.2 Volts. Assuming a low resistance 2.0 Ohm cartomizer and nothing else in the way, you will pull 4.2/2.0 = 2.1 Amps. That is worst case, at the highest voltage the battery will reach and that is also assuming there is no voltage drop under load. This is really not *that* much. 8.8 Watts.

I have a few batteries I pulled out of Blu disposables. They are lithium-polymer batteries rated at 270 mAh, with a maximum safe discharge of 15C - 0.270A * 15 = 4.05 Amps. A 15C discharge rate is about the middle of the road when it comes to high discharge LiPo batteries. The Volt/V2 standard batteries are a bit smaller but not much. According to the V2 website the standard 110mm battery is 250mAh. Going back to our maximum possible current draw of 2.1 Amps, that equates to a discharge rate of 2.1 Amps / 0.250mAh = 8.4C.

This battery would therefore be damaged using a low resistance cartomizer if the maximum safe discharge of the battery is less than 8.4C. I find this unlikely - that would be silly of V2 to use such a battery.

So, what is the maximum safe discharge of a V2/Volt/similar KR808D-1 battery? I am willing to bet that it is considerably higher than this - it would be stupid of such a manufacturer not to use high discharge batteries in this kind of product.

There is of course another possibility. If there is any other circuitry between the battery and the cartomizer that cannot handle the current draw it may be damaged by the excess, particularly if the battery is regulated. From a practical perspective, this is only a difference of 0.7 Amps - 1.4 Amps w/ a 3.0 Ohm cart, 2.1 Amps w/ a 2.0 Ohm cart. I again would be surprised if this relatively small difference at such a low voltage would damage this circuitry. For pennies you can cram far more power than that through an IC that would easily fit inside an e-cig. Of course without pulling one apart I can't say for sure. Once I have a battery that dies I'd be happy to do so. I doubt we can get a straight answer from any manufacturer that isn't a generic "cover-your-..." response.

Now we get to the point. Has anyone actually researched, tested, or otherwise interacted with these components that can answer these questions? Does anyone have any definitive data on these points? I feel like the whole "low resistance cartomizers will kill your cig-a-like, get an eGo/Provari/etc..." is just another talking point of those who subscribe to the "MY BATTERY BIG! BIG BATTERY BETTER. GRRARR" camp.

Does anyone have definite, non-speculative, non "common sense" information to back up the claims that these cartomizers are dangerous on KR808s? Or is it time to stop holding this imagined power-deficiency against them? Food for thought, I hope.

 

[Death Lobster]

Could a mod please move this to the KR808D-1 forum? I think it would be more appropriate there.

 

[T41CK]

just cut and paste it quick

 

[Death Lobster]

Suppose I could, just don't want to clutter the forum with duplicate threads.

 

[Johnnie Price]

Someone has already done this. Here is the thread.

Looking at it, there should be no problem using a 1.8 or 2.0 ohm carto/atty on a regulated 3.7 battery. I haven't tried it, because I actually like a cool vape.

 

[Caridwen]

Moved at OP's request.

 

[betterBquietnow]

I used smoktech ultra lr (1.3-1.5) cartos on my kr808d's w/ a 510 adapter before i got a proper pv because i didnt have a good source for 808 cartos. at the time, i thought heck if it ruins the battery oh well, they are fairly cheap anyway. my batteries were fine, and although i did this for only about 2 weeks (then got a p+10440) i never noticed a difference in battery life or had a battery die. i used this on both a sealed auto battery and a manual battery.

for xmas i got my mom and brothers starter kits from V2 because im hoping the cig-alikes will be more appealing to them and get them started on making the switch from smoking to vaping. in case they dont like whatever flavor they get from V2, im bringing a load of smoktech shorty's and 510 adapters and an arsenal of juice, hoping i can find them something they will fall in love with. im not expecting any problems using the LR cartos.

Here's my thing though -- if there were really NO harm in using LR cartos on these batts, dont you think the manufacturers would offer them? it wouldnt be hard to make kr808D cartos with a lower resitance, and would provide a warmer, fuller vape which can be key to those looking for a cig replacement. my thought is that if manufactureres are not doing this, they have a reason. i suppose LR's will run a tiny battery's life down in a heartbeat and thats a big turn-off, but i would assume they would still offer them if they didn't actually harm the battery's overall lifespan.

in short, im guessing that LRs do have a real effect, im just saying i haven't personally experienced it, nor do i worry about it considering the batteries are fairly cheap and the improvement in the vape (for my tastes) was very substantial. that being said, if everyone's xmas present dies quickly after i start mixing it up with smoktek shorty's, ill eat my words

 

[dale1962]

I have used 1.7-2.0 carts on 808,510 for years because I like a stronger vape than a 2.5ohm can give me...with that said I'm sure it probably effects longevity of batts but worth it to me.I still get 3-6 months out of most batts which is good enough IMO.Now I do rotate thru 4 batts a day.

 

[Johnnie Price]

They do make LR 901 atty's, and I think I've encountered some LR cartomizers from Kanger out in the wild.

V4L sells 2.0, 2.5 and 3.4 cartos. Now that I know that, I may grab some of the 3.4 for my next order of blanks.

I think the biggest reason we don't see more LR 2.0 cartos is because the majority of 808 devices are rebranded, i.e. Volt, Vapor King, V2, ect. The majority of 510 stuff out there doesn't appear to be rebranded, being resold straight from China. Just a guess this may have something to do with it.

 

[Death Lobster]

I'm not sure why a lot of manufacturers don't offer them, but consider the manufacturers who happily sell cartos that perform poorly despite there clearly being better options for them. SafeCig Micro, Stog, dozens of others. It may just be one of those things, this is how we started doing it and that's how we'll continue to do it.

I actually have some V4L WOW Vapor carts that are roughly 2.5 as you said Johnnie. However I found that for whatever reason they still perfom much worse than even 3.0 Ohm Boges or Kangers. Atomizer design I suppose. YMMV as usual; I tested them with samples from HHV and Halo.

 

[Johnnie Price]

Are they top or horizontal coil? I'm only interested for the cooler vape, but I can get that with my S.I. cartos and a VV.

 

[Death Lobster]

The Kangers I believe are horizontal, the Boges are a vertical coil. Both seem to perform really well but I'm digging the Kangers right now. Strangely I get a burnt taste using them on the V4L Vapor King. Never on the Volt or V2. I suppose that points to the latter batteries being regulated.

The regular Volt cartos are quite good as well.

 

[Johnnie Price]

I meant the V4L carts. if they're not bottom coil then I won't bother, because the S.I. cartos rock.

 

[Death Lobster]

I'm happy to pull one apart for you, I've got a couple dozen of them that I probably won't use. I'll reply when I get to it.

 

[Death Lobster]

Ok that didn't take long. I probably didn't have to actually disassemble them to check but I've got more cartos than I know what to do with. I've got a Cool Cart here and a WOW Vapor cart, both look to be vertical coils.

 

[Johnnie Price]

Thanks for that. It'd be nice to have the higher ohms, but it's not worth it. I'll just stick with S.I. if I ever buy another cartomizer.

 

[ajventi]

I haven't filled one up and used it yet, but I picked up these 1.6-ohm 808 DC Cartos from Madvapes.

From what I understand it affects overall battery lifetime, even if you're below the C rating. So It's not so much that it's going to fry your battery, it's more of a case that your battery might only last you 3 months before it won't hold a charge any longer. I don't have a mini volt, although I'm planning on eventually getting some, but it's possible the voltage regulator might drop the voltage once you reach a maximum power.

Also I think LiPo is generally a 3-V, not 3.7-V battery. So if it is a 3-V LiPo, and it's being boosted to 3.4-V (or 3.7-V) the actual amperage the battery is seeing is going to be higher than the current @ the boosted voltage.

 

[Death Lobster]

The nominal voltage is 3.7 V. LiPo batteries typically have a charged voltage of 4.2 Volts - that's just the chemistry of the batteries, large or small. You can discharge them to 3.0 V without damage - my standalone battery charger will take them down to this voltage for a discharge cycle. Going any lower is not recommended and can damage the battery, generally you wouldn't want to go down to 3.0 V in normal use.

A regulator that maintains 3.7 Volts would initially have to step down the voltage, then boost it as the battery discharges below 3.7 V.

My V2 standard battery right off the charger is around 4.4V, which is way too high. Assuming that this is the actual voltage of the cell, it is dangerous and will lead to much shorter battery life. If this is a common practice, perhaps this is why so many e-cig batteries seem to die prematurely. I am going to take apart both the V2 and the Volt chargers and have a look inside, and also monitor the charging to see if they have "proper" LiPo charging cycles.

The V2 has a tendency to periodically flash from red to blue and back as the battery nears a full charge. To me this indicates "dumb" charging circuitry that only charges in constant-current mode and stops when the appropriate voltage is reached. If that is indeed the case, then ~30% of the battery's capacity remains unused. That sort of thing would be a big problem on a small battery and I'd be surprised if manufacturers are truly OK with it. Considering a proper LiPo charging IC can be bought for nickels in large quantities, it will be interesting to find out. I'll save that for another thread though.

Just checked it again right off the charger: 4.2 Volts. Last night it read 4.4 V. Perhaps a faulty charger is to blame.

 

[Death Lobster]

Looks like my suspicions are confirmed. The Volt 65mm battery is supposedly 220 mAh. I charged it fully with the USB charger (light turned solid blue) and connected it to my desktop LiPo charger. I connected the charger directly to the battery by removing the ash cap and attaching micro hooks to the battery wires.

I then put it in discharge mode at 0.1 Amps (discharge to 3.0V). Once it was finished, the charger reported that it had drained 175 mAh of capacity. I then set it to charge, again at 0.1 Amps. At the end of the charge, it reported a charge of 210 mAh.

Neither the V2 or the Volt USB chargers seem to have proper LiPo charging circuits. I haven't found the datasheet for the V2 charger IC yet, but the one in the volt contains a dual comparator chip and a few resistors. More investigation will be required but from an initial glance it does indeed look like the USB charger will charge the batteries to 4.2V and stop. Thus leaving - in the case of the Volt - 35 mAh of the capacity unused (17%).

It's still too early to make a definitive judgment but from the looks of it thus far, a lot of the e-cig manufacturers are going to have some explaining to do considering many use common components.

And how much does a proper LiPo charging chip cost?
MCP73831T-2ACI/OT Microchip Technology | Mouser

0.42 cents per reel of 3,000. This is how much expense Smokeless Image - so far - is unwilling to spend for an extra 17% of battery life out of each e-cig.

 

[ajventi]

You have successfully knocked yourself OT.

It's like Li Battery 101 ... Charging to full charge is a bad idea and leads to reduced battery life. For the entry level product you're analyzing here. I'd say it's pretty freaking obvious they want their consumers to not be ...... off by the fact that their batteries stop functioning 3 months after they buy them.

They are not marketing their products to you who want to use LR equipment. They are marketing their batteries to the entry level vapers. As I said before you should be smart enough to realize if you want to use LR stuff on their batteries you are probably willing to sacrafice (possibly) months of overall battery life for you higher quality vape.