SXmini Q Class Powered by YiHi SX450 chip
- Thread starter JimScotty0
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Boost has nothing to do with it. You are limited to the power your batteries can supply period. All boards do is boost either the voltage or current while bucking the other one inversely. No board is 100% efficient so not only do they not create more power than is put into them (an impossibility per the laws of physics), there are actually losses.
An 18650 with a 20 amp constant current rating can supply a board 84 watts maximum (20 x 4.2). That's not even a realistic number since as soon as you attach the load you will get some voltage sag. Two 18650's will supply the board twice the amount of power (a theoretical best of 168 watts). These numbers decrease as the battery loses charge throughout the run.
I'm really getting frustrated with people claiming magic boards some how create power. I'm talking about just Yihi. I'm talking about any board made by anyone. It's simply impossible.
An 18650 with a 20 amp constant current rating can supply a board 84 watts maximum (20 x 4.2). That's not even a realistic number since as soon as you attach the load you will get some voltage sag. Two 18650's will supply the board twice the amount of power (a theoretical best of 168 watts). These numbers decrease as the battery loses charge throughout the run.
I'm really getting frustrated with people claiming magic boards some how create power. I'm talking about just Yihi. I'm talking about any board made by anyone. It's simply impossible.
Sorry Vlad, tI want it for the 350J-V2 but I found the link anyway! Cheers
steve
ps. I thought I was in the ML thread, not the 450Q...lol!
Yep that's why my point only went to designing the device to safely operate within the parameter's of the batteries. Why Not???
Boost certainly does have a roll if the device isn't designed for the output current. Without Boost 200W at 6V = 33.3A, With Boost 200W at 9.5V = 21.05A So no boost = much higher current requirements in the output circuitry. But your right in Boost has less importance than say limiting the input current by the design of the board to about 3/4th the battery continuous rating of (say 23A) when using a 30A battery.
And pretty sure 20A battery's won't be adequate or recommended for this or any other 200W device in dual configuration. You might try your math with say 30A, I'm pretty sure the recommended battery will be at least that.
Using your formula of max voltage and max continuous current with a 30A battery, 4.2*30= 126W, Times two = 252W potential. No magic in those numbers.
At any rate the topic and propaganda is irrelevant as we have no real information on this device specifications, what exactly "Maximum 200 Watt" means etc.. So to infer something is wrong or has been done wrong on this device is premature. Not to mention all other dual 200W devices that are already out in the market.
Yep this all is just discussion. At this point only hype about the Q device and the SX Pure atty. Keeps the "sheeple" interested.
I thought I was on holiday today
Woke up, see the light seeping through the edge of the curtains
Argh, big stretch, roll over, get comfy
Then the penny dropped, I was not on holiday just slept through my alarm $#1t
Except when the charge on those two 30amp cells drops to 3.3v (typically above cutoff limits), which will happen fast at 200watts. Than you are pulling just over 30amps. I'm not saying this is guaranteed to cause a failure, but it will stress the batteries. Also, there aren't a whole lot of real 30amp 18650s out there, but a crapton of falsely labeled 20amp or below cells that claim to be 30 or above. Put two of those in, and suddenly you are pulling 150% of the cdr, possibly without even knowing (and the mod has no way to know the cdr of your cells).
Also, I'm curious as to why you are using 9.5v or 6v in your math. An 18650 battery can only output 4.2v, and should not be drained past 3.2v. So, taking into account this is a dual battery mod, that gives a range of 6.4v to 8.4v. Meaning at 200watts you pull 24amps on fresh full charged cells (not accounting for efficiency), and 31.25amps at the typical cutoff voltage.
@SXmini posted this reply on Facebook about the Q and 200 watts:
As long as make sure the 35A battery, with 0.2ohm resistance, Voltage 6.32V, Current 31.62A, it can reach 200W for sure, we already tested it.
As long as make sure the 35A battery, with 0.2ohm resistance, Voltage 6.32V, Current 31.62A, it can reach 200W for sure, we already tested it.
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As I said the topic is really irrelevant since we have no information on the device, how it manages current draw, voltage, temp of cells etc... There's just no real information available to even discuss how or what it's doing at this point. The point was it's possible to do safely if designed for. And the reason I was discussing the 6V & 9.5V is because I know of a couple different boards one does Buck only the other does Buck/Boost and that's their max outputs. Probably shouldn't have talked about that as it just confuses the topic.
Ahh there is one mod that is 133 watts. I realize this is a YIHI thread. I just haven't seen the other 200 watt mods get so many replies saying the same thing that 2 18650s isn't safe in a 200 watt mod. This thread has 9 pages so far of almost everyone saying the same thing like it hasn't been posted a thousand times already. It just seemed strange to me. My guess is Vlad1 is right when he said:
I certainly don't give Yihi more flack. I've been equally critical of e.g. Joyetech. However, I've found that in this thread (and one of the wismec vaporflask trends, regarding the single-battery 100w Stout) there are many more who refuse to accept facts and are a bit too eager to defend their favourite device/manufacturer no matter what.
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You're probably right about that. I think people are beginning to expect inflated specs from less expensive mods. I don't however expect it from top of the line mods/chips like the SX, DNA200, Dicodes. Heck I have more mods with Yihi chips in them than any other company. I'm just disappointed that they seem to be letting the marketing department trump the engineering department when it came to putting out the spec's of the newest SX model. I would think I'm not the only one who would be a little disappointed by this turn of events. For them to release statements like use your 35 amp 18650 batteries is just embarrassing. No such beast exists. It's just marketing department BS.
Maybe this tech here will filter down to 18650's and venting batteries will be a thing of the past.
yeah, u might be right too. a high end device certainly deserve much more scrutiny. especially one that is on par with wat DNA fanboys owned.
so i guessed we both agreed that Yihi is getting more flack than others?
I think most people agree that using 2 18650 batteries at 200 watts seems unsafe but saying it over and over for 9 pages seems a little extreme to me.
It's repeated when someone claims otherwise (like Yihi having changed math for it to be safe) or says that it doesn't matter. And it really hasn't been repeated that often, and every time after the first as a response rather than an initiation.
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I think you need to reread the thread again. It gets repeated over and over even when no one claims otherwise. Maybe the people who are repeating whats been said a thousand times haven't read the thread. I know that happens a lot.
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