You seem particularly determined to leave out the "constant" word when you say 20 amp max, any special reason? Constant drain is a whole different animal than pulse drain, once the masses realize that we might have less misinformation spread randomly for no reason.
Maximum continuous amp discharge data is what all the big battery manufacturers publish. Pulse ratings, if published, are as I understand it designed to be used for calculating motor start up max amps over time, and circuit fuse design. AFAIK all Li-ion batteries can be taken to twice the continuous amp discharge for some time period. The amount of time at a given amp number is rarely stated though and the number goes down as the battery ages and the internal resistance goes up. This is true for both continuous and pulse ratings. The continuous discharge can also be taken higher than the rating, but you will generally want to cool the batteries for this.
It's accepted that when we say a battery is a 20A battery we're talking about continuous discharge. If a supplier claims 35 or 40A for a 20A battery and does not specify "pulse", that's dangerous because someone could run it in a mod in pulses at 70-80A and the person would not know they are at four times the continuous rating. IMO the companies who market 35A and 40A 18650 batteries that are really 20A batts without specifying 'pulse' are only in it for a quick buck.
Then there are the other issues with running a battery at 2X continuous. This will very likely cause the battery to vent if the button stays on, plus as I said the safe pulse time period at X amps goes down as the battery degrades and also as ambient temperature rises. Yes, the number for continuous discharge goes down too, but if someone is running pulses at the continuous rating their batteries will take much more degradation and abuse before they have safety issues.
For me it's all about safety. People will push things and just see how it goes. Most of the time if things are not pushed too far they go well. However running at 2X continuous amp discharge with a battery that has seen 200 charge cycles, has always been discharged at 1X continuous and was recently discharged to 2.4V a few times and was once hard shorted for a couple of seconds is not something I would do because I consider it too much of a safety risk. So how do you qualify this, how do you explain it to people? I can't, there are just too many variables and conditions and not enough data to accurately quantify it all. However, not exceeding the continuous amp rating, people will vape about as safely as they can.
Now if someone wants to push their battery harder than this, that's their decision. Hopefully they understand the increased risks and what they need to do to mitigate that. But it's not something I can in good conscience tell people is a safe practice.
. From there I found the UL 1642 standard for Li-ion battery safety which I have never read before.
