30Qs are actually under-rated by Samsung - which is bloody weird but has been confirmed in independent tests. And obviously they are configured as 5P in the pack so have a higher discharge capacity than a 1P config
appreciate you passing on the info to your friend - thanks man!
I mean you are talking to Battery jesus
Usually I give 30Q a 10-12A discharge per cell when I set up boards
I am sure this is not new info to many and not trying to âteach grandma to suck eggsâ, but hopefully useful to any non-deity reading the post
Of course.
A 5P pack of 15A cells would be rated at 75A. 
âUnder-ratedâ as measured how? Samsung rates them exactly where they want them to be rated for the claimed cycle life and desired performance. 30Qâs can, of course, be used at above their rating. This is true of any cell. But thatâs a capability, not a rating or indication of the cell being under-rated.
At 15A continuous a 30Q in free air will reach almost 70°C. Inside a wrapped-up pack, with hot cells next to it, the cells will easily exceed their 75°C max temp rating. At 16A (80A rating / 5) you are toasting those cells. That increases the risks of using those cells and shortens their life.
You might be thinking âbut no one does that, no one uses a cell continuously until it gets that hotâ. But thatâs what a rating is for, what it tells you. It says how hard you can run the cells without that kind of overheating (if in open air).
If a company rates the pack it doesnât matter whether we will use the pack that way or not. Whatâs important is the legitimacy of the rating.
The 30Q is a good cell and can be used hard. But at above 12A or so the voltage sag starts becoming disproportionately large and performance really starts to suffer when compared to true âpowerâ cells like the P26A, VTC5A or VTC5D, etc. This is true for pulsed or continuous use.
Put together the performance hit at higher current levels and the heating the cells see in a pack and, personally, I am troubled by a pack rating that is above the rating given by the manufacturer for the cells.
I do understand the extraordinary pressure these companies feel to rate their packs as high as possible though. The competition is insane. Thatâs the reason, certainly, for high ratings but it can never be accepted as a valid excuse.
75A also seems very optimistic for the gauge of wire selected for the main leads. The insulation might not melt at 75A but the power losses will not be small.
A final concern for the pack assemblerâŚsetting a pack rating that results in being over the manufacturerâs rating for each cell opens up the pack assemblers to some serious legal liability if there is an accident. This isnât an issue for a company in China (no one can touch them) but would be something avoided by any company in the EU or US. Any accident with the pack and the courts would slam them once the high rating was mentioned.
I donât say any of this to put down this pack or dissuade anyone from buying the pack. Iâve already told two people about it who might be interested. What the manufacturer rates the pack is a number, not affecting the quality of the pack assembly or its performance.
But we have to be careful about what we call a âratingâ, the differences between a rating and just a capability, and how we can safely use a pack and have great performance with long cell life.
lots of re-sellers (i.e. fogstar who I seem to remember as having a good reputation) rate them at 20A. a quick search of this forum using â30q 20aâ will also return a lot of results. but I am happy to be corrected 
I have also seen tests where they rate them at 20A discharge - but I didnât bookmark any links.
some graphs i found on page 1 of google for interest:
but not going to argue - itâs much better to keep lower discharge rates for all the reasons you stated.
Iâm not claiming anything on the specs of the cells - because I havenât done these sorts of tests on the cells under lab conditions.
in fact I am gonna edit the post and drop the discharge to 70 amps to make sure I am not over-stating anything
The 30Q page on the lygte web site rates the 30Q at 15A continuous.
There is a 20A graph but that demonstrates its performance at 20A. It doesnât mean it is rated at 20A continuous. It can be run at 20A as long as long as you stop before the cell reaches 75°C but thatâs not a continuous rating.
This is all very mixed up in what rating weâre actually discussing, continuous vs âburstâ, and how those relate to the âI wonât explodeâ capabilities of the cell. Youâll see vendor web sites used the highest rating they can, 20A, without explaining what it means. Thatâs not inherently dangerous but it makes comparing cells confusing and leads to lower performance.
Good talking to you about all this though and hoping you can sell the pack quickly!
Just to add additional data for consideration, here is Samsungâs rating for the cellâŚ.
I always love a good chat about things like this, thanks for your input Itâs great to learn new stuff and always good to correct any assumptions I have been under that are in fact not quite right.
Appreciate you man, and love having debates with folks such as yourself who are good fun/nice and avoid the âkeyboard warriorâ style of posting. Which is usually the case when they actually know what they are talking about 
Heâs one of the good guys.
Stick the dims of the battery on the listing you plum. Someone might be able to find an enclosure to stick it in then.
Hope youâre good man, catch you in the sunshine.
how very dare you sir! I identify as a satsuma these days 
for sure ! you down in London any time in the next few months? First round is on me
Guiltily just norf of Lahndahn now. But off tomorrow to pack to go to France for a bit. Will likely be around late April/early May.
sweet - see you in a few weeks then! have fun in France.
