It is possible to dump a 5000mah 4S lipo in under fifteen minutes depending on track conditions.
Your best bet to make a guarenteed 15 minutes regardless of track conditions I have experienced is with a 6000mah 4S lipo. I have managed to dump these in 18minutes. They are heavier for sure, but nothing like running a 5S 5000mah pack or a porky 8000. I have no handling issues with this pack in an RCPD RC8 conversion.
I am not running a really hot setup either, a Neu 1512 2.5D combined with a Mamba Monster ESC. Timing set to lowest and about 20% punch control. I actually found I got better runtimes with more punch control to cut down on wheel spin. and I run 13.2V cutoff.
the PQ6000XP packs can be had for about $180 shipped from RC Lipos right now. You can also get them for about that price when you include shipping from hobbycity if you submit an offer on the battery pack.
Get two of these, and you can do a 30 minute main with 1 swap and also some warmup driving too.
Its pricey, but, in the grand scheme of things (basically 2 2S lipos for about $90 shipped, high quality), its not that bad.
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