The battery in Evolve's Bamboo series GT just sucks. Surprisingly the rest of the board is great, however. With solid trucks and drive system, a clean, flexible enclosure and a beautiful deck it seems like such a waste to put such a shitty battery in there.
"But longhairedboy that seems like such a big battery, i heard is was 10S or something." Yes. Its a 10S1P 7ah (or 6.5) Li-ion prismatic pouch array with either a 10 or 11 lead balance lead depending on if the pack connects its negative to the the BMS pin 0 or not (some do, some don't) and 14 gauge mains. You read that right: they're inconsistent.
The problem with a pack like this is the complete lack of parrallel groups and cells that can handle high drain without resulting in terrible voltage sag. Using an 18650 based 10S4P pack made of quality cells with a decent discharge curve virtually eliminates voltage sag without doing any modifications to the ESC or programming whatsoever.
So far Ive used Samsung 25R and 30Q cells, LG HG2s, and Sony VTC5s. All are good quality cells, have an adequate discharge curve, and all drastically improve the performance of the Evolve Bamboo GT.
The only hang ups with this mod is you have to remove wood from the deck to keep it looking factory, and you need to be able to build 18650 packs. The original prismatic pouch is shorter than the 20mm you would normally allow for an 18650 cell plus heat shrink and balance leads. The new pack is too big to fit in the space the original pack fit in length wise as well. To resolve those issues, the BMS has to be moved on top of the ESC, the deck has to be modified by machining one rectangle out of the deck for the pack, and another slightly deeper rectangle out of the wood for the BMS.
The hang up part of that is that not everyone has an x-carve or other CNC to do this. It can totally be done with a standard router, though. All the x-carve is is a DeWalt 611 router with motor controlled X,Y and Z axis. So all you really need to do it is a regular router and maybe some kind of guide jig.
But then you still need to build an 18650 pack. Soldering these things can ruin cells if you haven't done it a lot or at least know what you are doing, and hardly anyone has a spot welder. The routing of the deck can be worked around, but building the new pack is beyond most people's DIY capabilities, or at least their comfort, i would think.
Thankfully I'm here to courageously void your warranty with reckless abandon in order to champion your desire to get much better range and hella less voltage sag. Cost of the service i'm providing is $350 and you bring your own cells. Normally i send people to liionwholesale.com for cells but you can get them wherever you like. Once i receive the cells and the board, turnaround time is about 2 days.