what 3.7v lipo
 

starting GT12 an really confused over what make of lipo to buy and how many

look on the brca list? I bought a cheap core rc one, no reason they shouldnt be rubbish.
2 should be enough

The higher the capacity and discharge rate (C) you can afford / want to spend.
They need to be hardcases.
Make sure they are on the BRCA Homoligation list if you intend to do BRCA sactioned events.
You could do with at least 2.

HTH
Wig

Which 1s LiPo
 

Yes quite a choice, I opted for the Intellect 7000mAh for my GT12 having used the 6000mAh a few years back in my 1/12.
Two runs per pack with plenty left in reserve using the Thunder Power 13.5T at 30 degrees advance on around 67mm/rev and the Hobbywing 1s esc on 'blinky'.
Never tried to get 3 runs though, I suspect you would notice some fall off in speed after 15 minutes total running!!!

These are getting good reviews from the 12th guys for both capacity and duration.

http://www.zen-racing.co.uk/catalog/...0mah-70c-p-929

Otherwise stick to the Trinity (Zen Racing) Reedy (CML Distribution) and CRC (AMC) packs - they are all good. HTH :)

Balls Out 1S lipo from MB models are the best I've run.
lots of top 12th, gt10 and gt12 guys use them.