For what it's worth for folk building an electric 2x2.

I've had an issue with TP 6000 packs that actually caught fire in the model whilst in use. I've recently taken delivery of some new Flight Power - 6450mAh 5S3P F3A Pro Short packs. I managed to get out and fly last night and initial impressions are very good. Flew for around 8 minutes on the first flight with no noticable drop in performance. Packs were reasonably warm after a routine consisting of vertical climb-out, large loops, plenty of fast knife edge passes, knife edge harrier, some snap rolls. Didn't want to go too mad on first flight with brand new packs.

Two packs combine to make for a very compact installation. They can actually be installed with the length of the battery installed across the width of the fuselage and they are wide enough that they fit with space to spare between the two main formers. This makes installation really easy, just suspending the two packs underneath the two graphite tubes with elastic, just using the spare piece of composite board between the packs and the tubes to spread the mass more evenly. This really helps to get the C of G a little further forward as the entire pack sits in front of the rear former. An ideal pack for this model.

http://www.flightpower.co.uk/proddet...?prod=40536450

Phil