…and just by way of update, I just wired up the first one. Removed the internal battery (to make 100% sure the external was working) and fired up the KX2. All seems well. The only thing I messed up was making the wire slightly too long so it won’t fit internally.
That is fine though because I want to use it as an emergency swap out battery and also use it with my Venus SW3B, which I haven’t gotten on the air yet!
I got 2 x 3000mAh, 1 x 6000mAh and 1 x 8000mAh packs. Lovely jubbly!
Thanks again Fraser. 