The 3.7v battery in my Flightdeck is failing and since the company no longer supports it I need to have a 3rd party install a new battery. The original battery has dimensions of 3.6/139/135 but there is some space that can accommodate a slightly larger battery. I've been trying to find the biggest capacity I can add to it and so far all I see are 10000mh. Is that about as good as it'll get before getting too out of dimensions? I would just like some good recommendations for a reliable battery.