I use my JXD for track footage. I simply pop it on charge between sessions, so battery only needs to last 20 odd mins between charges (which is obviously no problem at all, they prolly last over an hour). But I also wired up a 5v fixed voltage regulator (~75p maplin) so it can be charged from the bikes battery. I did suffer some interference when filming connected to the bike/charging, I never looked into this any further but it might be something really simple.
Like I noticed the max input voltage was less than I was trying to put in with the bike running (i.e. the bike running is say 14v, max in for the voltage regulator was 12.5 or summin) .. I intended to actually just feed it from two regulators ... i.e. step it down to a fixed 9v, then to a fixed 5v ... the 9v can take upto 15 odd volts input you see
If you are going the JXD route, there is no point buying one of the higher spec cams (unless you intend to upgrade the recorder at some point).