Battery critical symbol warning on E92

[TX1]

Just got a 2006 e92 with the Nav pro installed.
Car came from a dealership, when installing the new navigation map I get the message that the battery is critical before I reboot the system. I read elsewhere that this is normal if am not mistaken as the upgrade needs lots of resources, is this right ?
My question is that if I do not turn the engine on and play about with the Nav or the stereo for about 30 seconds the message appears. Is this normal or is the battery on its way out ?
I have driven it for about 20 miles total these last couple of days on some decent stretches so I would have thought if the battery was low as was sitting at dealers it would have recharged.
Any opinions lads ? thanks.

[Remagel2507]

Be careful with messages like this - A mate had recently had his steering lock jam on his 2006 E92 and apparently it can be caused by low voltage to some modules.

He had to get a whole new column to solve the problem