More details:
- year and how many miles
- how old is your 12v battery
- what is the charge % of the 12v battery (is it above/below 30%)
- original alternator and voltage when running
- any corrosion around battery
- any loose/corroded grounds in engine bay
- any issues with power drain if MDX sits for awhile
- any aftermarket parts
- any issues with driver's door switches (door harness), memory seat, door/hatch actuators, window functions, Bluetooth not working, factory alarm not working
- any problems with slow/weak starts before the message

 

If you have a voltmeter check the voltage of the battery while the cars is turned off and while it is on.
while off, a good battery is 12.2V and above - needs to be 12.5
While car is on and charging ~ 14V