MX-5ND2 "Battery Management System Malfunction"

[CeramicMX5ND2]

Was just leaving to get my weekly shop from Aldi. and I got the above warning come up.. Mazda Dealership is next to Aldi, so dropped in for advise- Went to show the advisor the warning and it had cleared! He told me my o/s reversing light wasn't working though, which was interesting because I believe it only has one fitted to the n/s...! Back to the original point - Is the warning just a fancy way of saying "Battery Low"? Should I just give the car a good run or buy a trickle charger like a CTEK? (Car isn't used daily so battery drain is inevitable especially during the winter months....!)

[CeramicMX5ND2]

I got a CTEK MXS 5.0 and have used it once - So far so good.. Seems to be a great little charger that goes through 8 processes of conditioning/charging.