I have recently got a 2002 Focus 1.8TDCi which had the battery changed last September to a "standard" lead-acid type rather than what Ford state use which is a Lead-calcium type (Fords since 1997 i believe).
(not to mention it seem underrated for a 1.8 diesel, 510CCA when stock is 590CCA).

Is the use of a none calcium battery likely to cause problems and has anyone used a normal lead-acid none calcium battery on their Ford with no issues?

the smart charge can dump up to 18 volts into the battery, a "normal" battery won't like being charged the same as a calcium battery because it could lead to gassing and could go bang.

Ok, has there been any reports of this happening though?

The "normal" Lead-acid battery has been fitted to my Focus for 6 months.