Isuzu keeps things simple, which suits Dubai. The D-MAX pickup and mu-X SUV use a conventional sealed battery under the bonnet, and a new one does not need registering with a diagnostic tool. What matters is cranking power. A diesel has high compression and glow plugs, so it needs more starting current than a petrol engine of the same size. Fitting a smaller battery just because it sits in the tray is a common mistake.
Many Isuzus in Dubai are work vehicles. They carry tools, run beacons and chargers, and make dozens of short stops a day, which never gives the alternator time to top the battery up. Vibration and dust loosen the clamps as well. On the NPR and other light trucks, check the handbook first: many run a 24V system from two 12V batteries, and those should be replaced together as a matched pair.