The model is definitely Powervamp Racing 25, leading me to think it is a few years old. The 20 hour aH is given as 18, whilst the cranking torque is 680, way below the batteries in the Odyssey spec sheet. The batter measures 180mm long by 170mm high by 80mm thick, which does not tally with any of the currently listed batteries. The latter figure might explain the slow initial cranking, which speeds up once the engine is turning. I think in all probability the battery is marginal for an 1800cc engine.