We have seen reports of owners having issues with hybrid vehicles retaining sufficient battery charge. Using a trickle charger can help with this issue, as can putting the car into 'ready' mode for a period of time to allow the engine to feed charge back into the battery. It is not clear if this would be sufficient grounds to reject the vehicle, as it would need to be either not as described, of insufficient quality or not fit for purpose. You can read more information on this process here: www.honestjohn.co.uk/advice/car-buying-advice/how-.../ Some owners have fitted higher capacity batteries which have solved this problem, but this would be at your own expense and may forefit some elements of your vehicle warranty.