I bought a new battery for my Sony DCR-HC22E camcorder. The original battery works fine for about 80mins. However the new battery only lasts about the same time (or a bit less). The new battery reports 136 mins but switches off around 70/80 mins useage. I ran both batterys down and re-charged them but the new battery does not give 136 mins. Question do I need a battery charger for this new battery NP-FP50, rather than using the camera docking station as its a heavier duty battery? The original battery is a NP-FP30 and works fine. Any comments please.