My leisure batteries don't seem to last very long. After about 3 hours the lights are dim, and the water pump is struggling. I'm not doing anything particularly strenuous - just a couple of lights (conventional bulbs) on of an evening, ignitors on the hob for cooking dinner, bit of radio... The batteries seem to die very quickly. Any thing I can do to test their health at home (I keep a multimeter in the van for checking them)? I suspect they've been on the van for a ver long time, and are probably about tatered. how long would a healthy couple of batteries last me?