corporate jet,for starters ,get the red top optima battery [starting battery] and a blue top [deepcycle] for your accessories like stereos and such.If you have an ammeter only on your dash to check charging ,get a volt meter as well.It should read above 12 volts [12.5V].You can buy a tester at most speedshops that plugs in your cigarette lighter socket .This equipment checks your alternator's output as well as the condition of your battery while you're running your engines.Your brushes in the alternator may have worn down ,or the built in regulator faltered ,causing insufficient charge.Hope this helped.