I have an 89 88 spl that runs great. Been having battery problems (only get a dozen starts out of a charged battery) recently. Figured the battery was old so I purchased a new one. Put in and it started right up. Ran for about an hour and threw anchor. After about 5 hrs I went to start the engine and it barely turned. Luckily I still had the old battery that I thought was dead and hooked it up. Same issue. I jiggled the trim lever and pop, it started! Got home and charged the newer one and it read 75% when I hooked it up. Any thoughts? Going to check voltage in the am at idle.