Keep in mind it is quite possible that your battery was severly hurt when it ran down in the beginning. These batteries are not designed to be dropped below a certain percent of charge and if they do they never recover except for extremely short periods of time. Then again you may just have a bummer battery. If you have a good electrical shop in your area ( alternator/generator rebuilder) they should be able to load test the battery. Actually they are not that expensive to buy a new one, keep the receipt and if it goes out you can always take it back. Beginning to sound like a battery that has been run down to far, many lesser expensive auto batteries will do the same thing, NO battery likes to be taken all the way down..it will kill them. Keep us posted