Starting problems on M813

[texas-5-ton]

I have noticed the past several times starting the 5 ton that it is getting harder and harder to start. Finally, it didn't start and the started started clicking like a battery problem. So I seperated the two batteries (4D's) and charged them up. Cranked like a brand new truck for several times then same problems again. The batteries are only 12 months old and when i checked the water in them, they were both low. so i have added water and they are on the charger again. The alternator is showing to be charging and might actually be overcharging just a tad. Other than this, it is all i have done to it. I was going to put a load tester on the batteries and check them tonight. Can you guys think of anything that might be causing this ??

The batteries are continental brand batteries and with them being 12 months old, i am not sure if they still have warranty. Also, any tips and prices on a NEW alternator??


Thanks