You should have 13.25 volts on a good battery and it should not drop below 12 volts when cranking. If you have EFI you need at least 10 volts to run the brain. Get someone to do a load test on the battery after it has been on a charger a while. A good battery and altenator should put out between 14.25 volts and 15 volts with the engine reved to about 2K. I would get the battery checked first then the charging system. If there is nothing wrong then check the amp draw of the starter. Some times the groves in the armature get plugged with carbon from the brushes and short them out causing a high amperage draw.
