I have a SJ111 3219. Batteries would not hold a charge. Charger is charging at 18 amps. Replaced batteries. Ran fine for 1 day. Charged overnight. Now will only run for a few minutes. Amp clamped the pack with raising the lift and it is pulling 150 amps under load. Under load the pack drops from 25.5v to 23v. What could be causing this? I can't find in the specs in the service manual anything about high amps.