EZGO controller problem

[SheilaC]

We have a 96 electric ezgo. About two months ago, we were riding it and it just stopped in the middle of the road. No warning, just stopped dead. My husband changed the solenoid and still didn't work. Had one repair shop look at it and they said it was a bad motor, just need to get a new golf cart. Sent it to a second repair shop and after six weeks of troubleshooting he determined that it was a bad motor and controller. Replaced both and we got it back last week. We did replace the motor with a more powerful one in order to gain some speed but he assured us that the controller was compatible with that particular motor and it would not be an issue. We rode it for nine days and on Sunday it stopped dead in the road again. Guy picked it up yesterday and brought it back a few hours later. He said he replaced the controller again and that it had blown up due to "weak" batteries. He said that he will not honor the warranty on the controller again if we don't replace the batteries. We bought our batteries in May and when my husband load tested them they showed good. The person we bought the batteries from said that he had never heard of weak batteries blowing up a controller. We do have a warranty on the batteries but they will not replace them if they test good. We are between a rock and a hard place. Has anyone heard of weak batteries blowing up a controller? Is it possible that the motor is indeed too strong for the controller?