BOSTON -- New cars on the Red and Orange lines are back in service Monday, the MBTA announced. The cars had beenafter an out-of-service car had a battery failure in the Wellington Yard on June 20.
All of the cars were removed from service as engineers worked to identify the cause of the problem.
"CRRC, the cars' maker, and the MBTA have worked collaboratively with both the battery and battery-charging system manufacturers to determine the root cause and appropriate corrective actions," the MBTA said Monday. "The cause of the problem has been identified as an out-of-range battery temperature reading, which caused the battery to overcharge for an extended duration and fail."
The agency said they've changed the design to increase airflow and modified the temperature sensing circuitry as the solution.
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