Investigations
12 VOLT/24 VOLT BATTERY EQUALIZER ON BUS
NHTSA Preliminary Evaluation PE99075 - closed, opened 1999-12-08.
NHTSA investigation PE99075 is a Preliminary Evaluation opened on 1999-12-08 and currently closed. The subject is tracked inside the Office of Defects Investigation queue. Latest activity on this investigation was logged on 2000-05-31 - NHTSA updates that field whenever an Information Request goes out, a supplement is filed, or a status change is recorded in the public docket.
A Preliminary Evaluation like PE99075 is the entry point of the federal defect-investigation process. NHTSA engineers scan complaint databases, field reports, and manufacturer data to decide whether an Engineering Analysis is warranted, whether a voluntary recall is already sufficient, or whether the pattern does not rise to a defect finding.
Investigators summarized the matter as follows: "ODI has received information alleging failure of the equalizer on the vehicles listed above. An "equalizer" provides a 12 volt source from a 24 volt battery; in effect, two 12 volt batterier get equally charged in series..." Investigations are the early-warning layer of the federal auto-safety system, sitting upstream of formal recalls and defect orders. Whether this one closes without action or escalates into an Engineering Analysis, the full history stays in the ODI archive so researchers, litigators, and buyers can pull the paper trail at any time.
Investigation Summary
ODI has received information alleging failure of the equalizer on the vehicles listed above. An "equalizer" provides a 12 volt source from a 24 volt battery; in effect, two 12 volt batterier get equally charged in series from a 24 volt source, and equally discharged in parallel into a 12 volt load. The equalizing term refers to the distribution of charge and discharge energy between the two separte 12 volt batteries. When the failure occurs the equalizer smokes excessively, filling the bus with smoke. As these buses may be carrying 50 or more people, excessive smoking (with possibility of a fire) is a concern. A fire may also result. A preliminary evaluation is being opened to gauge the scope of the issue, the technical causes of the equalizer failures and to address the resulting public safety concerns.
About This Investigation Type
A Preliminary Evaluation (PE) is the first phase of NHTSA's investigation process. It is opened when the agency identifies a potential safety defect pattern, usually triggered by consumer complaints, manufacturer reports, or field monitoring. During a PE, NHTSA gathers information to determine whether a formal engineering analysis is warranted.
Data from NHTSA Office of Defects Investigation. Cross-references: NHTSA recall campaign API and NHTSA FARS where fatality records overlap. PlainCars does not rate or recommend vehicles. about how PlainCars sources NHTSA data.
Read our methodology - how this data is sourced, computed, and verified.