As the population of hybrids ages, more people are experiencing hybrid battery (also known as the traction battery) failure due to cell variance, internal terminal corrosion, or as a result of overheating due to a clogged or failed fan.  Once the battery failure has been diagnosed the owner must decide what kind of replacement battery they want, factory new or rebuilt.  What are the pros and cons of each?

A rebuilt battery comes assembled as an entire unit – all of the cells, internal wiring and buses, high voltage relays and battery control computer are installed in the case –  and is ready to be put in the vehicle.  These units originate from scrapyards or as core returns on previous rebuilds.  The rebuilder identifies the failed component, replaces or repairs it, and resells the battery as an entire assembly.  The technician receives the assembly and installs it in place of the owner’s failed unit without any further dis-assembly or internal inspection.  The used unit is returned to the rebuilding in the re-builder’s provided packaging.

A factory new battery comes as a new case with pre-installed factory new cells.  The technician removes and disassembles the failed unit, inspects and swaps over all the internal modules, relays and wiring to the new case and installs the battery back in the vehicle.  Batteries without excessive internal corrosion or leaking cell electrolyte are packaged in Toyota’s proprietary case and returned as cores for recycling.  Batteries that are designated as hazardous due to water intrusion, cell electrolyte leakage, or obvious damage are reclaimed by a hazardous waste disposal company and forfeit Toyota’s core charge.

1st generation Prius battery

1st generation Prius battery

The pros of rebuilt batteries are numerous: rebuilt batteries are several hundred dollars cheaper than their new counterpart, are less labor intensive when installed and are readily available from local suppliers.

The cons of a rebuilt battery are also numerous: the majority of the internal components are used and are more likely to fail, cell electrolyte leakage due to mishandling is more common, components internal to the battery (especially the battery control module) frequently do not have the most updated software and the batteries are often shipped in unsafe ways.

The pros of a new battery include better reliability, safer handling and environmental procedures and better overall quality.

The main con of a new battery is cost – a new battery is several hundred dollars more expensive and is more labor intensive, requiring more hybrid technical training and safety training in addition to more labor.

CARspec recommends Toyota factory new batteries for all applications.  Because the age of the cells in rebuilt batteries can be 10-15 years old, we feel the overall risk of repeated failures is too high to make the cost savings worth the risk.