High Voltage Battery Test - Prius Hybrid et al.

High voltage battery testing is now available on all series-parallel hybrids: Toyota Prius, Camry, and Highlander; Ford Escape, Fusion, and their Mercury kin. By loading the battery to the margins of its normal operating conditions we can determine the current pack balance and strength.

The test is run using the car’s own operating paradigm; we do NOT use the Midtronics HYB (Hybrid Battery System Analyzer) for lack of proven performance in the field.

Cost: $50

Time: 30 minutes

“Trending” (the ability to predict failures) is the holy grail of EV testing and has become a hotbed for bullshit. Our test will tell you the current condition of the pack to anticipate near-term repairs and/or decide whether to sink a bunch of money on something else on the car. Beware of false promises or prognoses.

First pic: Failing HV battery; note climbing Delta SOC (green) as SOC (blue) plummets.

Second pic: Good battery (one of our rebuilds, tested before delivery); note Delta SOC (green) does not change as SOC (blue) goes down. Max/Min block voltage levels do not diverge.

Originally published July 26, 2010. Kept online as written, so the links that point here still work.