How to recondition your prius hybrid battery - Series 1

This post is to help those who wants to recondition their Series 1 Prius battery themselves. Do note that the series 1 Prius ( 1997 - 2000 ) refers to the model that uses the Nimh D cells. These were never imported into the United States. Those in the US will refer to the Series 2 ( 2000 - 2003 ) using the parametric Nimh cell module as the Series 1. ( Confused ? )

Caution : The Series 1 Prius battery pack consist of 240 Nimh D cells in series. Up to 360 volts could be exposed. Wear protective gloves when working with this battery at all times.

The first step is to remove the battery pack from the vehicle. You can refer to our website for more detail information. HERE

When we first started reconditioning this battery in 2007 we did what most people would do that is to check the condition of each tube with a volt meter and replace the weakest tubes with better ones. This process though logical is extremely frustrating. The problem is that each tube consist of 6 D cells in series and measuring the voltage of the whole tube does not accurately reflect on the condition of the tube. To more accurately check this remove the plastic wrapper and test the voltage of each D cell separately.

Whenever you try to determine the status of a cell by it's voltage you have to know the state of charge before you start your measurement. Using a suitable Nimh charger give the tube a full charge before you start your measurement.

To accurately determine the capacity of each tube discharge the tube with a know resistor and measure the amps used. If you get 5 amps and above the tube will be suitable for use in the pack.

When you get all 40 tubes, assemble the battery pack and with luck you have reconditioned your own battery pack successfully and your car will be roaring back to life again.