These instructions are meant to be a guide for Hybrid Automotive Prolong Battery System owners. Every hybrid battery is different and will exhibit its own unique charging and discharging patterns. Your experience may vary from what is listed below. We offer no guarantee that the below instructions will work exactly as described for your battery.

In order to recondition your hybrid battery, you will need a Prolong ‘Discharge Ready’ Battery Reconditioning Package (shown at right).  The Prolong ‘Standard’ Battery Charger does not support battery discharging. Visit our FAQ page to learn more about the difference between our  ‘Discharge Ready’ and ‘Standard’ Battery Charger systems.  You can view and order a Prolong ‘Discharge Ready’ Battery Reconditioning Package anytime via our online store located here.

Battery Reconditioning Overview:

NiMh Hybrid electric vehicle battery reconditioning consists of two primary elements: (1) charging/balancing the battery pack and (2) deep discharging the battery pack.  Battery reconditioning is combining the charging/balancing process and deep discharging process multiple times to recondition the battery.  This process will break down voltage depression within the battery cells restoring lost usable battery capacity and equalize the cell voltage levels to each other.  The ending result is a battery with more usable capacity for the vehicle to take advantage of.

We offer the Prolong Battery Charger (with harness) for charging & balancing the battery pack.  For deep discharging the battery, we offer both the Prolong Battery Discharger and simple light bulb discharger.  These items are combined in our Prolong Battery reconditioning packages.  We also offer the Prolong Module Load Tester to test individual battery modules and identify failed units.

  • To view detailed instructions for charging/balancing a battery with a Prolong Battery Charger: click here.
  • To view detailed instructions for deep discharging a battery with the Prolong Battery Discharger: click here
  • To view detailed instructions for deep discharging a battery with the light bulb discharger: click here.

Battery Reconditioning Step-by-step Process:

Note: While not required, we recommend disconnecting the 12V AUX battery to ensure it is not accidentally discharged by interior lights while performing the reconditioning process.

1) Charge the battery until the voltage stops rising. A full balancing is recommended, but is not required at this step.

2) Discharge the battery to at least 0.8V/cell.  Refer to this table for pack level voltage termination points.

3) Charge the battery again until the voltage stops rising.

4) Discharge the battery to 0.6V/cell.

5) Charge the battery again until the voltage stops rising.

6) Discharge the battery to 0.5V/cell.

5) Charge and balance the battery pack one last time.  Let the charger run for at least 4-6 hours after the voltage stops rising to ensure the pack is fully balanced.

6) Disconnect the charger and allow the battery to rest for at least 30 min (one hour is recommended) before attempting to start the vehicle.

The above process constitutes one battery reconditioning treatment.  If you are short on time, you can perform only two discharge cycles instead of three.  It is possible to complete a two-cycle reconditioning treatment over a single weekend if it is started Friday evening and finished Monday morning.

How to deal with failed modules (when reconditioning only does not work):

In the majority of cases, performing the above battery reconditioning treatment will be enough to restore battery performance.  Depending on the condition of the battery and how degraded it is when the reconditioning treatment is performed, a reconditioning treatment alone may not be enough.

If the battery does not recover from the initial reconditioning treatment and the failure errors return (red triangle or IMA light), then one or more modules inside of the battery has experienced a hard failure.  A hard failure cannot be repaired by reconditioning alone and physical replacement is required.

On a Honda hybrid battery, it is very difficult to replace a single stick and match the replacement IR levels and capacity to the remaining battery pack.  For this reason we do not recommend it – full battery replacement is the necessary course of action.  We recommend contacting Bumblebee Batteries for brand new, large capacity, high quality replacement IMA batteries.

For Toyota hybrids battery packs, the success rate of replacing only the failed modules is very high.  In order to identify the failed modules in a Toyota battery, a load test of each module must be performed.  Our Prolong™ Battery Module Load Tester is a simple, inexpensive way to identify and replace failed or failing battery modules.

After replacing the failed modules, a second battery reconditioning treatment should be performed.  This will allow the new module to equalize with the rest of the battery pack. After replacing the failed modules, regular maintenance of the battery with a Prolong Battery System should prevent additional modules from failing.