Don’t want to deal with the hassle of the manual discharge process?
Check out our new fully automated Prolong Battery Discharger

 

DISCLAIMERS:

  • These instructions are meant to be a guide for Prolong Battery Systems owners. These instructions should not be used for any other product or purpose that what is explicitly stated herein.
  • Failing to follow the instructions as stated may damage your vehicle and/or hybrid battery.
  • Every hybrid battery is different and will exhibit its own unique discharging patterns. Your experience may vary from what is listed below.
  • The discharger meter should only be set one or two clicks counter clockwise from center (DC Volts). Other settings will pass current through and blow the fuse on the car harness!
  • The red and black wires that connect to the meter are charged when the Discharger is connected to the battery! Do not touch them together or to your body!!


Operational Overview:

The above graph of a 2005 Prius battery reconditioning is a great illustration of what to expect during the discharge process. Note how the green “After – Voltage” line drops quickly at first (0-30 min), this is the ~80%-100% state of charge (SOC) that is above the vehicle’s normal operating range. These battery was just charged & balanced with a Prolong Battery Charger and the top charge is quickly leaving the pack. Once the top charge has been extracted from the battery, the voltage flattens out for a long period of time (from ~0:30 to ~3:24). This is the ‘normal operating range’ of the battery, or around 80%-20% SOC. During these first two phases of the discharge process, the load (light bulb wattage) on the battery does not matter. The battery regularly sees 50A and higher, so the ~1.5-3A delivered by using 200W bulbs in the discharger is safe.

Once the battery reaches “empty” (around the 3:24 time marker, or ~20% SOC) the rate of voltage drop begins to accelerate rapidly. This is what usually tricks people!! If you are not keeping an eye the voltage as is reaches the end of its charge, you can miss the first light bulb change threshold. Play close attention to the voltage levels as you near this stage of the discharge process. It is during this deep discharge phase that the load on the battery becomes important and smaller wattage bulbs should be used. By reducing the load on the battery pack you will (1) minimize the chances of cell damage from polarity reversal and (2) obtain a more complete cell discharge.

Safety Precautions:

  • When using the light bulb discharger, you MUST connect the light bulb discharger to the car harness before installing the light bulbs.  When finished discharging, you MUST remove the bulbs before disconnecting the harness.  Connector damage will happen if this process it not followed!
  • You should fully charge & balance the battery pack before any discharge session. This will ensure the cells will be balanced when beginning the process.
  • Between each discharge cycle, the battery should be charged until the voltage stops rising.
  • Immediately after the final deep discharge cycle is finished another full charge & balance session should be performed on the battery.
  • The primary risk when using any simple discharger is over-discharging the battery at too high of a load. The voltage will plateau in the normal operating range for a long time as the pack drains. Once the pack reaches the bottom of the normal operating range, the voltage drop will accelerate and can be VERY FAST  Be sure to pay attention during this phase! (see above Operational Overview for more info)
  • You must use incandescent light bulbs. CFL/LED bulbs do not have enough load and will not work for this process.

Discharge Instructions:

Refer to the Battery Reconditioning Overview for a summary of the hybrid battery reconditioning process.  These instruction focus specifically on the battery discharge cycle.

When using the light bulb discharger, you MUST connect the light bulb discharger to the car harness before installing the light bulbs.  When finished discharging, you MUST remove the bulbs before disconnecting the harness.  Connector damage will happen if this process it not followed!

There are two things that require attention during the discharge process (1) When to change bulbs to reduce the load on the battery pack, and (2) when to disconnect the discharger and terminate the process.  These values vary depending on the vehicle type and hybrid battery size.  Please review the below tables for both of these important values for your vehicle.

The car should be turned off while discharging. While not required, we recommend disconnecting the 12V AUX battery to ensure it is not accidentally discharged by interior lights while the discharge is occurring. The discharge process begins after finishing an initial charge/balance cycle.  Disconnect your charger and connect the discharger. Turn on the volt meter by rotating the selection handle either one or two clicks counter clockwise.

To begin discharging, use the recommended wattage light bulb that corresponds to your vehicle and current battery voltage.  Install the light bulb into the base to begin the process.  When the battery voltage reaches the minimum value for that wattage bulb, unscrew the bulb and replace with the next lower wattage bulb. Repeat this until you reach the desired termination voltage. At that point unscrew the bulb and immediately reconnect your Prolong Battery Charger. If you accidentally discharge too far, it’s OK, the batteries are actually very durable and should recover without issue.

Note: Starting with the higher wattage bulb’s will shorten the overall discharge process. If you have the time and desire, it is fine to only a 25W bulb for the entire discharge process, but it will take 4-6 days to drain the battery to empty. Starting with higher wattage bulbs and stepping the load down accelerates the process such that the discharge can be completed in a single day (approx 6-12 hours depending on battery condition).

Discharge Termination Voltage Table:

Recommended vehicle specific discharge termination voltage:

**Approximate
Value**
Single Cell99-03 Prius04-15 Prius06-15 Camry Hybrid

12-20 PriusC (Aqua)

00-06 Insight

03-05 Civic Hybrid

05-07 Accord Hybrid

06-11 Civic Hybrid09-14 Insight

06-13 Highlander Hybrid

Chevy Silverado/ Tahoe Hybrid

Lexus RX/
GS Hybrids

Number of cells in battery packOne22816820412013284240
First Discharge0.8V182V134V163V96V105V67V192V
Second Discharge0.6V137V101V123V72V79V51V144V
Third Discharge0.5V114V84V102V60V66V42V120V

Light Bulb Wattage Change Table:

NOTE: The bulb wattage listed is the same for both the single bulb and dual bulb dischargers.  For example, if 75W is listed and you have a dual bulb discharger, a pair of 75W bulbs should be used to achieve the specified load.

Also, if you live in a country that uses 220V AC mains, all bulb wattages listed below need to be doubled.

Recommended vehicle specific discharge voltage change thresholds:

**Approximate
Value**
(110V AC mains)
Single Cell99-03 Prius04-15 Prius06-15 Camry Hybrid

00-06 Insight

03-05 Civic Hybrid

05-07 Accord Hybrid

06-11 Civic Hybrid09-14 Insight

06-13 Highlander Hybrid

Chevy Silverado/ Tahoe Hybrid

Lexus RX/
GS Hybrids

Number of cells in battery packOne22816820412013284240
Approx. Normal Operating Range1.2-1.4V274-319V202-235V245-285V144-168V158-185V101-118V288-336V
Toyota: 200W Bulbs
Honda: 150W Bulb
Approx. Minimum Voltage
1.17V266V196V239V140V154V98V280V
75W Light Bulbs
Approx. Minimum Voltage
0.83V190V140V169V100V110V70V200V
25W Light BulbsBelow
0.83V
Below
190V
Below
140V
Below
169V
Below
100V
Below
110V
Below
70V
Below
200V

Prolong Battery Charger User Guide