With the invention of the Power Jockey fixing the battery pack is made much easier. Battery failure is caused by the weakest cell falling below it’s operational threshold. The Power Jockey enables cells of wider capacity difference to be used.
Removing Battery Box From The Prius
TLocated between the back seat and the car boot. After removing the back seat. The black cover can be left on or removed. Remove the screw mounts behind the seat and in the boot. Remove battery through the door.
Remove Battery Packs from Battery Box
1) Shows the battery box removed from the vehicle. Battery computer on right side
2) Remove Circuit breaker – The orange handle unit is the circuit breaker. Unplug this before proceeding. This controls the power to the car. Dc in the battery box is still live and can deliver 340 volts. Be very careful. Wear gloves for protection.
3) Remove Battery Computer – Uncrew the computer from the pack unit and unplug the unit. There are three white connector plugs at the rear and one orange connector to the side. Depress the catch and ease it out carefully. Do not break the wires as they will be hard to reconnect. The smaller power plug to the left should be unplug as well.
4) Remove Battery Fan Unit – The fan unit is held down by 4 screws to the battery box. Remove the heat sensor unit and unscrew the fan unit. Pull towards you. May be a little sticky.
5) Remove Circuit Board – This is the most dangerous and tricky area. Make sure you have rubber gloves on. No 1 and no 3 cables are connected. No 2 and no 4 are connected as well. Isolate these cables from each other as well as you can. Remove screws and nuts as shown in the videp. There is a central screw in the middle that attaches the circuit board to the battery pack. Unplug all plugs and connectors. Note that 2 cables are attached to no 1 and no 2 terminals.
6) Remove Battery Mounting Screws – The battery packs are secured by 4 screws at the bottom unscrew them. You do not need to remove the base plate.
7) Remove Battery Mounting Screw Inside – The battery pack are secured by 4 screws on the inside unscrew these.
Remove Battery Connector – Disconnect the cable connecting the packs together as shown in the video.
Take great care not to electrocute yourself. ( DC current grabs you unlike AC). Tilt the box slightly to let the battery fall out if neccessary.
You will now be able to work on the batteries
Exposing Nimh Battery Tubes
1) Side Panels – Each pack has two orange side panels. There is a red pack identified by the red cables to the little white plug and a black pack identified by the black cables to a similar white plug. The outside panels have the two connector plugs. Make a note of these.
2) Black pack temperature control side – One side of the pack contains the wires for the thermo couples or temperature sensors. There are 4 in each pack middle row no 1,3.5.7.
3) Remove Sensor Screws – The screws connects the battery to the computer voltage sensors. Unscrew them but do not lose any as they are quite small.
4) Remove Nut – Remove the no 10 metric nut screws connecting the tubes in series. Be careful of high voltage. Not as dangerous here as in the circuit board above. Leave the plastic cover on one side on if possible to prevent accidental shock.
5) Exxpose battery tubes – The positive terminals on the battery tubes are square and the negative are hexagonal. Make a note on how they are arranged.
Testing The Nimh Battery Tubes
Before you test the cells let the battery stand for 2 days after you remove it from the vehicle. This is to ensure that the voltages have settled. It is very important that this is done. Not to do so will render the readings useless.
1) Test tube voltage – Using a volt meter measure and record the voltage of each tube. Start from the row with six tubes as row 1 (1 to 6) to row 3 (1 to 7). Depending on what voltage you started with you will be able to see the weakest cells as dropped voltages. These have to be changed.
You will not have the equipment to test the capacity of these tubes so this step have to be left out.
You will not have the proper chargers to recondition existing tubes either so thiat will have to be skipped as well
Remove faulty tubes and replace with good tubes.
2) Removing Tubes – Unscrew the opposite end before and remove the tube. If you strike a temperature cell make sure you carefully remove the temperature sensor as shown in the video before you pull out the cell. Check that the small screw is remove on the opposite side. It is easy to damage the connector when pulling out the tube.
Fault In Battery Computer
We repaired and reconditioned a battery for an Auto Electrician in Palmerston North. This unit had a faulty battery computer. We explained that we cannot offer our 1 year warranty if the battery computer was used in the battery as it will damage the repaired battery.
They managed to repair the computer and told us that “triangle of death” error was eliminated as well. This was good news and we now send all our faulty computers to them for repair. The cost to get this computer fixed is $350.
If the “triangle of death” appears, the battery computer is faulty. The battery low voltage condition triggers this fault. This error cannot be cleared with the S2000 scanner.
Final Steps
Congratulations you have just repaired your battery and you will know how to service them in future. Still a few things to note.
a) If you have the “triangle of death” error get your battery computer fixed. It will damage your battery if used with the repaired battery.
b) When putting back the battery pack double check that you have all sensor screws in place and all nuts have sufficient tension not too much as this can break the nut.
c) If you miss a sensor screw the battery fan will keep running after you start the engine.
d) If you forget to plug in the computer power supply the engine will cut out after a minute or 2
e) If you forget to connect the cables or connect them wrongly the car will not start.
f) when starting the car after you replace the battery turn the key to start then remove. Do it twice or more until you see the gear engage on the dash. The car will now start.
