Unlike a conventional car, the NHW10 does not have a starter motor. The internal combustion engine (ICE) of the NHW10 starts only after the complementary, electic motor, is already running. So, if there is a problem with the motor or the high voltage (HV) battery that feeds it, the car will not start.

Problems with HV battery can occur if the car has been sitting unused for a few weeks or months. Much like typical recharable batteries, the car's high voltage NMIH battery cells become discharged even when they are not used. Old and worn out cells discharge even faster and can become flat in even a shorter period of time.

Foruntately, NHW10 comes with an onboard solution to this:

What to do it if doesn't start? Jump starting the Prius NHW10Edit

If, after a period of inactivity, the car does not start and/or displays a battery warning screen on the multi function display (MFD), try the following:

  1. Ensure that the 12V accessory battery is fully charged. Buy a smart Pb (Lead Acid) battery charger (eg Imax B6AC) or use a known-good battery from another vehicle. Alternatively, you can connect jumper cables to another vehicle that is running.
  2. Take the keys out of the ignition.
  3. Open the boot and find a single soft button of the emergency charger. This is located on the rear wall of the boot, near the top right hand corner.
  4. Press and hold the button for about 5 seconds until the green LED light next to the button turns on.
  5. Wait until the green LED light starts flashing and turns off.
  6. Put the keys in the ignition and try to start the car. 
  7. If the car does not start, first try to take the keys out and start it again a few times.
  8. If still unsuccessful, disconnect the 12V accessory battery and wait a for a few minutes. Then connect the battery and repeat the whole procedure. This might need to be done 3-4 times before the HV battery cells build up enough charge to start the motor.
  9. At times a red "Fault" LED will light up when starting a recharge. In such cases, let the vehicle sit for a few hours and try again.

Is leaving the car unused, bad for the battery?Edit

Does the battery get damaged by a long term period of non-use?

Opinions are divided on this, and it might depend on the quality and age of the cells as well as the conditions that the car experienced while disused. However, there have been cases of the car being left unused for up to 2 years and then being recharged successfully and running well.

On the other hand, in older packs, different cells tend to discharge at different rates. So leaving the car unused even for only a week can cause an imbalance in the state of charge of the cells in the battery pack. The car will then behave poorly and may require full re-equalisation of the battery pack. This is something that is definitely to be avoided. So if you are going on a holiday or simply not using the car anymore, it's a good idea to leave the car on a trickle charger or to lend it to a friend.