Hello,

I got in my Prius this morning to go to work - put the key in, pushed the power button, and nothing - no sounds, no warning lights, nothing; it was completely dead.

I drove it on Saturday, but not Sunday. It ran just fine, and no indications of any problems.


Any clues?

Thanks,

 

Most likely a light was left on and drained the 12V battery. Check for any doors not shut tight, map lights left on, etc. If you had remote start added to your Prius, that could be a problem as well - serveral TCH owners had dead battery problems due to remote starter installations.

Charge it for an hour or jump it (be very careful about + and - connections!!!) and it should start fine. Use a 6amp or smaller battery charger, and charge for 4 or 5 hours if you are not going to be driving the car.

 

You can charge the battery from under the hood. On the right as you face the car, is the fuse box. Remove the lid, and locate the red swing-away plastic cover for the boost point. The +ve goes there. The -ve goes to the bolt on the firewall just above it. You can also boost from these points. The car with a dead battery will draw about a 35 A pulse of 1/2-1 sec duration when you press the brake pedal, then another approx. 35 A pulse of the same short duration when you press "On". It will then start charging the 12 V battery from the traction battery, and will eventually start the engine from that as well.

I recommend the "doner car" engine not be running. No sense having the charging systems argue with each other.

When boosting, the sequence (from the owners manual as well as from best practices) is, connect +ve to Prius, connect +ve to doner car. Connect -ve to Prius, connect -ve to doner car - to a chassis point some distance from the battery. There will be a spark when you connect the last clip - which is why you don't connect to the battery. It can ignite the gas' in the battery and cause an explosion.

Do try to figure out why you killed the battery. Do you leave the head light switch in the on position and rely on the drivers door opening to turn them off? Did you "slam" the rear hatch closed? You don't want to fully discharge the battery too often. It looses capacity each time you do so (some damage always occurs). So finding out what happened and taking steps to ensure it doesn't happen again is a good idea.