Battery Died this am - do I need a new one?

Call around to the parts depts of your local Toyota dealers and find the best price for a replacement 12V battery. MSRP is $139.

Then ask your DH to install it (or if he can't / won't, plan to spend $100+ in additional labor charges at your Toyota dealer.)

Leaving the headlight switch on all the time may not be a good practice, if the headlights remained on after you left the car. The lights may remain on if you don't exit via the driver's door after making the car IG-OFF.

Is it possible that the jump instructions were referring to 2,000 RPM engine speed of the donor vehicle?

Good luck.

 

On any car, the 12 volt battery lasts about four years. you know they are near death when the starter sounds weak.

On the Prius, the 12 volt battery does not power the 'starter', the HV battery does. So Prius owners need other subtle clues. Low gas mileage, losing presets, slow power windows when not in READY, and suddenly having a dead battery one morning are these clues.

June 2007 to September 2010 seems a little short, but not by much.

You have two good choices:

You can buy another Toyota battery, they tend to be $140USD and $100 labor to install if you have your dealer do it.

For $165 you can get an Optima Yellow Top Kit from elearnaid.com and install it yourself. It is a more powerful, longer lasting battery, but will require modification to work.

12 Volt (12v) Toyota Prius Auxilary Battery for 2004, 2005, 2006, 2007, 2008, 2009 and 2010 with installation kit

 

The headlights turn themselves off only if you turn off the car and exit through the driver's door; if you leave through another door, or exit the car while it's on and reach in through a window to turn the car off, they stay on. Other common ways of draining the 12V battery include: not completely closing all doors and the rear hatch, leaving an interior light on, leaving the car in ACC mode instead of turning it OFF, etc. Locking the car with a button when you leave it will catch many of these because it will give a long beep and refuse to lock.

 

Our 2006 was dead this weekend as well.
Just drove 1 1/2 hours to the beach.
Main power and headlights were off but there must have been an interior light on.
Cooler may have kept hatch from closing completely.Hatch wasnt locking from button for the first few tries.
We were hiking 4-5 hours and when we came back it was dead.
This must be a rather tiny battery if it isnt needed to run an engine starter.
Could a healthy battery drain in 5 hours ?Could a new battery drain in the same amount of time?
A reliable shop says battery's fine ,but I have doubts.

 

If the hatch was open, then you may have had three lights on depending upon the light switch positions: the hatch light and two ceiling lights.

If three lights were on, this would have been a power load of ~30 watts or current flow of 2.5A. Over a five hour period, this would be a drain of ~13Ah.

A new, fully-charged 12V battery on a Smart-equipped Prius has a capacity of ~35Ah. Usually you can drain the battery to 50% capacity without harm.

In your case, with a battery four years old, it is likely that the capacity has degraded to half of the original value, or around 18Ah. Hence with a drain of 13Ah, not much would be left to start the car.

If I were you I would replace the 12V battery now, to minimize the likelihood of a future no-start event.

 

I don't remember any modification. It came with everything you need to install it, it fit the space fine, and the only problem was loosening the one bolt that holds the other "thingy" that sits above the battery. You better loosen that one first. Also, to remove the original battery and reinstall a new battery, remove the 10mm bolt that the negative cable attaches to the car at, not at the battery. Just make sure of course to attach the negative cable to the battery before you install it in the car.

 

The modifications include replacing the positive terminal connector which is bolted to the fuse block located above the battery, and replacing the negative terminal connector and cable with a new part. Both modifications are required because the Optima has standard-size battery terminals while the original equipment battery has smaller diameter terminals.

 

OK, I guess those do qualify as "modifications." And the difficulty I had was getting the bolt out of the positive terminal connector, so I suppose there was a bit more work, but nothing that was impossible. And I didn't have to actually modify anything, the eLearnAid kit had everything there, it didn't matter (at least to me) that the diameter of the terminals were different.

 

The OEM 12V is basically puny and you have to take precautions. I permanently disconnected the hatch and front door lights, I don't need them anyway. I only use the headlights when needed, not in the daytime. I lock the car, even in the garage as this assures me that there is nothing on, door, hatch left open, If the car will not lock, then it is time to investigate.