Last year I bought a 2007, 50th anniversary TCH, with nearly 100,000 miles already.

I notice the 12v battery looks remarkably clean and nice. On the top there is imprinted "04 09 09." COuld that be a date when this batter was manufactured or placed in service? The car's mfg date was April 2007.

 

It could be a replacement but more than likely, it is the original battery. Mine has over 100,000 on the factory battery and it is still going strong. With no starter load on them, the 12 volt is there to boot the computers and other normal system circuits without the huge load imposed by a starting circuit.

With the battery being behind the cover in the trunk, they stay pretty clean without any effort.

 

TNX, Georgia!

I just replaced the 12v in our Prius, several months older than the TCH but 35,000 miles less travels. I had had several clews that the battery was not up to par, so I bought the new Yellow-Top and replaced the OE batt after 5.5 years, 65,000 miles.

One way to reduce the steady drain on the 12v, I understand, is to switch off the Smartkey, which is easy to do in the Prius and I did so while the car was parked while we cruised for a week. In the TCH, turning the smartkey on and off is a pretty good ordeal!

Anyhow, that 04 09 09 looked so much like a date.... But it's hard to believe a 12v battery with no engine to start could fail in 2 years....

 

If it's Panasonic battery, it's prolly original one. Mine is still from the date car was made, in early 2007, and still works fine.

 

Does your panasonic battry have a date on its label?

As I mentioned, I was just anxioius about the unreliaability of the 12v in our 2007 Prius.... I've had no suspicious behavior from this one, and often the car sits for days at a time unused; for weeks at a time she may make 2 7-mile roundtrips to work per week and no other driving....

I understand the 12v is being charged whenever the hybrid system is in operation, regardless of the rpm of the ICE....

 

True. It charges from the 245 Volt traction motor battery. Does not need ICE running.

The main draw on the 12 Volt is when you are stopped. The smart key system is a constant drain, but you can apparantly turn it off, if you are not going to use the car for a while.

 

I actually did turn it off once! BOY! It's a long and tedious process, with much likelihood of making a mistake and having to start over.

I was pleased to find it was still pretty easy to use the system. Use the 'unlock' button on the key, for example, to unlock doors. Hold the key up in the general direxion of the ignition switch and touch the 'start' button when it lights up.... Remote control boot opener, etc....

I switched it back on (another long complex process) because it seems good to have both cars work the same way.

Don't remember right off where I found the Smwartkey off procedure, but I saved a copy in the owner's manual.... When we left the Prius parked at a seaport while we cruised the Caribbean, I mashed the handy button under the steering column to switch off the system, because I was getting worried about the 12v batt condition....

 

Still seems to me the voltage reading on the 12v is alarmingly low, although I see no other misbehavior. yesterday I put it on my 6A trickle charger and right away the charger guage showed a rather high reading, but within 10 minutes' time it settled down to the bottom....

 

you do not charge deep cycle battery with trickle charger. you charge them with deep cycle battery charger.

090806 is serial number, not date. so is yours. 04 09 09

 

oh, and battery should read at least well over 12V.