Battery level and discharge

I was out of town for two weeks in April and it didn't bother my 2010 battery.

 

Depends on the age/condition, assume we're talking about a regular 12 volt battery btw, not a hybrid battery.

If the car is sitting at an airport, it'd be a good idea to bring along a fully charged jumpstart pack, just in case. A week is about the limit I'd risk, but then, I'm a bit obsessive.

 

Visin the Hybrid battery is fine for months, it is the 12 volt battery that drains in weeks. There is a jump point under the hood to jump the 12 volt battery
http://www.toyota.com/t3Portal/document/om/OM47685U/pdf/sec_05_02.pdf
page 46 of this PDF, page 551 of the manual

 

Yeah, our car was manufactured in Aug '09, and SAT 'till Nov '10: accumulating dust in covered storage, there was a dead bird lying beside it, couldn't find a way out. The hybrid battery was fine, the 12 volt not so much.

 

One could disconnect 12 battery at the fuse/relay/pannel under the hood on driverside.(gen III only). Its the large white wire has quick disconnect plug..
I had wifes disconnected to charge dead battery for more than 12 hours. Without any problems.

The white wire under the hood that goes directly back to 12 volt battery is about the diameter of a pencil..I used that wire to charge the 12 volt battery... I don't remember if I lost radio presets like on a gen II (when disconnected) . The dealer programming was still good .The dealer had disabled reverse beep for us and It is still disabled...

Has anyone used this technique regularly (on gen III) that can report to us.??

With battery disconnected keyless entry doesn't work . If parked at airport you will have to use old fasion key to open door then hood and reconnect battery to open back hatch...

Some people report having to hit start button twice to ready car after 12 volt disconnect. First time doesn't work (i've never seen this).

The genII prius service manual says to reinitalize car after 12 volt battery disconnect by putting keyless key into ignition slot at the time of reconnect.. I also have never done this . Manual say you may generate some error code not doing this...I used scan guage for the first three years and now use torque app on android to monitor all prius parameters.(never had any error code yet).. And I disconnect battery at least once yearly to reset/.reboot all ecu's / computers..and get better gas milage doing after so. while car relearns fuel trims...

Gen II looses fuel trim memory , driverside auto up window function, a & b trip milage counts,and radio presets, when battery is disconnected.
The window auto up function is reprogrammed by holding the window up button 1 second longer after window fully closes...

All I remember when I disconnected gen III 12 volt battery. was that didn't loose reverse beep disable... I dont remember windows needing reinitalize, or fuel trim memory loss It drove exactly the same..

When gen II fuel trim is lost my prius runs like bran new others report loosing 5mpg.. My fuel trims seem to relearn at the 200 mile mark whereby my short term fuel trims are adding excess gasoline to air fuell ratio..giving me only 53 mpg... Right after fuel trim reset I get around 60 mpg (fuel trims running lean) for the next 200 miles then back to 53 or so mpg (rich fuel trims). My mpg quotes here are city stop and go driving...My gen II is 2009 has 76000 miles now (orignal tires only half worn) and has always run excellant always 50 + mpg... BUT after battery disconnect. reseting all ecu's / computers it runs better than excellant... Go figure...

Insidently gen III short term fuel trims are middle of the road compared to my gen II but I get the best milage ave. when I drive the gen III.
Wife gets about 5mpg less when she drives gen III . I get about 60mpg in gen III city driving..

I've only had gen III disconnected once when wife left door ajar at 3rd month of ownership ...our genIII is 2010 (35000 miles) battery doing fine ..nock on wood..