I have a 2005 Gen 2 Prius with 335K Miles on it. It has been a pleasure owning this though now the traction battery is on way out. I am still getting 48-50 MPG in summer instead of around 50 before. The battery now charges and discharges lot sooner that what it used to and I see 2 purple bars lot more often that before. I need to park the car for 15 days. I have parked it for 4-5 days in recent past after force charging it. I noticed after return although the battery initially showed charge level as what was before, it very rapidly went down. This time though I need to park it for 15 days or so. Would it be better to disconnect the battery completely by taking out orange plug in the trunk? If so what do I need to do after reconnecting? One of my friends had a battery die after a similar trip though his car had just 150K Miles on it. Thanks for your help.
the hybrid battery is already disconnected when you shut it down. there's no predicting when it will die, or how many days of non use might kill it. the shorter the better, obviously. you might want to consider a grid charger at this point, but idk how well it will work at your mileage. disconnect the 12v if it is old, or put a maintainer on it.
I do not think if traction battery is completely disconnected. Some functions such as boosting of Brake pressure keep happening during the storage. I believe removing the orange link should disconnect the battery completely and that should save the charge apart from internal discharge.
There's a relay controlled by an ECU that connects the hybrid battery when in Ready, but otherwise it is disconnected. Definitely no need to open up the hybrid battery compartment. The charge of the brake booster is a 12V system. The loss of charge over time of the hybrid battery is more a result of the battery technology, which will loose several percent a day for the first two days, then less and less over time. For two weeks of storage, if you want, do nothing. A good 12V battery should have enough charge to run the background electronics for at least a month, closer to two months if its new. However discharging lead acid batteries isn't good for them. If I were you, I'd force charge the hybrid battery to 6 or 7 bars and disconnect the 12V battery. Nothing additional required. If you have any upcoming fluid changes, its beneficial to do them before the storage period. I parked my Prius for 3 months with no apparent ill effects to the car.
I doubt force charging the battery would do any good if you're planning to leave it for 15 days. The cells will probably not even last 7 days, let alone 15. They start self discharging and the weaker ones discharge more, to the point it goes out of balance or a cell fails. You're probably going to need a new battery so why not just buy one when you return? Then you won't have to worry about the battery anymore, just drive your reliable Prius for another 100k miles.
As reliable as it has been so far, I am reluctant to spend $$ on a new battery. I can probably go with a reconditioned one. But not sure if there are any reliable sources around CT. It is best if I can avoid that in the first place. May be look for some one who can drive it around.
To recondition using a prolong charger, it'll cost you nearly $700, and you'll have to hope it doesn't fail. For around $1600, you can buy new modules and install them. A couple years of driving would get that back. And it'll be reliable and trouble free, unlike the remanufactured or reconditioned batteries
On a Gen2 you want to turn off the SKS (KEY) smart key system under the steering wheel, which drains the 12v. Then I just try to make sure the HV battery has a good level of charge. Upon return home, start car and let warm up for a few minutes preferably without A/C before pulling out.
You can always replace the bad module and since you have the prolong equipment already, rebuild the pack yourself . That would be a decent option.
