I am wondering is there a way to keep the 12 volt battery charged, especially during extended period of time the vehicle has to stand idle (with accessory on). I wanted to try firmly depressing the brake then press down the accelerator. This way the car won'y move but energy is being used from gas and traction battery to recharge the battery? Would like to know is this an okay method to maintain the 12 volt battery charged. Don't want to do anything stupid. Thanks,
It won't help. Having your Prius in Ready charges the battery as fast as the Prius can charge it, which isn't very fast. Driving, pressing the accelerator, or wearing a plaid suit won't make any difference. The Prius isn't like a normal car with an engine driven alternator. With the Prius, the 12V battery is charged by a DC to DC converter that generates full charging voltage anytime the car is Ready. Tom
As Tom implied, the way to keep the 12V battery charged when the car is standing idle is to keep it ON ("Ready"), in Park with the parking brake set. Then you can use the radio and whatnot as long as you want, until the car runs out of gas. Don't let that happen :_> Of course don't do this if the car is in a totally enclosed space with no ventilation. Any other method of using accessories risks draining the 12V battery (an annoyance) or the traction battery (an expensive annoyance).
The "forced charging" you are refering to is a way to raise the State of Charge (SOC) of the big (HV) traction battery, not the little 12v battery. If you want to maintain the charge on the 12v battery either take a long trip or use a "Battery Tender" while your Prius is parked. JeffD
With Pearl, I've found, at temperatures -below- freezing (sometimes -way below-) you have to have the car in "ready" for at least one hour per week to keep the 12V battery in a reasonable state of charge. The warnings above were implied. I will state them directly. DO NOT wait in "N". The traction battery will not maintain charge. ALWAYS after putting the car in "P" with the parking brake on, and shutting off the car, open and close the drivers door. Just to make certain the headlamps go off. This is mainly applicable when you plan to sit and wait in the car with it off. Other than these "gotcha's" it's pretty simple. Have the car in "ready" for at least one hour per week and you should be good. You can go several weeks without doing this, of course, such as when going on vacation with the car waiting patiently for you. Probably 4-8 weeks depending on the health of the battery.
Ah. I inferred the OP wanted to keep the 12V charged while using accessories. If one wants to re-charge a 12V battery that has been drained the best way is not to drain it in the first place :_> A Prius is not a fast charger and is an expensive battery maintainer.
