Shut the A/C off?

Well, it doesn't seem to me that it could drain either battery, but it certainly can't affect the hybrid battery. There's a relay that disconnects the hybrid battery when you shut down the car; there's no path for the current to flow, so you can't drain the battery.

 

um, when you shut off the car the AC shuts off too.

not to mention even if it did stay on the HV battery is disconnected from the car upon shutdown. that's why you hear the relays clicking on startup.

i'd ask your friend where he got to be such an "expert"

 

I have noticed no problems with any of my batteries discharging after leaving the AC/ other stuff on when I turn off the car.

 

I leave my AC on also (Florida, of course) and haven't had any problems.

 

Maybe he's confusing it with leaving the car in neutral? That can run the battery down, but shutting the car off shuts the fans and A/C off too.

 

Also, if you have the AC on when you just hit the Power button (no foot on brake for ACC position), only the fans run, not the entire AC system.

 

Keydiver:
You can not leave the Prius in neutral and shut it down. It goes into park automatically on shut down. No need to ever put it into park first. Of course you can leave it in neutral and walk away, with it yelling (long beeeeeeep) and of course it will run the 12volt battery down only; no HV battery involved.

 

Start shopping for a new friend!

 

I leave the HVAC system in Auto, but as it is winter time, I keep the AC on off. I've noticed about 2 mpg difference.

 

Lemme guess, your friend doesn't own a Prius - Right?

 

That sounds old school. I remember when people used to shut off the a/c, radio and everthing else before shutting down a car. Rediculous if you ask me.

 

Could you ask her what page it is in the manual? That way we could look at it and see why she interpreted it that way.

 

"I was told by a friend..." **SIGH**
... and a Prius owner to boot.

The upside: Most Prius pilots are well-versed in the features, capabilities and caveats regarding their Prii, however, we still have some who still just "don't get it."

Technically, she's right... Without a doubt, use of the cooling capability of the "Air Conditioner" will consume energy which does have to be replaced, ultimately from gasolene (the ONLY source of energy in the Prius). Use for heating would also have a marginal effect since in cold weather the ICE would run enough to keep the cooling fluid warm. In any case, the overall effect would be so small as to be unimportant.

 

I basically think that Ron Popiel is a brilliant salesman and entrepreneur, so I'll quote him, "set it and forget it." In READY with the mode selector in P, R, D and B the vehicle is always able to maintain both 12v and HV battery levels inside the given computer parameters. No possibility of draining the HV or 12v system in a normal operating mode. If the vehicle is in N the vehicle cannot use the ICE to charge the HV battery. It is in this mode that it is remotely possible for an operator to drain down the HV battery, but not to a damaging level, but to the bottom threshold of the vehicle’s SOC tolerance and then the vehicle will just shut itself off to protect the HV battery.

Now if you leave a dome lamp on, a door ajar, the hatch open and loose you expose the 12v battery to drainage because lights are on which consume battery power. Those of us who have had the car long enough and have done enough “experimentation†have learned that the vehicle will only run in ACC mode for 1 hour and then the vehicle will turn off (learned this at a drive in theatre where stereo movie sound is piped in through car radios, really cool).

The car has many protections on the HV battery system that prevent any damaging drain on the HV battery. The 12v aux battery has nearly no protection against stupid operator syndrome. That is why we should all strive to be smart operators.

Since the A/C system is electric, the compressor is not connected to the belt drive system on the ICE. This means that the A/C system is not robbing power from the ICE, but is rather taking its energy from the HV electrical system. The compressor is also variable speed, so it only uses the electrical power necessary to maintain cabin temp at your setpoint. The closer the A/C system gets to your setpoint, the slower the compressor runs. This reduces the amount of power necessary to attain and maintain cabin temperature. The A/C compressor does use energy which has to come from someplace. That is going to be gas power that is then turned into electrical power while driving, or it could also be power gained from regenerative braking. However, vehicle driving performance is not reduced by having the A/C compressor running, unlike nearly all other vehicles with belt driven A/C.

Using your A/C system is essential. A long time I learned ago from a soft-spoken service department manager that A/C systems were, “use it or loose it.†It is essential that the compressor is run throughout the year to circulate refrigeration system lubricant which keeps seals, hoses and compressors lubricated and fresh. This prevents unnecessary wear on the system and prevents seals and hoses from becoming brittle which then allows them to allow refrigerant to escape.

So, use your A/C without fear, as you are doing both it and yourself a favor by utilizing it.

 

True enough. As Jeff Foxworthy said, "The first rule of marrige is that if she's not happy, you're not happy." No reason to cause any problems over something like this. Yet the more you know about the Prius the better you are. I did things based on cars I've owned before and found out I was in error.

 

But if it is cool out, the A/C won't actually come on, so how does that save gas?
I thought the A/C light was on to tell you that the system will be activated if necessary, but otherwise is "just as off" as if you turned it off manually, yes?