Leaving Prius 2007 idle for six months

Disconnect the 12V battery ground wire and you'll be OK. A solar, tickle charger would be a good idea too but it needs to be connected to the battery.

GOOD LUCK!
Bob Wilson

 

Hi Krisam. I strongly recommend you either have someone else drive it periodically or isolate the traction batt by pulling the service plug on the side of the batt and disconnecting the 12v batt also. This scenario has potential to cause you probs if not managed. They can be troublesomevif left as the battery packs can bleed off in that time causing big dramas later.

 

1. Change the engine oil and oil filter prior to storage.

2. Inflate the tires to 44 psi. Ideally, raise up the car on jackstands to avoid flat spotting on the tires.

3. Close all windows.

4. Look at the MFD state of charge gauge for the traction battery, and get it to 7 or 8 bars before you store the car. To achieve that, do a force-charge: make the Prius READY, shift to D, press hard on the brake pedal with your left foot to hold the car stationary, then floor the accelerator pedal with your right foot to force the engine to run. Since the car is not moving, MG2 is held stationary, MG1 will spin and its energy will be routed to the traction battery. (You are overheating the transaxle via this procedure so don't do this force-charge repeatedly.)

5. Fully charge the 12V battery, then disconnect it. The best place to disconnect the battery is at the main relay/fuse box next to the inverter.

Open the hood and remove the relay/fuse box top lid by pressing hard on the latch at the front of the lid, and pivoting the lid up. Open the hinged red cover over the dedicated jumpstart terminal, and note the nut there.

Use a 10 mm socket to remove the nut. Then use a pair of pliers to pull up the wire attached to the stud. Put the nut back on the stud, close the red cover, put the wire over the cover, and replace the lid on the relay/fuse box.

Close the hood, lock the doors, and you are good for storage.

When you return, use the mechanical key in the fob to open the driver's door, then you can open the hood and reconnect the 12V battery.

I suggest that you make sure the mechanical key works in the lock, prior to disconnecting the 12V battery and locking the car...

 

Please correct me if I am wrong but isn't the easiest way to disconnect the 12 battery for storage is just unplug the big cable off the positive post fuse assembly on top of the battery. I know your supposed to unbolt the neg first if changing it but the main and secondary from the positive post fuse assy on the 12 volt just unclicks. Compress the tab and pull comes right out. No unbolting required if just storing. Just unclick it and your done. No tools.

Before inserting mechanical key in door shoot some spray lube in the lock hole. Spray some on the key itself. That lock has never been used in 6 years so go easy. I try mine once a year. I use CSP spray from Home Depot. Then gently try the key. Spray a little more in the keyhole. Try again. Should lock pretty easy. Don't force it.

Not necessary to pull hard on fuse box cover. I go to the other end the backside of the box towards the driver and gently push in the bottom of the box where it meets the top cover. Cover comes right off really easy.

 

That might be the easiest way to disconnect it, but its much easier to pop the hood than the trunk without the battery hooked up to reconnect.

The 12v battery would be the least of my worries. Make sure the HV battery is fully charged. The best thing to do would be have someone drive it every couple weeks.

 

No just put the hatch down softly. Believe me there's no problem closing the trunk and not having it lock.
Hard enough to get the trunk to lock just closing it normally.

This way there's no tools and no rookie going at the battery connections with tools. That's not good. Avoid that.

Toyota made the 12 volt battery easily dis connectable for a reason.

 

Bruce the traction battery is completely isolated as soon as you turn the car off. There are two DC HV relays that disconnect both HV lines from the rest of the car. Disconnecting the 12 volt battery removes all possibility of them re connecting.
I have fitted a traction battery from a breakers yard into a Prius after standing over 12 months. It still showed 3 blue bars in the car it was fitted in to.

John (Britprius)

 

Yup...John's right. Don't remember anyone ever posting about dead Hybrid after long idle in 6 years here. Its a non issue. And pulling the Hybrid battery orange safety plug won't help do anything either.

The 12 volter is another deal. That can be disconnected in seconds using the tools Toyota gave you.

 

...for shorter holding periods, a simpler approach might be possible, believe the 12v battery drain can be minimized by turning off the smart key system with the buttons under the steering column. In the case of 6-months hold better to totally disconnect 12v.

 

I plug in a 2 amp smart charger for the 12v and force charge the Hybrid battery All is good when I get home. H

 

The Gen2 does not suffer from the buss bar corrosion issue the G1 had. Not alot of corroded bars and connectors on a Gen2 battery like they were seeing on G1's. Superior battery module I suspect. Less off gassing. Gen2 seems quite happy sitting idle for months.

As far as force charging the hybrid battery that's not necessary either. Put the car in Inspection mode. The engine will run until you shut it off.

Much better than powerbraking the trans. That's really hard on the trans and the mg and heat will build up fast. Go into Inspection mode...turn off all accessories...no lights..no ac..no radio. Let the engine run until there is no more arrow from MG to Hybrid battery. Done.

Do not drive the car in Inspection mode as traction control is disabled. Damage will result.

 

A Prius mechanic once showed me a burned-out MG2 from someone having done exactly this. Since the traction battery is completely disconnected when the car is off, I don't think this is necessary. In normal use, the traction battery generally tries to stay around 6 bars, and I think this is plenty. In fact, I believe this is healthier for the battery than storing it fully charged. My Tesla Roadster takes itself down to around 40% SoC in storage mode. (Plugged in, so it can maintain a healthy charge level.) Different kind of battery, but still, six bars should be fine.

I only drive my Prius once every few months, since the Tesla is now my daily driver. I keep the Prius 12-v plugged into a battery minder. My Toyota dealer installed a lead, so I can plug in and unplug easily without opening anything but the rear hatch. Since the car lives in the garage, I run the extension cable through the open window.

 

MG2 will not be over heated carrying out the procedure outlined since no power is applied to it with the brake pedal depressed.
This can clearly be seen on the MFD. In ready mode and D with no brake pedal current is drawn from the battery by MG2, as soon as the brake pedal is depressed the current flow is removed.
Only MG1 is rotating producing current to charge the battery, and in this mode the transmission oil pump is active helping keep things cool and lubed.
This is exactly the way the car looks after the state of charge of the HV battery when you sit in traffic with the AC on.

John (Britprius)

 

The MFD does not show actual current. It's just a picture telling you whether you are charging or discharging the battery, and whether the battery, the ICE, or both are powering the wheels. Again, the mechanic showed me (and a few others) an MG2 that was destroyed by someone trying to charge the traction battery this way. Very sad, too, since the owner was apparently ingorant of the fact that the car maintains the charge on the battery and the driver does not have to worry about it.

The OP does not have to worry about it either. The 12-v battery, yes, and all the stuff about the oil and the tires and whatnot. But you don't need to "charge" the traction battery. Maybe if you're down to the last two bars when you're ready to put the car into storage you'd want to drive for ten minutes on level roads to get it to 5 or 6 bars.

 

Charging the battery in the way described cannot hurt MG2 . According to both Priidash and Techstream the current under these conditions is zero to MG2.
The Prius tech has no way of determining what burnt out MG2.
What you are saying is MG1 the smaller of the two motor generators "rated at about half MG2" can supply enough current to charge the HV battery and still have enough current to burn out MG2 without destroying itself.

John (Britprius)

 

^ Running current through a motor when the motor is prevented from turning is what's bad for it. In any case, it is unnecessary to charge the traction battery above what it normally keeps itself at (5 or 6 bars).

 

But I have already established there is no current. The bad thing for MG2 is to apply the parking brake without putting the car in park as this leaves current being supplied to it. It is only when you press the foot brake that the current goes to zero.

John (Britprius)

 

Om my car in this mode I see yellow errors from battery to the wheels with foot on brake and gas floored and the car is not moving which means there's power to mg2 but its stalled. Or it means the mfd is detecting you're in gear and pushing on the gas so it's showing the yellow lines but not actually sending power to the mg.

Still not a good way to force charge the battery. Car was not designed to do this. If your foot slips off the brake it slams pretty hard.
All you need to do is make the engine run. Toyota gave you that with their Inspection mode.