Leaving Prius For 5 Weeks

[barrycoll]

After the slew of posts describing dodgy 12 v batteries, I am wondering what advice folks might have for leaving 9 month old Prius in my drive for 5 weeks, unused, during Feb etc???

will it be dead after that???

should I plug in a Ctek charger before hand, although maybe the car will be un openable with a flat Battery, (but perhaps I should check out the manual opening before February!!!....)

the IQ manual opening doesn't work without the alarm going off, but that is something to do with double locking that I havn't figured out

[beachlife]

I left my Auris HSD for 3 months September to December connected to a Ctek and car started first time. So I don`t think you will have a problem. However my car was in a garage not sure I would want a cable running outside if your drive is too public, as the ctek would be a tempting piece of kit to get pinched. ( especially to other club members without a ctek)

[PeteB]

In the early days, when we only had the Classic (saloon) Prius, the advice was to disconnect the 12v Battery. Of course, it was possible to open the boot with the key, or a lever next to the driver's seat like the one for the fuel cap. In later models, with the electric boot release, it's more of a problem.

If you chance it and the Battery does go flat, the alarm will probably go off for a while when the voltage gets low. You could lock the car with the emergency key, which doesn't set the alarm thus reducing the load on the 12v Battery a little. However, you lose the deadlocking feature if you lock it this way which obviously makes the car less secure. If you return and the battery is flat, then using your (tested!) emergency key you can use the jump start terminals under the bonnet, but it may have damaged the 12v battery by then. In this case, the alarm will probably go off until you go to 'Ready' mode. You will probably have to reset the clock, radio presets and many other settings. That presupposes you have access to a jump starter or leads you can connect from your IQ.

The Gen 2 Prius had a higher rated 12v battery and slightly lighter drain when the car was locked than the Gen 1, and some people did find it could last 5 weeks in ideal conditions (no faults, nothing left on, battery good). Logically, I would have expected the Gen 3 to be better still, but given the various discussions here that doesn't seem to be a foregone conclusion.

Another option, if feasible, is to find a local trusted friend or relative to put the car into Ready mode for ½ hour or so a week which should be enough. If you knew/trusted someone well enough to let them drive it once a week even better. Shame you solar panels can't be routed to the 12v!

Regards, PeteB

[johalareewi]

I have left my gen3 T3 for 4 weeks and it was fine.

But as with all things YMMV.

[PeteB]

Presumably, T-Spirit will have slightly higher drain as it has full keyless entry as opposed to T3 which only has it on driver's door

[barrycoll]

thanks Pete, and Alan....looks like 5 weeks is unknown territory, and I feel like a bit of a pioneer

there is no neighbour that I could ask/trust to use Ready mode Pete, and (just maybe) I am being a bit over cautious here, and should just trust to Toyota R&D

my series of diesel Golfs never batted an eye over being left and then starting on the button, but that is the advantage of a big Battery

I don't have a Ctek charger as yet, but I have a Halfords Smart charger that sorted out the IQ before i bit the bullet with a new Battery...the Smart charger turns itself off when temps get it bit hot for comfort (hopefully) and when left on for long periods and goes into maintenance mode....

would it be reasonable to connect the Halfords charger to the 12v Battery terminals in the boot, and leave the mains plug emerging from the boot lid, but maybe taped up under neath the car....ready for action if needed??

any thoughts?

[steverally]

Would it not be possible to leave the charger connected to a seven day timer switch that would maybe gives it a charge for a period say once or twice a week?

[cviclark]

I have left cars connected to an Airflow Battery conditioner (similar to CTEK but much older) for months, when in the forces. My Prius and Auris had/has charge points under the bonnet and both can be left with the charger/conditioner in maintenance mode connected. The lead can be fed under the car so the bonnet can be shut and all the doors locked as usual. Any quality charger should have a maintenance mode nowadays but my Airflow was bought in the 70's on the advice of Honest John. In those days they were expensive and only used by classic car people. If you take the Battery out do not leave it on a solid concrete garage floor.

When you get back let us know if it survived, good trip.

[Sagitar]

I don't know the Halfords Smart charger. The specifications for the two versions in their catalogue appear to be appropriate, but I did read a few reviews. Based on those reviews I would not use it on the Prius with the Battery in place.

I have an Optimate 4 which I know works with the Prius and the Ctek looks good also (based on the comments above). I bought the Optimate 4 on the recommendation of the Toyota dealer who does all my servicing. Have you spoken to your dealer about the issue?

Before leaving the charger attached to the Battery for a long period, I would follow the normal charging instructions to the point where I was satisfied that the Battery is in good condition. If the battery is in good condition, the charger may be left connected for an extended period and will periodically offer a float charge within a safe 13.6 volt limit, allowing the battery to draw the small current needed to keep it close to full charge and compensating for any load imposed by vehicle accessories and the normal self-discharge of the battery.

(My comments are based on the Optimate 4. Perhaps someone else can confirm similar conditions for the Ctek).

The Optimate 4 operates at very low current levels - not more than 0.8 amps and as low as 0.2 amps when float charging. It will not therefore fast-charge and from everything that I have read, that is a good thing, especially when the battery is in circuit in the car.

I must emphasise that I am not an expert on battery chargers and my comments are based only upon my own experience of using a particular charger and following the instructions for that charger.

[wass]

If you intend yo leave the car outside and unattended for 5 weeks, why not just get used to the fact that the 12v Battery will go flat during that time and buy a booster Battery pack in order to reboot the cars computer on your return. I do this and it works extremely well. The booster Battery pack doesnt go flat because it is independent and has no power drain. The power required by the car to start up the systems is minimal and well within the capabilities of the booster battery. I have owned my battery for just over a year during which time i have needed to use it 3 times and I recharged it more out of guilt than necessity last week. I keep it in the boot because the booster pack also contains a handy high powered lamp and an air compressor.Connecting the unit up to the under-bonnet jumper terminal is very simple and quick. A flat battery event takes just 5 minutes to solve since once the drivers door has been opened , the prius boot may be easily accessed from the cabin to retrieve the booster and then you pop the bonnet and connect up using the inbuilt booster lamp in order to see what you're doing.

[barrycoll]

thanks for all the help on offer here folks, and it does show quite a level of creativity.....

basically, more than one way to skin a cat, as it were........however, my original thoughts were to leave the Halfords charger connected to the 12 v Battery terminals, drape the lead out the boot, and then tape the power plug up under the boot somewhere, ready to be plugged into the mains on my return...

basically, not even trying to see if the car will start or the doors will open, before giving it a few hours boost...

1...but.....will the Halfords connected up (but unpowered up) charger, cause any additional problems?

2...which is the power booster pack you use Geoff???

3...should I junk my Halfords number and just get an Optimate 4 or a Ctek????

[PeteB]

I'm not sure, but I wonder if leaving a charger connected but unpowered might actually increase the drain very slightly on the 12v Battery?

[timberwolf]

thanks for all the help on offer here folks, and it does show quite a level of creativity.....

basically, more than one way to skin a cat, as it were........however, my original thoughts were to leave the Halfords charger connected to the 12 v battery terminals, drape the lead out the boot, and then tape the power plug up under the boot somewhere, ready to be plugged into the mains on my return...

basically, not even trying to see if the car will start or the doors will open, before giving it a few hours boost...

The maximum recommended charging rate for my 12V Battery is 4 Amp. If the Battery has been left powering the car for 5 weeks, it will need a minimum of 10-12 hours to recharge and realistically to fully charge up you would be looking at 24 hours. Charging a lead-acid Battery from a mains charger is a slow business. The Dealers have faster and definitely more expensive chargers, but that may not necessarily be good for restoring/reconditioning the 12V battery.

1...but.....will the Halfords connected up (but unpowered up) charger, cause any additional problems?

Additional current drain.

2...which is the power booster pack you use Geoff???

You'll still have to charge up the battery after 5 weeks.

3...should I junk my Halfords number and just get an Optimate 4 or a Ctek????

You have to ask about junking an unknown design of charger with a Halfords label!?

As I understand it, an Optimate 4 can not charge a flat or nearly flat battery (which it is very likely to be the case after 5 weeks of standby drain).

As you car is parked on the drive I wouldn't want to leave a charger attached to my car.

Your 12V battery has an unknown state of charge at the moment? I'd use a Ctek charger (or equivalent) to fully charge the battery for 24 hours (it is fairly safe (98.9999%, nothings ever certain!) to charge the battery in situ), a week or two before your trip. On your return, I'd do another 24 hour charge - if I needed to use the car right away I'd probably charge for as long as I could say 8 hours, drive the car and because I do limited mileage, I'd then reconnect the charger for another 12-14 hours.

I've noted with my Ctek that it will indicate that it is charged in less than 12 hours (green LED) but it really is not fully charged at that point.

[Grumpy Cabbie]

Why not just disconnect the 12v? That way it'll be ready to go when you get back and reconnect it.

If you allow the 12v to run totally flat when attached to the car, it 'may' do permanent damage. Refer to the many posts about weak 12v's after a few years. You don't want to help it to an earlier demise.

[barrycoll]

well that is a left field approach dear Grumpy....if I disconnect one of the terminals, can I lock the car (??)....and then re -open it later??

in the meantime, I have ordered a Ctek 5.0 from my mate Mr Amazon, as per Timberwolfs advice.....seemingly I can give the car a 24 hit before leaving, then leave the charger connected but unplugged fro the mains, and then another 24 hours later on...

[timberwolf]

Leaving the charger connected is not a good idea as there would be an additional current drain from the Battery. By charging in situ, I meant you do not have to remove the 12V Battery from the car.

I think it is possible but you are on the edge and there is no guarantee that the Battery will not be flat on your return. You will shorten the life of the battery.

Mmmm, disconnecting the battery, there would be no alarm, various settings such as the window, radio, possibly MPG? values may reset and I don't know about the lock on the boot.

You could also ask your dealer if there are any fuses that can be removed to reduce power consumption? I think on the Prius Gen 2 there was a fuse removed to reduce power consumption whilst being shipped from Japan to England.

[Sagitar]

"As I understand it, an Optimate 4 can not charge a flat or nearly flat Battery (which it is very likely to be the case after 5 weeks of standby drain)".

No, that is a misunderstanding. When a 12v Battery goes from fully charged to discharged, the voltage across the terminals changes by only about 10%. i.e. a discharged but otherwise healthy Battery will still show more than 11 volts.

The Optimate 4 will not switch on if the voltage across the battery is less than 2 volts, but it will not have any problems with a healthy but discharged battery. Not switching on when there is less than 2 volts is a safety measure. A voltage as low as 2 is an indication of a damaged battery and the application of current to it is likely to cause over-heating and possibly a fire/explosion.

The Optimate 4 (and I believe the Ctek) is designed to deliver a float charge over an extended period without disconnecting the battery from the car. This will maintain the float voltage and the battery will remain fully charged. It is important, to check that the battery is healthy before doing this. If the battery is deeply discharged and possibly sulphated, it is essential to disconnect the battery from the car before connecting the charger for a recovery attempt. The charger's recovery mode cannot engage if it senses that the battery is connected to a vehicle wiring circuit, since this circuit will offer a lower resistance than the battery alone.

[wass]

"You'll still have to charge up the Battery after 5 weeks." ....experience indicates that this is not the case Timberwolf. Driving the car is sufficient to return sufficient power to the Battery to boot up the computer on subsequent start attempts.

Barry...The unit I use is a cheap one from Amazon at £30.99 although there are some considerably more expensive units on the market which are capable of starting up diesels and the like. It is listed on Amazon as a "portable power station"

[valmiki]

I am currently overseas on a 4 week holiday to visit family, I've left my T-Spirit Prius on the drive with the Battery hooked up to a LIDL smart Battery charger (under £15 but pretty decent build quality), with the wire coming out of the boot and into the garage.

The charger is visible through the rear hatch window and an LED shows what state the charger is in. The night before I left I wired it all up, and through the window could see the Battery was charging. In the morning, the LED had switched to Fully Charged, and was trickle-charging. That was 3 weeks ago! If the car had melted down or whatever I'm sure my neighbours would have contacted me before now, but I've done this before and never had a problem.

[edit] I've read to death all the problems of Toyota batteries in hybrids, whether Prius or Auris. The minute mine shows signs of waning I'm going to drop in the biggest/baddest one I can find! (Most probably a Bosch S3/S4 depending on which one fits)

[beachlife]

If you do fit a larger Battery like the Bosch S3/S4 can you leave the car for a long period without any problems?

If so whats the longest any one with such a Battery has left their car without it letting them down? Or do they still have to use a maintenance charger connected?

[valmiki]

Dunno! But I'd feel safer just driving around (esp. during winter) with a Bosch than Toyota's measly one. I'm thinking I still wouldn't leave it for extra-long periods without it being trickle-charged now that I know how easy it is for me to do.

Sorry, probably not the answer to your problem :-|

[cviclark]

If you use a Battery conditioner like the Airflow or CTEK do not disconnect the Battery. Do not leave anything connected and not plugged in. They are not designed (and will not ) to charge a flat Battery. They are designed to maintain a float charge, continually monitoring the condition of the battery and adding a little if needed. I have left a battery on the Airflow for 9 months with no ill effects, this is why it cost such a lot. Mine has a series of lights that tells you its connected the correct way, max volts 12.4 min Volts 11.4 ( i think) and lights to show when its working. The idea is to stop the plates from sulphering up while not boiling off liquid.

Forget connecting in the boot, the charge points are under the bonnet (RTFM), I have had a flat battery in a Gen3 Prius and after 15 mins from a normal charger connected to the charge points all was fine.

Dont worry about it, even if its flat an nice RAC or AA will give it a boost and it will be fine.

[timberwolf]

I required a Battery charger that was flexible enough to also revive/recover unhealthy batteries, I thought it was more likely that I would need that, shrugs. My CTEK wins on ease of use, as all the charging modes (bulk, trickle, etc) appear to work with the Battery still connected to the car.

From my own experience, my car usage, just at the weekends, is insufficient to keep my 12V Battery fully charged.

[cviclark]

I agree with Valmiki. First sign of a problem fit the Battery with the biggest ampere hour rating you can find from a reputable make.

Look up OHMS law. V= I x R. Watts= Volts x Amps. Think of Watts as being Ampere hours ie the number of amps depleted in an hour and you wont go far wrong. Google will tell you the exact formula to work it out, or any kid doing O level science,

Why the heck Toyota fit such a weedy Battery is beyond logic. The US Priuschat brought up this subject years ago.

[valmiki]

I would try and avoid a flat Battery in the first place, it will reduce it's overall capacity which will only ensure it gets flattened even quicker in future. Probably not a good idea to have even infrequent flat batteries!