Yaris Cross 12v Battery

[R-J]

I am soon to go away for some weeks and will leave my Yaris Cross on the driveway.  I expect that, on return, the 12v Battery will be flat.  Rather than get the AA out to jump start the car I have tried to explore ways of keeping the Battery charged.  Putting the car into ready mode for 60 mins a week (https://mag.toyota.co.uk/coronavirus-toyota-hybrid-car-maintenance/)  is not a practical option for me)
I can think of two other options:
1. Plug a solar charger into the OBD port.  As the panel should be kept inside the car connecting the panel to the Battery charge points under the bonnet does not seem feasible.  If my idea is practical could I use a panel I bought from the AA a few years ago or would you suggest something different?
2.  Connect the battery to a trickle charger such as the AA 1.5 Amp 6 V/12 V Car Battery Charger Maintainer AA4956, a CTEK MXS 5.0 Battery Charger or a different device you might suggest?  I am cautious about this option as the car would be connected to the mains for a significant period of time.

Any advice would be appreciated.

[IT Troll]

I would say solar for the drive and maintenance charger for the garage. A mini jump starter Battery is useful for emergencies. Have a read of the big 12V Maintenance thread for some recommended products.

[Roy124]

IT Troll has covered succinctly all the bases. 

[Jimota]

I’m due to visit Australia for 5 weeks in March 2023.  Even after all the viewpoints about the best way to preserve Battery life, I still don’t know what is the most effective system  to prevent Battery drainage.

[Cyker]

A decent smart trickle charger is probably the most effective; Solar charger a bit hit and miss, esp. this time of year. If you have a trusted neighbour that might work too.

Could go old-school and disconnect the Battery but it's a bit of a faff getting back in to hook it back up with no power, and always that slight risk of shorting something accidentally!!

If you turn off the smart entry system it might drop the standby draw low enough to survive, but the longest I've left mine was only 2 weeks - not sure about 5!!

 

[dave hendy]

The better option is a smart charger, but if the car is outside a solar charger helps but isn’t as effective during the winter.

[RobertR]

I will be also off during the holydays, about the 2 weeks, this should be fine, right? Nut maybe for piece of mind a put a triccle charger on the Battery.

About the solar panel chargers with regulated 12V output, they are some solid to be bought and I'm sure you can buy some extension 2wire cable(or you have some in home) and run the cable from under the hood, thrue the outside panel gap cavities into the cabin(small dialemeter cable will fit into the panel gaps to be covered from the "corious" people) where you placed safely small solar panel (5-10W), no need to hassle with OBD socket. (OBD socket is communitation port with car cpu, I will be carefull do do that, you mate create some ground loop or some voltage divider and do some damaged)

[Mojo1010]

Has anyone manage to start the car after being away for 7-9 days in the winter? Car not garaged. Not gone more than 4 days in the winter without driving the car, so quite anxious as whether it will start. Going away some time in Jan/Feb. Have been considering a smart charger, though if it can get away without buying one. 

[TonyHSD]

27 minutes ago, Mojo1010 said:

Has anyone manage to start the car after being away for 7-9 days in the winter? Car not garaged. Not gone more than 4 days in the winter without driving the car, so quite anxious as whether it will start. Going away some time in Jan/Feb. Have been considering a smart charger, though if it can get away without buying one. 

Me, but an older car - Auris Hybrid 2010 without any connected services. Car been left up to 4 weeks during summer and up to two weeks during winter without any use. Prior to that the car was a low mileage second car in the family and only was used for short daily school runs of 3 miles (30 min or less drive). Still on the original batteries. 

[Roy124]

The answers are all here but the best is 'it all depends'. 

Garage with power, protected, secure, and get a charger. 

Garage without power, protected, secure, get a jumper Battery. 

Ditto, disconnect Battery. 

Open parking under cover, power available, get a charger. 

Open parking, no power, shade, get a jumper Battery. 

Open parking, no power, no shade, get a solar panel. 

Airport parking, no power, unknown shade, get a jumper battery or hope the car park has a jumper. 

There will be other permutations. I have a charger and jumper. I used my jumper as a test and it worked a treat. After jumping I recharged it in April.  I checked it yesterday and it still shows 76-99% charge. 

 

 

[Roy124]

A note on jumper batteries, they are available at under £40.  They are pocketable and usually have an LED lamp.  They can be used to power your mobile. 

They might save your life. 

[RobertR]

Unfortunately, that's how it is and it's not a Toyota's specific, all hybrid vehicles must be driven several times per month to maintain a charge.

It's hard to understand why they don't put some cut-off voltage limit for 12V Battery, where almost all electronics will be disconnected, like keyless, MyT connectivity, etc, The car will be dead anyway after a while, so why then ensure at least your will be able to start the engine. I'm sure Toyota's engineers aren't that stupid to don't know this issue, so they must have a good reason to do it this stupid way.

[Gerg]

3 hours ago, Mojo1010 said:

Has anyone manage to start the car after being away for 7-9 days in the winter?

I did some simple measurements of the parasitic load on the 12v Battery of an Auris hybrid a while back on another thread.  I was using a UNI-T 210e clamp on current meter.  The currents we're talking about are very small, so the meter readings are not to be taken as especially accurate for that device, but they were very repeatable, and do give a guide!

My maths isn't that great, but anyway...

Car locked, Keyless locking enabled - 0.050A

Car locked, Keyless locking disabled via dash - 0.028A

But, the Keyless locking is supposed to go to 'sleep' after 7 days of being unused, so the parasitic load will likely become 0.028A after 7 days.  But let's assume this doesn't happen, for the moment - err on the side of caution.

Assume the 12v Battery was fully charged up, and it is a 35A/hr Battery (I don't know the Yaris's size, so this is a guess).

0.050A x 24(hrs) = 1.2 A/hr of battery capacity per day to power the car when parked. 

So assuming 100% battery efficiency and an as-new battery (a bit of a tall order, but still), 35A/hr divided by 0.050A = 700 hours of 'parked-up' before your battery is completely flat.  Just over 29 days.

A good idea would be that you only want to discharge your battery to 50% capacity (as a very intermittant happening), so you have just over 14 days of parking to reach that 12v battery charge of 50%.

If you turn off the Keyless locking before you park then this becomes greatly extended.

Knowing that you are leaving the car with a fully charged 12v battery is a big variable in this, and something you can help with!

To start the car's systems (computer, contactor, pumps etc.) takes a short burst at 20 A from the battery.

I'm not sure all that helps you though!

Or am I missing something in the maths above?

[Mojo1010]

That's very useful to know. 

Don't have keyless entry on my car so according to your measurement for 10  days the car would drained approx 6.72A. How cold it is would also be a factor. So my car should start fine. 

[Roy124]

Missing from the consumption are things like the alarm which will be active.  There will be a small drain keeping the computer and radio connected.  If there was no drain there would be no issue disconnecting the Battery. 

The car may also do regular hand shakes with mother.  It certainly sends its location and fuel state to mother but does this happen instantaneously on shut down or periodically? 

Regarding the hand shake, in the Yaris Cross it sends the door lock status home and listens out for the owner to command door locking.  It is also listening out for command to switch on the heating and flash the lights in its here I am mode. 

[Cyker]

I left mine for pretty much all of the Xmas holiday last year and it fired up just fine so 2 weeks should be okay. I didn't even disable the keyless entry (I don't think I even knew you could back then  )

I do drive it a lot tho' so the Battery would have been as charged as it was ever going to be; For people that only drive occasionally, results may not be as favourable!

It would be worth investing in a cheap power bank just in case, maybe hint at loved ones for xmas  

If nothing else it can charge your phone and tablets on the go!  

(Just don't do what my colleague did and waste all the charge on his phone and kid's tablet, then didn't have any charge when he actually needed to jump start the car  )

 

[Jimota]

This will be my first venture into the hybrid word but some modern ICE vehicles are also susceptible to Battery drainage if left unattended for weeks on end.  As I’ve said elsewhere on the forum I visit Australia every year for periods between 4 - 6 weeks but I’ve never encountered a problem starting the car on my return.  My car is usually parked outside during the late winter and early spring months.

[PJR77]

I parked my Yaris Cross for two weeks at Heathrow. On return it started immediately. I made sure to turn off the radio and internal light just in case. If a car cannot be left for 2 or 3 weeks then it is not fit for purpose.

[Roy124]

57 minutes ago, PJR77 said:

I parked my Yaris Cross for two weeks at Heathrow. On return it started immediately. I made sure to turn off the radio and internal light just in case. If a car cannot be left for 2 or 3 weeks then it is not fit for purpose.

By definition, your Cross Battery is still very new. Two weeks should certainly be doable.  IIRC my Corolla failed in its first year as it was out of use for much longer during lockdown. 

With a new Battery at the 12 month point, a warranty change rather than completely u/s.  At the next 12 month point the new Battery was fine after 16 days but then failed when laid up when I had covid after just 8 days. 

As I have said, and Cyker too, a less than £40 jumper pack is a worthwhile investment. 

[Gerg]

1 hour ago, PJR77 said:

On return it started immediately

As well as all that posted above, the characteristic of the Toyota hybrid system is that with regards the 12v Battery charge, it will start perfectly, right up to the occasion when it can't start at all.

The tell-tale laboured chugging that comes with a 'flattish' Battery on conventional cars isn't there on the hybrid, so you don't get given audible warning regarding the charge of the 12v Battery.  It is much more binary. All the hard work spinning the engine is being done by the 'traction' battery.

Having a multimeter or similar to check your 12v battery can pay dividends.

[Cowgirl]

I’ve just returned from 2 weeks away, Battery would have been fully charged on arrival at the airport but after hearing a few horror stories I use a solar charger just to keep it topped up. Started straight away.

[Roy124]

An answer the Greg's observation is a wired bluetooth Battery monitor. I haven't tried one so this is not a recommendation. 

They can be bought in the £20-£30 range and using an App you can monitor the Battery state and receive warning if the voltage drops. 

Naturally this depends entirely on BT range.  Given that a car may be parked in a garage or some distance from your phone, it may not do what you need. It should however work when close to the car and save you from opening the car to check. 

It would be much better if Toyota could add Battery state to their App. 

[Gray86]

My dad has a 6 month old 2.0 CHR, and (like me) uses his CTEK MXS 5.0 charger on occasion to keep the Battery topped up. He charges it before going away (for 2+ weeks) and comes back to a fully functioning 12v Battery. 
 

a CTEK with a top up now & again (especially in winter) is the way to go. 
 

I recon EVs will have the same issue too in future, so a charger is a sensible purchase (circa £70) 

[IT Troll]

On 12/3/2022 at 10:44 AM, Roy124 said:

It would be much better if Toyota could add battery state to their App. 

I asked them to do exactly that. They said they would forward the suggestion onto the engineering team.

With the older Touch2 infotainment system it is possible to access a service screen which includes Battery state. I've not been able to work out how you do this on the newer SmartConnect system.

[rev.roger]

What chargers or jumpers are recommended?