Low voltage (12V) battery failure Gen4 - some advice please?

[GreenJuice]

First time I have experienced this, having previously owned a Gen2 and Gen3. This current Gen4 had a full service and its first MOT 2 months ago. I went on a 21 day holiday and left the car parked and locked in a garage. I have been away for up to 25 days before but usually leave the car unlocked.

This time, the car display came up with a 12V battery warning and wouldn't start. It was a chilly morning (about 5C). I tried again and the car started wildly flashing its headlights (any of you experienced this?) with another Battery warning and again refused to start. I had an old car trickle charger from my pre-hybrid days. Connected it up (following the instructions on page 157-158 of the User Guide manual); charging at around 4 Amps for 3 hours and the car is now back to normal.

I couldn't find anything that I had left on accidentally. The only difference was that I had locked the car this time, and I have heard that this may use up more charge as the car may be listening out for signals from the key fob (but, I might be wrong about this - any thoughts?).

This has dented my confidence in leaving the car for any period of time of around 3 weeks or more! Especially in an airport car park for example. 

Please, can I ask?:

1. How long have others left their Gen4 unused without experiencing a problem with the 12V Battery?
    1a. Is it possible that my low mileage (<5000 per year) and numerous short journeys in London may be reducing this battery's life?

2. Do any of you keep a portable Battery jumpstarter? 
    I have looked around at various posts on Priuschat and it appears that the Prius only needs a peak current output of 35A to boot up its basic systems & pumps before handing over to the HV battery (which does mean it remains inadvisable to supply current via the cigarette lighter type sockets, as the fuse is rated at 15A). So most of the more expensive portable chargers on the market (rated at 600A or more) appear to be much more than needed for the Prius. I am wondering if any of you have thought this through before and could advise on how best to rebuild my confidence in the car, please?

Many thanks!

 

 

 

[PeteB]

I have a RAVPower 500A/12000mAh compact jump-starter (just search RAVPower in Amazon) in my car.  It comes in a neat case which holds the jump leads, a 12V charging cable and mains charger and fits nicely in the seat-back pocket so it's handy if I can't open the boot (vital if the 12V's flat!).

The 12V Battery died on my last Gen 4 Prius when the car was about 18 months old, which my dealer replaced under warranty without hesitation.  If you locked it with the remote, the Battery would be powering the alarm system as well as doorlock sensors etc.

I never left the Gen 4 more than about 10 days, so didn't have any other problems.  I was told not to drive for a month after a heart scare last year, but a couple of time I sat in it in READY mode for half an hour to top up the 12V Battery.  Obviously, you can't do that if you're away on holiday.

[REMAINDER IS JUST BACKGROUND IF INTERESTED]

Before that I had an old fashioned lead-acid jump starter, bought in 2004 for my Gen 1 Prius. It was quite large and heavy so had to live in the boot.  (Fortunately, the Gen 1 Prius was a saloon and the boot could be opened with the key or a cable release beside the driver's seat, alongside a fuel cap release lever.)

It was more frequently required as the Gen 1 had a higher current drain than later models, and a 35ah battery.  Some members of another group used an ammeter to measure the drain, but we never fully understood why the drain was so high, given the car only had basic remote central locking and no key-less start.  In fact, just leaving the key in the ignition in the off position increased the drain quite a bit.  Leaving it in ACCesssory position would flatten it in  a few hours.

A Gen 1 with a perfect 12V battery, fully charged, and with everything switched off, would be lucky to survive much more than 3 weeks in an airport car park, even when locked manually to ensure the alarm wasn't active.  Gen 2 & 3 did better, with 5 week periods being reported occasionally.

Since the battery drain wasn't fully understood in the very early days, the 12V battery was often already damaged by the time the car was sold, having been flattened during the voyage from Japan, and at least once at the dealer while waiting to be sold.  Only about 1,500 Gen 1s were sold in the UK from 2000-2004, only 60 dealers could handle them, and they were never actively marketed, so they sold very slowly, mostly to people (like me) with a keen interest in such technology.  Once the issue was known, I understand the 12V battery was disconnected during the sea journey.

[GreenJuice]

Many thanks for your helpful response. Hope you are better now after your scare.

[Catlover]

Just this last Monday I posted my experience in the Auris club section to help someone......

I have a Suaoki U3 compact Battery with car leads, currently on Amazon for £39.99. Can be used directly across the Battery in the Auris boot (and Gen3 Prius) or across the Jump Start Point under the bonnet. Charges up using standard Android phone cable, has inbuilt torch that also flashes SOS, and can charge a mobile phone. Fits in trouser/jacket.

I keep it in the pouch behind drivers seat, handy there, accessible if 12v Battery is flat, use key to open driver door, reach over seat, open bonnet, access to jump start point. 
Interesting that Toyota have fitted the 12v battery under the bonnet in Gen4 Prius.

[PeteB]

1 hour ago, Catlover said:

...Interesting that Toyota have fitted the 12v battery under the bonnet in Gen4 Prius.

They've gradually been making the Hybrid components smaller, so finally found room to put it back in the front.

I think I read somewhere that Corollas with the 2 litre engine have it back in the boot, and certainly my RAV4 Hybrid (the engine is 2½ litre) has it back in the boot.

[QuantumFireball]

Some things to consider:

• Is your garage attached to your house, and were the keys left nearby? I've heard this can lead to increased Battery drain if the keys are left in proximity to the car - though I don't know how close this needs to be.
• Turning off the intrusion sensor can reduce Battery drain, obviously with reduced security - not sure if it's an option with the gen 4 (or fitted in your example)

[PeteB]

2 minutes ago, QuantumFireball said:

...Turning off the intrusion sensor can reduce battery drain, obviously with reduced security - not sure if it's an option with the gen 4 (or fitted in your example)

The Gen 4 does have this, and pops a message on the dash every time you switch off with a yes/no choice to disable it.

At a further reduction of security, you can lock with the emergency key or by pressing the lock button on the driver's armrest and closing the door while holding the handle outwards. This will mean the alarm is fully off and the car is not deadlocked so may not be ideal.

[kithmo]

If you have a window in the garage you could attach a solar charger. If you have power in the garage you could attache a trickle charger/battery conditioner like the Ctek which puts the Battery on a float charge once it's topped up.

[GreenJuice]

An update for all who helped me with this original posting last year.

I opted to buy a Suaoki U3 as recommended by PeteB, as it was really compact, looked easy to use and competitively priced. Of course, I kept it handy all last winter and never needed to use it!

This time (today) I tried to start the car after going away and then being caught out with an additional 2 weeks of self-isolation when the rules changed while we were away. Outside temperature around 12C, so a bit warmer than last year.

It was 31 days after the car was last used. It’s last journey was a 2 hour run, so there was a reasonable expectation that the low voltage Battery was topped up on that last day. Car was left in the garage, so no need to set the intruder alarm (as mentioned in the discussion above). Interior lights came on, but as soon as the Start button was pressed, everything went blank (all was silent apart from the usual faint ticking from the engine compartment).

Pulled out the Suaoki U3. It had over 75% of its charge left after the full charge when I first got it and after being kept unused for around 11 months. Followed the jump start the instructions for the first time and the car immediately came to life as soon as the connections were made (MFD screen, interior and exterior lights, etc). The car started normally as it there was nothing wrong and with no error lights flashing.

Disconnected the Suaoki immediately after starting the car, as per the instructions, and then left the car in P mode for 10 minutes (out of the garage!) to allow the traction Battery to feed a bit of charge into the low voltage Battery. The ICE came on for a few cycles in that time. I decided to use a trickle charger to top it up overnight.

So it is looking like:
1. The low voltage battery on my Gen 4 will only last around or just over 3 weeks if the car is left unused.

2. This makes airport parking for any travel longer than around 3 weeks slightly problematic. OK for self-park but not for any ‘meet and greet’ or courtesy services.

3. If in a private garage, any gains from not setting the car alarm may be marginal. I might have got a few extra days by not setting the intruder alarm, but clearly this didn’t make a huge difference.

4. Suaoki U3 worked as it said on the tin (thank you PeteB)! It does not have a trickle charge option, so you can’t use it for that.

Any thoughts or ideas for the future would be most welcome. The car is a 2016 model and coming up to its second MOT soon. I’m wondering if this is only to be expected, or whether I should take the opportunity to get a new 12V battery. For example, I wonder how long these cars can be left in a garage forecourt needing to be started.

[GreenJuice]

My apologies! Credit should have gone to Catlover for the Suaoki recommendation. Thank you.

[GreenJuice]

In response to QuantumFireball’s comment from last year. The keys were hung in an adjacent room around 4m from the car.

[Catlover]

43 minutes ago, GreenJuice said:
Pulled out the Suaoki U3. It had over 75% of its charge left after the full charge when I first got it and after being kept unused for around 11 months. Followed the jump start the instructions for the first time and the car immediately came to life as soon as the connections were made (MFD screen, interior and exterior lights, etc). The car started normally as it there was nothing wrong and with no error lights flashing.
 

You had the same experience as I did when I used it on the wife’s Auris hybrid. Put the Suaoki U3 across the Battery terminals in the boot,  when I got by the time I got into the drivers seat and pressed the start button it was ready to go. That really impressed me. I try to remember to charge the Suaoki every month, especially in the winter months.

[GreenJuice]

I try to remember to charge the Suaoki every month, especially in the winter months.

Thanks again.
Yes, I was pleasantly relieved and impressed with it.

Having only just read the manual again, I note that they recommend not to overcharge it (apparently as it may shorten Battery life), I am guessing by disconnecting as soon as it shows 4 solid LEDs.

I was surprised that mine still had 50%-75% charge after 11 months. That was fortunate, as the manual advises not doing a jump start when the charge is below 50%. Not sure why, but that seems a shame. The box also says it is good for 1000 charge cycles, so even with monthly charging that should be plenty of life.

[Ancient Nerd]

4 hours ago, GreenJuice said:

That was fortunate, as the manual advises not doing a jump start when the charge is below 50%. Not sure why, but that seems a shame. 

 

Mine (VicTsing) says don't use if below 75%. However, I suspect that this is intended to save its Battery when starting an ICE, which need a lot of Battery power to operate the starter motor. The prius only needs very little power to drive the car electronics. So it should be OK down to a very low percentage. 

FWIW I've only used it in anger once, and it worked like a dream. 

[GreenJuice]

Thank you.
Yes, that makes sense now. The Battery level indicators on the unit showed the same both before and after the jump start.

Looks like for a Prius there is little to gain by having a large capacity unit. This one is 8000 mAh.

[Ancient Nerd]

29 minutes ago, GreenJuice said:

Looks like for a Prius there is little to gain by having a large capacity unit. This one is 8000 mAh.

Agreed. Mine is 13,600 mAh, which is massive overkill and waste of money. The only consolation is that it will keep my laptop working for days if necessary 🤔🤔

[PeteB]

53 minutes ago, GreenJuice said:

...Looks like for a Prius there is little to gain by having a large capacity unit. This one is 8000 mAh.

True enough, but I've offered help to a couple of drivers of 'normal' (as in non-hybrid) cars, and it's good to know I won't look like a fool with a puny attempt.

Those I've helped have been astonished to see their cars started with the help of something the size of a VHS tape (although some younger people I meet these days don't actually know what a VHS tape is! - or was!).

[Gerg]

I don't know for sure, but these Battery boosters you have probably run on a few of these, industry standard, 18650 type lithium batteries inside.  They are very commonly used on electric bikes, laptops etc. as well.  Early generation Teslas ran on these cells too!

https://batteryuniversity.com/search/search&keywords=18650/

These are quite cheap, so it is a cost-effective way of getting storage capacity.  If you wanted less power, then the booster would not necessarily be cheaper because it might end up using an unpopular size Battery to do it!  So your 'oversize' boosters are the best value, even if it seems like overkill.

[GreenJuice]

3 hours ago, PeteB said:

(although some younger people I meet these days don't actually know what a VHS tape is! - or was!).

😂🤣. I had to describe the Suaoki U3 to my niece as a 'thick Kindle'!