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Rosie60 said:
Mine too won't start. I've been taking it out one a week to get the Sunday paper 2 miles each way. The Ev battery was fully charged last week but I've obviously been quietly reducing the 12v battery. I've borrowed my husbands trickle charger for now (and his car this morning). I suppose more and more of us are going to be experiencing this. Cars these days need driving .
I've purchased a Nono Genius 1Uk charger which has recharged my battery and is now maintaining it..Took my car out yesterday, started first time. I ve accepted that I'm not using it enough and the battery will go flat. Good use of £35.
 

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Alexr said:
Had to lock down for a fortnight due to symptoms, and so I switched off the keyless entry. 17 days today, but when I went out to the car it barely had enough juice to open the wing mirrors, and then it went stone dead. Phoned Toyota roadside assistance and they are coming this afternoon. First problem I have had with it for over 3 yrs.
Update. AA turned up promptly. Tested the battery and (surprise, surprise) decided I need a new battery. Given a choice of buying one off them or trying to find some dealer who would deal with me in this lockdown (who even then may or may not change it under warranty) I opted to let them fit a new one. Cost £120. Bit pricey but job done, and Bosch battery fitted with 5 yr warranty.
 
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Discussion Starter · #23 ·
Alexr said:
Alexr said:
Had to lock down for a fortnight due to symptoms, and so I switched off the keyless entry. 17 days today, but when I went out to the car it barely had enough juice to open the wing mirrors, and then it went stone dead. Phoned Toyota roadside assistance and they are coming this afternoon. First problem I have had with it for over 3 yrs.
Update. AA turned up promptly. Tested the battery and (surprise, surprise) decided I need a new battery. Given a choice of buying one off them or trying to find some dealer who would deal with me in this lockdown (who even then may or may not change it under warranty) I opted to let them fit a new one. Cost £120. Bit pricey but job done, and Bosch battery fitted with 5 yr warranty.
Oh noooo!!! Did you not read my earlier post in this thread Alex, you contact toyota uk first, they then send AA round, assess the battery then Toyota UK will arrange AA to fit under your warranty, due to dealers being shut. I did that and got mine all under warranty
 

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Having just joined the flat battery brigade with my hybrid CHR, I too am mighty unimpressed with an expensive car that is unable to be left for two weeks - good job it is on my drive and not in an airport car park. We never had this problem with any of the Lexus cars we owned from 2010 to 2018.

Equally unimpressive is the response from Toyota and from the Dealer (Motorline Worcester).The dealer it seems is more than happy to chat about me buying another car but not about resolving the problems with the 18 month old one I have so I doubt I will buy another Toyota and absolutely not any car from Motorline! Toyota too have been most obstructive and I have been left to my own ingenuity to overcome this fault.

After two weeks of non use it failed to start, I got in with the key and found with a multmeter the battery at 6.8 volts, falling to 4.7v the following day. I jump started it easily enough with a battery booster pack and the battery charged at 14.4v, adequate given its use i suppose but not impressive, dropping back quickly to 12.1v after half an hour on charge and a few minutes off charge.

As there is no alternator per se I assume it charges via transformer from the traction battery, but I wonder at what amperage and therefore how long it would take to fully recharge a flat 12v battery, if indeed the electronic gubbins would allow it to ever fully recharge rather than reach a level deemed 'adequate'?

So no idea how long to run the engine, indeed it does it need the engine at all as it is battery to battery and rises to 14.4 v with the engine switched on but not running?

To my mind it seems worth having the engine running to maintain the traction battery charge level - or am I wrong?

What voltage would the 12v battery need to drop to to prevent the recharging process from recovering it enough to start the car?

I've been around cars for 60 years but have a lot to understand about how hybrids work and my faith in Toyota as a reliable and trustworthy brand has taken a severe beating this week.

It's been many a year since I neede to carry a spare battery - and the cars then were a lot older and a lot easier to understand!
 

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I have been advised that 20 mins (either parked on the drive or driving round) once a week is sufficient to keep the battery charged..
 

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I am a bit puzzled, if you leave car on drive with engine on for 20 minutes it will surely switch to electric mode - if that's the case will the battery still be charging ? I know the hybrid battery charged the 12v one just unsure if it would stop charging if petrol engine stopped to preserve the hybrid battery.
 

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My feeling is that the 12v battery charges from the traction battery regardless of whether the petrol engine is running or not and that the petrol engine only cuts in to keep a reasonable charge in the traction battery when that drops below a certain (unknown) point?

As it is a 45ah 12v battery it would be helpful to know the charge rate but as it only charges at 14.4 V I suspect that it it is not very high?

But I could be wrong!!
 

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You are right, the 12v battery gets charged automatic from the HV battery.. but only if the green READY light is on and selector is not in N(eutral).

Measurement of battery when car is OFF:
Below 11,5 volt the electronics can get errors and/or the hybrid part cannot start fully.
12,0 to 12,5v : Normal

Measurement with green READY light is on :
Between 13,8 and 14,1volt is normal and your battery get charged by the HV battery.
 

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So once the 12v battery drops below 11.5v the HV battery cannot cut in to replenish it and an external power supply is required to kick the 12v battery back up?

With my 12v battery dropping to under 5v I seem to have been fortunate that I have not spotted any errors, but my experience of lead acid batteries over the years is that dropping much below 11v can often be terminal, or at least lead to premature, often out of warranty, failure.

My battery is a Mutlu (never heard of 'em!!) 45AH Calcium flooded
 

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Based on Toyota technical service direction:

Turn the power switch off and turn on the high beam headlights for 30 seconds. This will remove the surface charge from the auxiliary battery. Measure the auxiliary battery voltage.

Condition: 20°C (68°F) Power switch off.

Specified Condition: 12.0V or higher
Auxiliary battery is OK

Specified Condition: 12.0V or less
Recharge auxiliary battery.

Charge Method Charging Current:

Normal: Below 5 A
Quick: Below 15 A
 

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All information gratefully received, thanks Timur, the better I understand it the better I can deal with it.
It is generally accepted that when a 12v car battery is at 12v it is 75% depleted so I am surprised by Toyota's words that 12.0v is enough?
As I understand it a fully charged 12v battery should show around 12.6 to 12.8 v, and personally I am not happy with anytghing less that 12.5v.
I also understand that a Calcium battery requires a charging voltage of 14.8v and mine charges at 14.4v
Does anyone know the charging current from HV traction battery to 12v battery as from that it can be estimated the duration that a re-charge is required?
It seems to me that there may be some design shortcomings with this system, or at the very least inadequate information from Toyota?
 
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Discussion Starter · #32 ·
AA guy told me to just leave it in ready mode and engine will come on and off as required and that's all just keep it on ready for 20 mins on the drive.
I know nothing about car engines, 40 odd years driving and never until now had to
 

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Charlie19 said:
All information gratefully received, thanks Timur, the better I understand it the better I can deal with it.
It is generally accepted that when a 12v car battery is at 12v it is 75% depleted so I am surprised by Toyota's words that 12.0v is enough?
As I understand it a fully charged 12v battery should show around 12.6 to 12.8 v, and personally I am not happy with anytghing less that 12.5v.
I also understand that a Calcium battery requires a charging voltage of 14.8v and mine charges at 14.4v
Does anyone know the charging current from HV traction battery to 12v battery as from that it can be estimated the duration that a re-charge is required?
It seems to me that there may be some design shortcomings with this system, or at the very least inadequate information from Toyota?
You're welcome. Yep, everything above 12V is OK as per repair instructions. Obviously 12V hybrid circuit is a little bit different, that's why toyota put 45 Ah auxiliary battery.

But, also, as per repair instructions, when replacing the auxiliary battery, use a new auxiliary battery of the same dimensions with a capacity of 51 Ah or more at a 20-hour rate.
 

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@Charlie19

This might be the answer on your question, a very good presentation of Prius 12V charging system which is the same the hybrid CHR has. Actually, presenter just stick with repair instructions.

 

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Timur said:
@Charlie19

This might be the answer on your question, a very good presentation of Prius 12V charging system which is the same the hybrid CHR has. Actually, presenter just stick with repair instructions.

Bit long-winded, but very interesting. Makes me think that they missed a trick by not thinking through the situation where the vehicle is not used for a while and the aux battery runs out. If that happens you have loads of charge in the drive battery, but you can't switch on the car to get it to charge the aux battery. Some kind of simple override (eg button you can press) to temporarily switch on the dc convertor to get enough charge into the aux battery to enable the car to power up to ready mode would prevent all the problems so many of us have had with the battery during the lockdown.
 

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Alexr said:
Timur said:
@Charlie19

This might be the answer on your question, a very good presentation of Prius 12V charging system which is the same the hybrid CHR has. Actually, presenter just stick with repair instructions.

Bit long-winded, but very interesting. Makes me think that they missed a trick by not thinking through the situation where the vehicle is not used for a while and the aux battery runs out. If that happens you have loads of charge in the drive battery, but you can't switch on the car to get it to charge the aux battery. Some kind of simple override (eg button you can press) to temporarily switch on the dc convertor to get enough charge into the aux battery to enable the car to power up to ready mode would prevent all the problems so many of us have had with the battery during the lockdown.
True, that would have been great and, not an engineer but shouldn't be that hard to do for them.
 

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I bought a battery moniter fron Lldl back end of last year, i did put a post on here at the time.
Very good. Bluetooth link to a phone app so you can connect from in the house, admittedly not a huge range. Car parked on driveway next to house, connects ok.
Gives battery capacity and voltage of the auxillary underbonnet battery.
Have been locking the car on the metal car so not alarming the car, less drain on the battery.
 

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My thoughts exactly!

"Makes me think that Toyota missed a trick by not thinking through the situation where the vehicle is not used for a while and the aux battery runs out. If that happens you have loads of charge in the drive battery, but you can't switch on the car to get it to charge the aux battery. Some kind of simple override (eg button you can press) to temporarily switch on the dc convertor to get enough charge into the aux battery to enable the car to power up to ready mode would prevent all the problems so many of us have had with the battery during the lockdown".

Sounds simple enough to me?

Very informative video for which I am very grateful, thanks.

For most of us without the designated test gear a few numbers stand out that can be easily checked with a basic multi meter.
The resting voltage of the 12v battery was shown as 12.83v falling to 12.53 with the headlights on, rising back to 10.74v with the headlights off which is more or less what I would expect from any sound normal battery.
The dc to dc charging voltage between 12.5 to 15.0v with an absolute maximum charging current of 10.0 amps, which gives an absolute minimum theoretical charge time for a 45ah battery of 4.5 hours from flat to fully charged - but almost certainly a lot longer time in the real world.

All of which begs the question - how long does the charging system need to be on for each week to maintain a fully charged 12v battery given that there is probably a low current use all the time to maintain things like, alarm, keys and unlock facility, ECU memory, radio memory etc?

It would be good to get some input from the technical guys at Toyota?
 

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Hi - quick question. Like a lot of people, my battery has also died. Unfortunately my car is in our garage. In order for me to jump start it, is there a way to disable the parking brake so I can push it out of the garage so I can access the battery and attach jump leads? might be an obvious question so apologies if it is.

Tried googling it but doesn't seem to be anything about disabling it when you have no power.

any help appreciated. Thanks,

Ken
 

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My understanidng is that you don't need a high current as you would for a conventional starter motor to wake up the traction battery enough for it to bring the car's 12v system back to life so would an extended jump lead reach if you can borrow more leads, or if you can get access to a booster pack, even a low power one, or maybe connect a battery charger to your 12v battery?
Sorry I am not an expert - other than at finding ways to circumvent poor design!
 
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