Battery Tech x 3 That Works

SH20 · January 11

It's true I have never given a second thought to starting any of the 8 hybrid cars we have owned as a family, 6 of which were mine, all Lexus variants.

So when I experienced a failure to start on the very car I had always aimed to own you can appreciate my total surprise when my LS500h didn't fire up 5 days ago which needed the AA's assistance.

Over the last 5 days I have come to understand completely that the auxiliary 12 volt Battery is constantly dropping in voltage and loses power when doors, boot lid are opened, when interior lamps come on etc etc and the hybrid system doesn't get the chance to replenish the battery's reserve. Also the battery standing voltage should be 12.6 volts and when the car is running it should be 14.4 volts or very close to that.

I haven't used the LS any less or more than the other 5 Lexus Hybrids. The first Yaris Hybrid the wife owned and her current Yaris is used every day and often for short journeys but to date no issues concerning a flat 12v Battery. I will now keep my eye on it, although the battery's location under the rear seat is hardly convenient.

I now know that regular charging will keep the 12v Battery alive so hard wiring my CTek Battery conditioner to the Battery will make it a simple process going forward.

A jump pack kit for emergency use and a simple Battery volt tester to check the standing and running voltage periodically are in the car at all times now. The standing and running volts of my Battery are correct so for the moment I have no need to replace the Battery which Lexus Hull quoted £220 fitted and incl VAT.

Unless I am wrong perhaps a member can confirm that the jump pack +post often found under a fuse box cover under the bonnet along with any suitable negative ground point can be used to charge a 12 volt Battery if the same contact points can be used to jump start a car. I ask because the Yaris 12v Battery is under the rear seat squab and not easy to get at.

In some respects I'm glad I have experienced the issue of a Battery losing it's power which allowed me to learn what happens when it's a Hybrid vehicle.

Spacewagon52 · January 11

Just remember, the big NO! NO! is that you can't jump another car with your hybrid!

SH20 · January 11

Ooh! didn't know that. So only a non hybrid car can be used to jump a hybrid car if you were using old fashioned jump leads. I wonder what would happen? Any thoughts on my question?

Unless I am wrong perhaps a member can confirm that the jump pack +post often found under a fuse box cover under the bonnet along with any suitable negative ground point can be used to charge a 12 volt Battery if the same contact points can be used to jump start a car. I ask because the Yaris 12v Battery is under the rear seat squab and not easy to get at.

MLW · January 11

On my Prius when the 12v Battery started to go out, the wipers went wacky, the lights on the dash went crazy, and the car alarm when odd. New Battery....all was back to normal.

Modern cars and hybrids are very sensitive to a good strong 12v Battery. Even the power steering on some FIATs will go wonky if the Battery is iffy.

Never jump start a hybrid, the electrics will blow out and cost a fortune. Hybrids work by the 12v Battery telling the computer to start the engine. You cannot and must not 'shock' it into action.

scythe · January 12

Yes, there appears to be a bit of confusion here. The engine in a LS500h is started using the traction Battery. The car has two motor/generators. The front motor/generator is used to start the engine when required. (It also does some regeneration when slowing down or hill-descending).

All the energy for this comes from the HV traction Battery.

The 12V Battery is never required to produce the 100s of amperes that other cars, including most hybrids, require for starting. It powers all the usual low voltage requirements in the car, and is constantly recharged from the traction Battery when the hybrid system is running.

If the 12V Battery discharges then the electronics in the car can't do anything, including operating the front motor/generator. However, it doesn't need the very high current boost that those little jump start devices provide - and I'd be scared to use one in case the high voltage they could produce would damage electronics in the car.

However, if the traction Battery discharges, you're stuffed! Here's what the user manual has to say:

Charging the hybrid Battery (traction battery)

As the gasoline engine charges the hybrid Battery (traction battery), the Battery does not need to be charged from an outside source. However, if the vehicle is left parked for a long time the hybrid Battery (traction battery) will slowly discharge. For this reason, be sure to drive the vehicle at least once every few months for at least 30 minutes or 16 km (10 miles). If the hybrid Battery (traction battery) becomes fully discharged and you are unable to start the hybrid system, contact any authorized Lexus retailer or Lexus authorized repairer, or any reliable repairer.

Back to me ...

For me, I'd rather accept that a six year Battery needed replacing, rather than hardwiring in a charger (which might be a problem anyway - the user manual says to disconnect the ground connection before attempting to recharge it).

The price that Hull has suggested would be about right for a top quality start/stop Battery - the sort that most toyota/lexus hybrids would require, because that Battery would be constantly starting the engine. However, it's not a necessary or appropriate choice in this case. (A Yuasa Battery for about £100 or so is available, and Halfords would fit one for £20.) They probably haven't seen enough 500hs to have realised! (That's me being kind about a Lexus dealer)

: o )

ColinBarber · January 12

11 hours ago, SH20 said:

Unless I am wrong perhaps a member can confirm that the jump pack +post often found under a fuse box cover under the bonnet along with any suitable negative ground point can be used to charge a 12 volt battery if the same contact points can be used to jump start a car. I ask because the Yaris 12v battery is under the rear seat squab and not easy to get at.

Yes you can use that connection point. It's better to have it directly connected to the Battery but no problem using the jump point.

Thackeray · January 12

11 hours ago, MLW said:

Never jump start a hybrid, the electrics will blow out and cost a fortune. Hybrids work by the 12v battery telling the computer to start the engine. You cannot and must not 'shock' it into action.

It's true to say that you shouldn't attempt to help someone jump start a broken down conventional car from your hybrid Lexus or Toyota. The hybrid 12v electrics aren't designed for the heavy load produced when the conventional car's starter motor draws on the hybrid car's circuitry. Having said that, I seem to remember someone reporting that they had done this without any problems but the possibility of expensive damage is probably too great to take the risk.

By contrast, if your hybrid car's 12v Battery is flat, you can jump start the car from a conventional car in the usual way. The manual describes how to do this and there's a convenient jump lead connection point under the bonnet so that you don't have to connect directly to the Battery.

I was once asked to help someone start a conventional car by jump starting from my hybrid Lexus. I said I couldn't do that but I had a cheap Chinese jump start pack we could use. I connected it up and he tried the starter motor. The starter motor didn't turn but the jump start pack started to smoke and looked as if it was about to burst into flame. I decided not to buy another cheap Chinese jump start pack after that experience.

SH20 · January 12

Kevin, your take on this has created more questions than answers for me. When I pulled the handle to enter the car I noticed the mirrors were slow to fold back but the car's door locks opened but there was nothing when I pushed the button with my foot on the brake. I got out and tried to lock the car but nothing.

If the traction Battery on a LS500h starts the car and accepting the 12v Battery read only 3.1 volts when the AA man put his volt meter across the jump pack post under bonnet why did it the car start up immediately when he jumped it with his jump pack. It took a few minutes for flashing warning lights to eliminate/reset themselves and a number of fault codes had to be cleared on his code reader but after a run of 40 mins the car seemed to be back to normal. After charging the 12v Battery the standing voltage was 12.5v and the running voltage was 14.4v.

Isn't the 12 v Battery the power source that energizes the electrical systems in order to enable the traction Battery to take over as well as powering up the usual equipment.

scythe · January 12

Using jumpers will very rapidly bring the emf of the 12V Battery up to something reasonable for the electronics of the car to work. When the electronics work the traction Battery does the work of starting the car. The traction Battery will then also start to charge the 12V Battery. The 12V Battery doesn't do the work of starting the engine. It just activates the hybrid system - and all the electronics and lights and blowers and radio and everything else, just like a normal car.

Incidentally, taking the car for a run won't increase the charging rate of the 12V Battery. There is no alternator. 12V electricity is made from the 310V electricity by the magic of electronics. and if the traction Battery has spare energy it deals directly with this.

: o )

ColinBarber · January 12

1 hour ago, SH20 said:

If the traction battery on a LS500h starts the car and accepting the 12v battery read only 3.1 volts when the AA man put his volt meter across the jump pack post under bonnet why did it the car start up immediately when he jumped it with his jump pack. It took a few minutes for flashing warning lights to eliminate/reset themselves and a number of fault codes had to be cleared on his code reader but after a run of 40 mins the car seemed to be back to normal.

If the Battery was just what we would call flat (e.g. 11+ volts) then you would have been able to connect up a jump pack and 'start' the vehicle almost immediately.

With a heavily discharged or faulty Battery, it will drag down the voltage of the jump pack/battery where the overall system voltage is still too low for the vehicle's electronics to function correctly - it needed a few minutes to build up a small amount of charge in your 12 v Battery before successfully allowing the vehicle to enter Ready mode.

SH20 · January 12

Mmmmm, Still confused about the LS500h starting process but I think what is being said by members is that specifically the front motor/generator starts the engine itself but is dependent on the 12 volt Battery providing the current/power to power up the necessary electronics that enable the traction Battery (Which is not discharged) to start the engine or to get to the READY drive away condition. Then once on the move the 12 volt Battery gets charged from the rear motor/generator or maybe the front one, I wouldn't know.

Is that right Kevin (Sycthe)??

I have been out today and the car started normally during two 13 mile journeys with a 2 hour break between those journeys.

TOMORROW FIRST THING I AM GOING TO CHECK THE STANDING VOLTAGE OF THE 12 VOLT Battery AND THEN I WILL START THE CAR AND CHECK THE RUNNING VOLTAGE OF THE 12 VOLT Battery. IF THE STANDING VOLTAGE IS LESS THAN 12.4 (APPROX 75% CHARGED) AND THE RUNNING VOLTAGE IS LESS THAN 14.5 VOLTS I WILL CALL IT A DAY AND HAVE A NEW Battery FITTED BY LEXUS HULL AS PER THEIR QUOTE OF £220 INCL VAT.

I'm not adverse to spending money, after all I spent £42K on a six year old car but I want to spend it in the belief that I'm changing the Battery because it is necessary rather than the Battery might be on it's last legs.

scythe · January 12

Yeah, that's pretty much it - the only thing is that no motor/generator is used to directly charge the 12volt Battery. The car has an inverter/converter that does a range of things electronically and efficiently, including directly producing 14V dc from the 310V Battery to charge the 12V Battery. There is no generator that directly charges the 12V Battery. (The inverter/converter also increases the voltage to 600 ish volts, and drives the two motor/generators, making AC from the traction battery's DC, and alternately uses AC electricity from the motor/generators,and converts it to charge the traction Battery.

If you do chose the Hull route, why not make them ring Lexus technical, or look on their service manuals, to make sure that they are fitting the correct Battery - find out what the original equipment Battery is, and ask them to fit that?

I'm not trying to give you any grief over this - but the idea of the car is that it looks after itself, and lets you just get in and drive it, and just gives you pleasure! If you're using the car regularly, I'd expect there not to be a problem with this at all. And if the 12V Battery was getting low, I'd expect there to be a message and a bingbong to tell you that you there was a problem, and to start the car to charge it, just like in my old 2007 LS.

: o )

SH20 · January 12

You have a lot of knowledge Kevin and although I don't fully understand all the techno speak I can see the hybrid system has a lot going on and yes I agree I just want to get in the car and press a button and move off.

If my voltage checks lead me to think I need to change the Battery I will make sure the dealer selects the correct Battery. I do suspect the Battery is the original and the parts guy did say everything is driven by the chassis number to ensure the right part is identified.

Interesting you mention a LS460, my very first Lexus was a 2007 LS460 SE-L and of course a conventional V8 petrol without turbos, a truly sublime car which allowed me to enjoy totally trouble free motoring. Bought that from Lexus Carlisle.

One of my previous posts called So Proud would be an understatement opens with a 5 min video of that car just after I sold to a trader in Sheffield if you are interested or maybe you've seen it already.

scythe · January 12

Yes, my last car was a 2007 460 SEL. I got it in 2008, intending to keep it for five years, but by 2012 Lexus had nerfed all of their 460s, and I didn't want a 600, so I just kept on with it till last summer (when it was about 16 years old), and did the swap then. I bought my first LS (LS400) in 1998, then had a couple of 430s, so I've only driven LSs for 25 years. Just for their reliability, comfort and safety there's nothing else I'd want to drive.

I had seen your video. I suspect, though, that you and I have a different approach to the cleanliness of the outside of our cars.

: o )

SH20 · January 13

For me it was the colour, Sienna Red with a caramel coloured interior, not common and I had seen lots of cars before finding that one.

If I could have found a LS500h in Agate with a tan interior I would have been very happy. My LS500 is in Manganese Lustre with the black and Claret interior, pleated door cards with Kiriko Glass, a Lexus Press car originally back in 2017. So much improved in lots of ways in the 10 years between both LS versions. This 12v Battery question is now exhausted for me and I will move on but so grateful for all the help and information the forum members have been willing to share, especially your detailed explanations.

Yes, cleaning cars and keeping them clean is an OCD affliction I suffer from.

RONNIE W HODGEKINSON · January 13

8 hours ago, SH20 said:

You have a lot of knowledge Kevin and although I don't fully understand all the techno speak I can see the hybrid system has a lot going on and yes I agree I just want to get in the car and press a button and move off.

If my voltage checks lead me to think I need to change the battery I will make sure the dealer selects the correct battery. I do suspect the battery is the original and the parts guy did say everything is driven by the chassis number to ensure the right part is identified.

Interesting you mention a LS460, my very first Lexus was a 2007 LS460 SE-L and of course a conventional V8 petrol without turbos, a truly sublime car which allowed me to enjoy totally trouble free motoring. Bought that from Lexus Carlisle.

One of my previous posts called So Proud would be an understatement opens with a 5 min video of that car just after I sold to a trader in Sheffield if you are interested or maybe you've seen it already.

Is The chassis number Of The Lexus Different to the Vin Number And if so where do you locate the Chassis Number is it located under the bonnet lid within one of the information stickers ?

ColinBarber · January 13

3 hours ago, RONNIE W HODGEKINSON said:

Is The chassis number Of The Lexus Different to the Vin Number

It is the VIN.

SH20 · January 13

VIN and chassis number are the same, stamped into the bodywork under a flap in front of the driver's seat and visible in the corner of the front screen as well as on a small black sticker on all 4 doors, bootlid and bonnet which can't be peeled off for security as it just shatters in pieces if you try and remove them.

SH20 · January 13

Kevin, (Scythe) saw a video on YouTube which said wash your car and charge your 12v Battery at the same time in 1 hour.

It was a Yaris, useful as we have one, and basically the car was turned on with the Ready light lit up with all things turned off and the smart key on the drivers seat. The premise was the hybrid Battery would be charging the 12 v Battery even with the engine not running. Turned out over the hour spent washing the car the engine came on for approx 150 seconds in total cutting in and out as necessary and throughout this the 12 v Battery was being charged during the hour he spent washing his car. The chap even said the manual advised to turn the car on and leave for an hour in the Ready mode (car wash not included obviously) and that will charge the Battery to keep it at the right voltage, the engine will naturally cut in and out. Not sure if the engine running is accurate in terms of how many seconds/minutes he calculated his engine ran for.

So, Kevin will this work???

scythe · January 13

Certainly, in a LS500h, that would charge the 12V Battery for the hour.

But why? Why not take the car to Tesco, buy some groceries, and then drive it home? Or any normal sort of journey? And why would someone make a youtube video of this?

2 hours ago, SH20 said:

The chap even said the manual advised to turn the car on and leave for an hour in the Ready mode

Can I just say that the LS manual doesn't have this sort of advice - why not check your own Yaris manual to see if you can find this there?

If you are going to change the Battery then why not lift out (or get a mechanic to lift out) the current Battery, just to see what's written on the side, and then insist on getting one that's just the same?

Then you could try to forget that the car even has a 12V Battery, and just enjoy driving around in it. I recommend a ferry, followed by a nice drive across to the west coast of Ireland and back, with perhaps a week in the middle in a holiday cottage.

: o )

Malc1 · January 17

On 1/13/2024 at 10:29 PM, scythe said:

I recommend a ferry, followed by a nice drive across to the west coast of Ireland and back, with perhaps a week in the middle in a holiday cottage.

brilliant suggestion 👋

Malc

Bluemarlin · January 17

On 1/13/2024 at 10:29 PM, scythe said:

Can I just say that the LS manual doesn't have this sort of advice - why not check your own Yaris manual to see if you can find this there?

I'm not sure that it's advice in the manual. I think it was advice published on the website for keeping the Battery topped up during Covid.

scythe · January 17

8 hours ago, Bluemarlin said:

I'm not sure that it's advice in the manual. I think it was advice published on the website for keeping the battery topped up during Covid.

https://mag.toyota.co.uk/coronavirus-toyota-hybrid-car-maintenance/comment-page-12/#:~:text=We%20recommend%20you%20put%20the,Coronavirus%20(Covid%2D19).

I understand now where the advice came from now!

: o )