12v Battery replaced today under warranty

[Bounce75]

Been having an issue with my 12v Battery the last 6 weeks or so, it has been discharging over the course of a week & on a couple of occasions has actually got so low the car wouldn't start & I had to jump it.

I mentioned it at my service a month ago that it had gone flat & they said they would charge it & asked me see how it performs.

I also decided to keep a check on it myself with my  volt meter. Fully charged & after the charger was taken off it was only showing a voltage of 12.5v, this dropped to 12.2v 24hrs later, 2 days after that it was reading 11.93v, although the car did start at this voltage.

Well after it going flat again last week I asked them to change it as the car is only 2 years old, this was done today under warranty with no argument. The cost to Lexus on the invoice was £225 which seems quite expensive for a 12v Battery to me?

I noticed it has a Toyota branded Battery 12v 45ah fitted so hopefully all will be ok now for a few years.

 

[Inazone]

This is a common problem, my IS300H Battery was replaced in 2019 about 6 months after I bought my car. I decided not to go with the AGM batteries as they are very expensive and I don't believe you get value for money, so I bought a standard Battery which has been performing OK. Although I now monitor my Battery 24/7 via a wemos d1 mini which reports my Battery voltage via mqtt. I've set up warning messages to alert me if the Battery voltage drops too low. I will then stick the CTeck charger on. Why Lexus can't use a standard size Battery I don't know. 

[PaulWhitt20]

£225 is the going rate for this Battery. It is not one you can buy from Halfords and replace yourself. 

[D Johnson]

I am having an issue which may (or may not) be Battery related, opinions differ at my dealer.  My IS is a similar age to yours.  About six weeks ago the car would not start and displayed the red warning message “hybrid system stopped.  Shift to P.”  I could not shift to P as I was already in P.  I eventually managed to start it and wrote it off as some sort of sensor malfunction, but unfortunately this was not the end of it.  The next morning I was late for work because the car again refused to start but this time nothing I tried seemed to work and I had to start scouring the Lexus forums for help.  I eventually started the car by pressing and holding the start button for 15 seconds.  I contacted my dealer and the message from the workshop was that it sounded like the 12v Battery was flat.  They suggested I call roadside assistance so that they could establish the fault.  This was likely because I live 40 miles away and work long hours so could not just drop in to the dealer.  Given that I could now start the car with my trick, I thought breakdown would not come out to me since I was not broken down.  Long story short, I did some more research and decided it was worth buying a CTEK MXS5 charger and duly recond and charged the Battery.  I did not buy a Battery tester but I now think I shall because after everything being fine for a week or two things have started to happen again with the red warning message.  From what I can gather, the 12v Battery has no alternator and is charged from the traction Battery which takes approx one hour of running… 

My question is: if the 12v Battery is never fully charging because my commute is 40 minutes each way, will this cause the Battery to eventually fail, hence my current problems.  It seems this is something of a known issue on these and the Prius going back many years.  Does anyone know a workaround or should I just accept charging the Battery on a regular basis?  

Also Bounce75, what symptoms were you getting as the Battery was discharging?  

[IS300FSPORT]

https://lexuspartsdirect.co.uk/product/lexus-is-phase-3-auxiliary-12v-starter-battery/

Direct from Lexus £145 + postage call it £155.

If you decide to DIY you can potentially save upto £100.

Its a 15 minute job at the most the Battery is in the boot on the left remove the cover & 10mm spanner for the clamp & terminals very straightforward job.

Keep it charged is key if your not using the car regulat use a maintenance charger I use a Noco Genius 5 every 3-6 months. 

 

[Las Palmas]

47 minutes ago, Inazone said:

This is a common problem, my IS300H battery was replaced in 2019 about 6 months after I bought my car. I decided not to go with the AGM batteries as they are very expensive and I don't believe you get value for money, so I bought a standard battery which has been performing OK. Although I now monitor my battery 24/7 via a wemos d1 mini which reports my battery voltage via mqtt. I've set up warning messages to alert me if the battery voltage drops too low. I will then stick the CTeck charger on. Why Lexus can't use a standard size battery I don't know. 

For a Battery inside the car, I would go for a Battery as safe as possible.

https://www.ebay.de/itm/383360062113?epid=14027859607&hash=item59420a52a1:g:H44AAOSwZedeFc0f&amdata=enc%3AAQAHAAAAsOddJPSoQHrWqdKrFKz84JvnDsdS3X2ROD0JOwPEXc8WrjLFqcLMgveZ443QxMGgZIEWo5%2BiM%2FvrramUO%2BCUumaMISWql%2Bb6wXk1%2B1XnAgz%2FtM2n9xB%2BYkNOx3wLO8UavD3BchIJC9jKgBP6609m6fgPlTgNI9NOws77%2FnlkiY6hNyLim2FY%2BUHa7FKi3fVpu8iXQMTTdzB0mqKMSvSx8gGlGGJZ01BfDzddl9hj0gc0|tkp%3ABk9SR8jFs6-eYQ

Pretty sure Toyota get their own batteries cheaper than eBay sellers.

225£ is rather expensive fitting.

 

[Bounce75]

18 minutes ago, D Johnson said:

I am having an issue which may (or may not) be battery related, opinions differ at my dealer.  My IS is a similar age to yours.  About six weeks ago the car would not start and displayed the red warning message “hybrid system stopped.  Shift to P.”  I could not shift to P as I was already in P.  I eventually managed to start it and wrote it off as some sort of sensor malfunction, but unfortunately this was not the end of it.  The next morning I was late for work because the car again refused to start but this time nothing I tried seemed to work and I had to start scouring the Lexus forums for help.  I eventually started the car by pressing and holding the start button for 15 seconds.  I contacted my dealer and the message from the workshop was that it sounded like the 12v battery was flat.  They suggested I call roadside assistance so that they could establish the fault.  This was likely because I live 40 miles away and work long hours so could not just drop in to the dealer.  Given that I could now start the car with my trick, I thought breakdown would not come out to me since I was not broken down.  Long story short, I did some more research and decided it was worth buying a CTEK MXS5 charger and duly recond and charged the battery.  I did not buy a battery tester but I now think I shall because after everything being fine for a week or two things have started to happen again with the red warning message.  From what I can gather, the 12v battery has no alternator and is charged from the traction battery which takes approx one hour of running… 

My question is: if the 12v battery is never fully charging because my commute is 40 minutes each way, will this cause the battery to eventually fail, hence my current problems.  It seems this is something of a known issue on these and the Prius going back many years.  Does anyone know a workaround or should I just accept charging the battery on a regular basis?  

Also Bounce75, what symptoms were you getting as the battery was discharging?  

It sounds like a very similar problem to myself, when my Battery went flat it was saying shift into P even though it was in P already, also all the lights were flashing inside & outside the car.

I was lucky enough to have a spare Battery from my wife's VW Polo that I used to connect up to my Battery & start my car.

I had no symptoms at all as it was discharging only when it finally went flat which was less than week.

I would push you dealer to change the Battery while it is still under warranty if I was you.

You could buy a cheap volt meter just to check the voltage & record it to show the dealer, luckily I already had a Fluke multi meter from work that I used to confirm my fears.

[D Johnson]

Thanks, this is very interesting given the age of our cars and the fact that our troubles both started about 6 weeks’ ago…. I also had some flashing lights.  

[Las Palmas]

Cold weather is not good for batteries. Happily it is not an EV.

[Bounce75]

1 hour ago, D Johnson said:

Thanks, this is very interesting given the age of our cars and the fact that our troubles both started about 6 weeks’ ago…. I also had some flashing lights.  

Maybe a bad batch of batteries from that year?

My problems started before it turned cold, plus it is parked in the garage most of the time so I don't think cold is the issue.

[Herbie]

No one really knows why Toy/Lex decided on such small capacity batteries but the two main theories are:

1. The cost of the Battery itself. A conventional starter motor takes upwards of 300A to crank the engine, but a hybrid only takes 20A to boot the computers and get the car into READY mode, so a smaller Battery at lower cost will do the job.
2. A physically smaller Battery weighs less, which means that fuel consumption will be less, which in turn means better for the environment and the ever-tighter 'green' targets being brought in by the world's governments. Might sound silly but when you consider the thousands and thousands of batteries per year, it could add up to a considerable sum.

During the first Covid lockdown the advice on Toyota's website was to put the car into READY mode for at least 60 minutes per week to keep the 12V Battery topped up. It seemed to work but it wasn't ideal.

@D Johnson Now that we're into bad weather season I'm not sure if 40 minutes each way is going to be enough to keep the Battery in good condition; not when you take increased usage of lights, heaters, heated screens etc., into account as well. If you put the car in a garage overnight, I'd be inclined to keep it on a trickle charger. Even if you don't have a garage but just keep it on the driveway overnight, it would be easy enough to keep the trickle charger in the house, drill a hole through the wall and feed the 12V wires through and terminate them in a waterproof box on the outside wall. You could then make a permanent connection to the Battery and use some sort of plug/socket arrangement whereby you just pull the car onto the driveway each night and plug it in.

There is a very rough calculation that you can use to see how long the 12V Battery will last before going flat but you have to make so many assumptions that I really don't think it's worth the effort.

First thing to understand is that every time it goes flat it sustains a small amount of damage and so its capacity goes down a bit each time.

Secondly, all cars draw a quiescent current in order to keep things like the clock, the radio presets, the seat memory and so on, alive. Rule of thumb is that about 50 to 70mA (0.05 to 0.07A) is considered 'normal'.

We'll assume a brand new and fully charged Battery and, being as it was mentioned above, a capacity of 45Ah. This means that it should supply 45A for one hour, or 22.5A for two hours and so on, so it'll take:

45Ah / 0.05A = 900 hours
900 hours = 37.5 days
37.5 days = 5.3 weeks

to go from fully charged to fully flat if the car is just left standing doing nothing. However, for the purposes of starting the car, it will be useless for that long before it becomes fully flat.

[D Johnson]

1 hour ago, Herbie said:

No one really knows why Toy/Lex decided on such small capacity batteries but the two main theories are:

1. The cost of the battery itself. A conventional starter motor takes upwards of 300A to crank the engine, but a hybrid only takes 20A to boot the computers and get the car into READY mode, so a smaller battery at lower cost will do the job.
2. A physically smaller battery weighs less, which means that fuel consumption will be less, which in turn means better for the environment and the ever-tighter 'green' targets being brought in by the world's governments. Might sound silly but when you consider the thousands and thousands of batteries per year, it could add up to a considerable sum.

During the first Covid lockdown the advice on Toyota's website was to put the car into READY mode for at least 60 minutes per week to keep the 12V battery topped up. It seemed to work but it wasn't ideal.

@D Johnson Now that we're into bad weather season I'm not sure if 40 minutes each way is going to be enough to keep the battery in good condition; not when you take increased usage of lights, heaters, heated screens etc., into account as well. If you put the car in a garage overnight, I'd be inclined to keep it on a trickle charger. Even if you don't have a garage but just keep it on the driveway overnight, it would be easy enough to keep the trickle charger in the house, drill a hole through the wall and feed the 12V wires through and terminate them in a waterproof box on the outside wall. You could then make a permanent connection to the battery and use some sort of plug/socket arrangement whereby you just pull the car onto the driveway each night and plug it in.

There is a very rough calculation that you can use to see how long the 12V battery will last before going flat but you have to make so many assumptions that I really don't think it's worth the effort.

First thing to understand is that every time it goes flat it sustains a small amount of damage and so its capacity goes down a bit each time.

Secondly, all cars draw a quiescent current in order to keep things like the clock, the radio presets, the seat memory and so on, alive. Rule of thumb is that about 50 to 70mA (0.05 to 0.07A) is considered 'normal'.

We'll assume a brand new and fully charged battery and, being as it was mentioned above, a capacity of 45Ah. This means that it should supply 45A for one hour, or 22.5A for two hours and so on, so it'll take:

45Ah / 0.05A = 900 hours
900 hours = 37.5 days
37.5 days = 5.3 weeks

to go from fully charged to fully flat if the car is just left standing doing nothing. However, for the purposes of starting the car, it will be useless for that long before it becomes fully flat.

Thank you, Herbie, for that comprehensive and extremely helpful reply.   

[route66]

13 hours ago, D Johnson said:

My question is: if the 12v battery is never fully charging because my commute is 40 minutes each way, will this cause the battery to eventually fail, hence my current problems.  It seems this is something of a known issue on these and the Prius going back many years.  Does anyone know a workaround or should I just accept charging the battery on a regular basis? 

This assumes that a flat 12v Battery is a normal everyday thing but it's not. If your 12v Battery is regularly flat, then:

* It's old, can't hold a charge and needs to be replaced (n/a for you)

* It's new, can't hold a charge and is probably faulty

* There is something draining the Battery

* You regularly use accessory mode and sit in the car with the lights/radio on - all of which draw from the 12V Battery if you haven't started it up fully. Top tip: start it fully and leave the engine to kick in and out as it desires. This does not draw from your 12v Battery

The problems you refer to with the Prius and other Toyota hybrids are caused by one of the above. If you're used to sitting in your turbo diesel (with comparatively huge 12v battery) with the interior and outside lights on listening to the radio then you may be surprised when you encounter a Toyota hybrid for the first time. Even Matt Watson from Carwow had a flat Battery when he tested the new Yaris. The bottom line is, start the car fully if you're doing anything that requires power. If the Battery still goes flat, then you have something hidden drawing power that you need to get checked out.  

 

 

 

 

 

 

 

 

 

 

 

 

 

[ColinBarber]

14 hours ago, D Johnson said:

My question is: if the 12v battery is never fully charging because my commute is 40 minutes each way, will this cause the battery to eventually fail, hence my current problems.  It seems this is something of a known issue on these and the Prius going back many years.  Does anyone know a workaround or should I just accept charging the battery on a regular basis?  

If you commute only one day a week and then don't drive the vehicle at any time for the rest of the week then it may not be enough in the winter but anything more than that any you would be fine (if you have a healthy battery).

 

[D Johnson]

1 hour ago, route66 said:

 

* There is something draining the battery

 

 The only change to the car since last year is that a few months’ ago I disabled the keyless entry system..  I cannot account for the first 10 months of the car’s life but would assume that this is the original battery and c 26 months old.  

[D Johnson]

1 hour ago, ColinBarber said:

If you commute only one day a week and then don't drive the vehicle at any time for the rest of the week then it may not be enough in the winter but anything more than that any you would be fine (if you have a healthy battery).

 

I commute 4-6 days per week.  

[ColinBarber]

23 minutes ago, D Johnson said:

I commute 4-6 days per week.  

Then there should be no issue whatsoever. Sounds like your Battery has suffered an early failure similar to OP.

[Randomizer]

I have still original 12V Battery in my 2015 IS. In last maintenance they checked it and it still charges and holds Vs just fine. Only thing they said is that the voltage is bit low, probably because the Battery is just so old. My drive is mainly short drives, maybe one/two longer drives in a week. And I live in very cold climate zone where winter are long and very cold. Still going to change it probably soonish.

[Mr_Groundhog]

I had my service a few days ago and on the hybrid system check they said it was a bit low, and I know the Battery was replaced in May, then the car was at the dealership until november when I bought it. But still, the Battery isn't even one (full) year old and it came as "low" in the report. Hopefully being inside the garage helps with these frosty days because I'm not using the car as much

[LenT]

2 minutes ago, Mr_Groundhog said:

I had my service a few days ago and on the hybrid system check they said it was a bit low, and I know the battery was replaced in May, then the car was at the dealership until november when I bought it. But still, the battery isn't even one (full) year old and it came as "low" in the report. Hopefully being inside the garage helps with these frosty days because I'm not using the car as much

Do you have a trickle charger?

If you’re able to garage it, then that should solve the problem.

[Mr_Groundhog]

 

13 minutes ago, LenT said:

Do you have a trickle charger?

If you’re able to garage it, then that should solve the problem.

They seem like the car version of Iphone power banks, no? Are there any I could plug in to a regular socket I have in the garage?

[LenT]

16 minutes ago, Mr_Groundhog said:

 

They seem like the car version of iPhone power banks, no? Are there any I could plug in to a regular socket I have in the garage?

I have a CTEK trickle charger and plug that into a regular socket in my garage.

To make life even easier, CTEK sells a connector that you connect permanently to the Battery terminals and simply plug into the lead from the charger.

Check it out on the CTEK site - although it’s entirely possible that other makes are available! 😊

[Mr_Groundhog]

23 minutes ago, LenT said:

I have a CTEK trickle charger and plug that into a regular socket in my garage.

To make life even easier, CTEK sells a connector that you connect permanently to the battery terminals and simply plug into the lead from the charger.

Check it out on the CTEK site - although it’s entirely possible that other makes are available! 😊

that sounds great. You have any links?

[LenT]

56 minutes ago, Mr_Groundhog said:

that sounds great. You have any links?

This is the one I have … MSX 5 Test & Charge.

It comes supplied with two connector leads: simple bulldog clip connectors and the eyelet type that you connect permanently to the Battery posts.

So charging is just a simple matter of exposing the Battery and clipping that eyelet lead to the charger and plugging in the charger to the mains.

You can leave it connected as long as needed because the system protects against overcharging.

https://www.ctek.com/storage/938B6F0FD89110019EA95392D63F8D50B4768D0503F1A5B37A36B3194D394A2F/9857f9c716ec406cbd20b76adb076861/pdf/media/7c4ce0ec9e1749d197faafda62be20f1/MXS_5.0-productsheet-low-EN.pdf

Other versions are available and you can shop around to get the best price from all the usual suspects.  I hope this helps!

[LenT]

I hope this makes it clearer!

Note eyelet connection to the Battery posts.