Another GS 12v Auxiliary battery story

[rsdave]

Seems like a common topic so I thought I'd share my own story. My car is a 2017 GS 450h but with very low mileage (less than 4000 miles).

It appears the previous owner may have allowed the Battery to completely discharge on more than one occasion. The factory fitted Panasonic S65D26L
AGM Battery does not take kindly to allowing it's voltage to drop much below 12v too many times. Doing this too often permanently damages the Battery.

Unfortunately the Lexus warranty appears to specifically exclude the 12v aux Battery, at least here in the UK.

Seems like mine has bitten the dust,  I was first alerted to this as the car would open up, but would not go into READY mode. You'll also get a myriad of system failure messages on the dash. I already had a CTEK MXS 5.0, a charger specifically designed for AGM batteries so I recharged it. The Battery lasted about a week before it was dead again. 😬

I took the Battery out of the car. It's actually quite straightforward, all you need is 10mm spanner and undo one nut and two bolts which secure the Battery bracket.

First make sure that the car is turned OFF. It's probably wise to leave the driver's door open ajar and keep your key with you, don't leave it in the car (in case the alarm goes off when you reconnect the Battery, it didn't happen in my case but the Owner's Manual says it's a possibility.)

You also need to undo the the two large power cables, starting with the negative one FIRST. You also need to remove the water drain tube (just pops out) and unclip the Battery temperature sensor. You can then remove the Battery, it has a useful carrying handle which you can use to gently remove it from the car (it's heavy-ish, so be prepared!).

With no possibility of parasitic load as it's now off the car, I recharged it again, using the MXS 5.0 in AGM mode. This completed all the way up to Step 7 (which is 100% charged/float stage) but upon disconnecting the charger and allowing the Battery to 'rest' (in other words, nothing connected) the Battery measured 12.7 volts using my digital volt meter). That is not bad, but still not quite right. The fully charged AGM Battery should read just a smidge over 13 volts when fully charged).

I then left it to 'rest' overnight, by all accounts the Battery should still read around 13 volts, but, unfortunately not, as you can see in the attached photo the voltage dropped overnight to 10.75 volts. That's a 100% sure sign the Battery is toast. I suspect a shorted cell which is generally unrepairable. (There are generally six cells of 2 volts each in a car Battery which gets you your 12 volts-ish. A shorted cell accounts for the 2 volt drop). 

I know it's possible to fit an aftermarket Battery but with my car being such low mileage and original I opted for a replacement S65D26L. 

At the moment LexusPartsDirect are doing it on Special Offer for £215.39 inc VAT which is cheaper than my local dealer could do it for, and of course it's delivered right to your door within 72 hours. Lexus GS Phase 4 Auxiliary Battery | 28800-31410 | Lexus Parts Direct

It ships in a cardboard box inside another cardboard box, I advise you open it outside, as one of the plastic bags is full of an absorbent material, best described as wood chippings or cat litter, assumedly to absorb any leakage should the package be damaged, but as it was the packaging is super strong and mine arrived undamaged.

The Battery does come about 90% charged, but before fitting I charged it with the MXS 5.0, again using the AGM specific mode. Once that finished, I allowed it to rest overnight and was pleased to see it measured just over 13 volts in the morning.

Fitting was of course reversal of removal, and nothing odd happened during re-connection, a few settings like the auto-fold in mirrors and HUD position were reset to defaults, but everything else was exactly where it was previously.

I will probably take the failed Battery to Halfords, as apparently they will take and recycle old car batteries even if you're not making a purchase. Local council tips generally take them as well.

Hopefully someone will find this guide useful, it should apply to all 2012-2018 GS's, and possibly the previous ones too.

Dave.

[Herbie]

15 minutes ago, rsdave said:

I will probably take the failed battery to Halfords, as apparently they will take and recycle old car batteries even if you're not making a purchase. Local council tips generally take them as well.

Take it to a scrap metal dealer - I got a tenner for the last one I took.

[KayCee]

yes dave i had exactly the same problem with mine got the car home on the saturday didnt start it on the sunday as it was 2 pints and dinner at local club.

I went to start it on the monday to go into town but Battery was flat as pancake i contacted tonbridge wells  who was very apolagetic  as i tried when i bought the car to specifficaly check that the 12 v Battery was in order and was assured that it was but it was not.

but the outcome was ok as they told me to go to lexus hull and they will fit me a new Battery so all was well

the moral is if these cars are left on forecourt and the Battery goes flat as you say the Battery is toast buyers beware.

It also happened on the gs i bought at sidcup but they changed Battery on the spot for me

Hope car running ok apart from yr Battery problem.

Robert

 

[Shahpor]

Excellent post Dave, I am sure it will be useful to many of us GS owners 👍

[rsdave]

5 hours ago, KayCee said:

yes dave i had exactly the same problem with mine got the car home on the saturday didnt start it on the sunday as it was 2 pints and dinner at local club.

I went to start it on the monday to go into town but battery was flat as pancake i contacted tonbridge wells  who was very apolagetic  as i tried when i bought the car to specifficaly check that the 12 v battery was in order and was assured that it was but it was not.

but the outcome was ok as they told me to go to lexus hull and they will fit me a new battery so all was well

the moral is if these cars are left on forecourt and the battery goes flat as you say the battery is toast buyers beware.

It also happened on the gs i bought at sidcup but they changed battery on the spot for me

Hope car running ok apart from yr battery problem.

Robert

 

Hi Robert,

Glad to say 100% perfect with the Battery replaced.

Unfortunately the previous owner was unaware that you can't leave the car for extended periods without maintaining the Battery. Now that it's been replaced, I'll be sure to regularly check it.

Cheers,

 

Dave.

[royoftherovers]

8 minutes ago, rsdave said:

Hi Robert,

Glad to say 100% perfect with the battery replaced.

Unfortunately the previous owner was unaware that you can't leave the car for extended periods without maintaining the battery. Now that it's been replaced, I'll be sure to regularly check it.

Cheers,

 

Dave.

No real need to keep checking Dave. Put it in READY mode as per the Handbook.😉

[MikeTangoWhisky]

20 minutes ago, rsdave said:

Hi Robert,

Glad to say 100% perfect with the battery replaced.

Unfortunately the previous owner was unaware that you can't leave the car for extended periods without maintaining the battery. Now that it's been replaced, I'll be sure to regularly check it.

Cheers,

 

Dave.

Dave,

In extremis how long can these cars be left for before this occurs? This might seem like a "how long is a piece of string" question but I'm currently considering a 450H but work abroad i.e. left standing for periods of between three and six weeks.

Cheers.

[royoftherovers]

11 minutes ago, MikeTangoWhisky said:

Dave,

In extremis how long can these cars be left for before this occurs? This might seem like a "how long is a piece of string" question but I'm currently considering a 450H but work abroad i.e. left standing for periods of between three and six weeks.

Cheers.

I`ve left mine on several occasions attached to a Solar Charger via the OBD11 Port for 3 months without problems.

However, I advise you to buy a CTEK MX5 Charger to maintain your Battery in peak condition whilst you are away Mike TW. And don`t forget to read the Handbook.😉

[bigglesfllesundone]

The latest Lexus Select used car warranty excludes the 12v Battery.

However on Listers website and other places there is reference to presumably, the previous, pre-relax warranty.

“All Approved Pre-Owned Lexus come with a comprehensive one year Lexus warranty with unlimited mileage cover. This even includes wear and tear cover for batteries, exhausts and wiper blades for three months or 3,000 miles (whichever is sooner).”

It may be worthwhile looking at warranty wording if it is within 3 months of buying car.

Hope this is helpful.

[Herbie]

2 hours ago, MikeTangoWhisky said:

Dave,

In extremis how long can these cars be left for before this occurs? This might seem like a "how long is a piece of string" question but I'm currently considering a 450H but work abroad i.e. left standing for periods of between three and six weeks.

Cheers.

You're correct, it is very much akin to 'how long is a piece of string' but purely for your information and interest, here's a theoretical example.

My RX450h has a 51Ah Battery, which means that it could supply 51A for 1 hour or 25.5A for 2 hours and so on. We'll assume for the purposes of this example, that it is brand new and fully charged.

The Battery will always be 'active' even in the middle of the night, as it has to supply things like the alarm, the clock, the radio presets and suchlike. This is called the quiescent current draw and although I haven't seen a figure quoted for Lexus cars, general rule-of-thumb wisdom says that around 50mA (0.05A) is considered to be 'normal.'

51Ah / 0.05A = 1,020 hours or 42.5 days or 6.07 weeks from fully charged to fully discharged.

However, reality is somewhat different when you take into account the age of the Battery, the state of charge, the diminished capacity that comes with age, and also the fact that the Battery will no longer be able to start the car long before it becomes fully discharged.

I think you'll agree that it's not an exact science?

[MikeTangoWhisky]

12 hours ago, Herbie said:

You're correct, it is very much akin to 'how long is a piece of string' but purely for your information and interest, here's a theoretical example.

My RX450h has a 51Ah battery, which means that it could supply 51A for 1 hour or 25.5A for 2 hours and so on. We'll assume for the purposes of this example, that it is brand new and fully charged.

The battery will always be 'active' even in the middle of the night, as it has to supply things like the alarm, the clock, the radio presets and suchlike. This is called the quiescent current draw and although I haven't seen a figure quoted for Lexus cars, general rule-of-thumb wisdom says that around 50mA (0.05A) is considered to be 'normal.'

51Ah / 0.05A = 1,020 hours or 42.5 days or 6.07 weeks from fully charged to fully discharged.

However, reality is somewhat different when you take into account the age of the battery, the state of charge, the diminished capacity that comes with age, and also the fact that the battery will no longer be able to start the car long before it becomes fully discharged.

I think you'll agree that it's not an exact science?

That was certainly more science than I expected on an owners forum. Enlightening none the less!

[rsdave]

14 hours ago, bigglesfllesundone said:

The latest Lexus Select used car warranty excludes the 12v battery.

However on Listers website and other places there is reference to presumably, the previous, pre-relax warranty.

“All Approved Pre-Owned Lexus come with a comprehensive one year Lexus warranty with unlimited mileage cover. This even includes wear and tear cover for batteries, exhausts and wiper blades for three months or 3,000 miles (whichever is sooner).”

It may be worthwhile looking at warranty wording if it is within 3 months of buying car.

Hope this is helpful.

Hi, thanks for that. I did pour over my Lexus warranty document as supplied in March and I am just within 3 months and it does unfortunately specifically exclude any Battery other than the HV traction Battery. (see scans below).
There's also a similarly worded document on the official Lexus site:
Lexus Web Page TC's Dec 2019 (d3rvezpmgp265q.cloudfront.net)

I sadly could not find any reference to a 3,000 mile wear and tear cover clause, so perhaps that's unique to Listers. Shame.

[mercbon]

On 6/14/2021 at 4:40 AM, royoftherovers said:

However, I advise you to buy a CTEK MX5 Charger to maintain your Battery in peak condition whilst you are away Mike TW. And don`t forget to read the Handbook.😉

This. I bought one from 4wheelonline a couple of years ago for my car. It's an awesome charger that helps restore and maintain my Battery in good condition.