is300h battery problems

R Francis · January 6, 2021

i have been having Battery problems during lockdown yesterday car would not go into ready mode kept saying put in park and press star. it was in park i put my tester on the Battery it said 8v i then put trickle charger on and tester read 12.8v 2 hours later it was back at 9v took it back up to 12v but still dose not want to go to ready mode i think the Battery is on its way out its 4 1/2 years old being such a small Battery perhaps its time is up. anyone else had same problem

Herbie · January 6, 2021

Yep, it has gone to Battery heaven as the chart below will show:

You need to use the car more or, given the lockdown, the advice on Toyota's website was to put the car in P and READY mode for 60 minutes per week. The petrol engine will fire up as needed to keep the 12V Battery topped up, but don't leave it unattended because anyone could drive away in it once it's in READY mode - just sit in it and read the paper or something.

royoftherovers · January 6, 2021

26 minutes ago, R Francis said:

i have been having battery problems during lockdown yesterday car would not go into ready mode kept saying put in park and press star. it was in park i put my tester on the battery it said 8v i then put trickle charger on and tester read 12.8v 2 hours later it was back at 9v took it back up to 12v but still dose not want to go to ready mode i think the battery is on its way out its 4 1/2 years old being such a small battery perhaps its time is up. anyone else had same problem

Can it be jump started from another car and then left running or taken out for a 45 minute drive?

Herbie · January 6, 2021

2 hours ago, royoftherovers said:

Can it be jump started from another car and then left running or taken out for a 45 minute drive?

Sadly that wouldn't work John.

When a Battery starts at 12.8V and drops down to 9V within two hours it's definitely breathed it's last gasp - only thing to do now is to replace it.

paulrnx · January 7, 2021

Agreed. BRT.

Jayw13702 · January 7, 2021

if its any consolation I suffered the same issues this week with my Battery, it threw up a whole load of error messages and didn't reply want to ply ball after that.

Spoke to my Lexus dealer and they charged me £136 for a genuine Battery, it was in within 2 days and I fitted it in less than 20 minutes. I didn't lose any settings within the car and the Battery was disconnected for about 10 mins.

Hadrian · February 14, 2021

I have posted this before but it's worth repeating.

When changing the 12v Battery, you need to disconnect the rubber vent pipe from the top left hand side of the Battery

It's just a push fit. Also remove the little plastic elbow from the old Battery, and use on the replacement.

It's easy to miss this if you don't have enough light.

LordByronUK · February 14, 2021

Leave the car on stationery for about an hour to trickle charge the 12v Battery from the hybrid Battery, the time between each engine hybrid recharge cycle will become less and less you'll notice, and this will indicate that your 12v is nice and topped up. If after doing this you still experience problems, then you'll definitely need a new 12v Battery.

Thus happened to me recently, I learnt a lot about how the 12v charging works, and will definitely do things differently in the future (i.e, not turning the car off unless I have to, don't use accessory mode too often for too long, etc, etc) however, I ultimately needed to replace the 12v Battery at the dealership. Good luck!

CypressPhil · February 17, 2021

Had the same issue with my IS300h F Sport (on a '65 plate with the original battery). Did the whole beeping and put into park thing, while all the lights on the dash were flickering. I was worried something was seriously wrong with it until I checked this forum (thanks guys!) and felt great relief when I discovered it was the 12v Battery! Removed the Battery (another visit to the forum needed regarding the little rubber hose, as I'd never seen one of those before - thanks again guys), trickle charged it to full (was down to 11.4 volts before charging); reconnected it and it was fine.

Ran the car for an hour with no issues, apart from the TPMS light came on for a while. Couldn't see any issues with the tyres, so assumed it was due to being disconnected from the Battery for a couple of days. I bought a multi-meter to test the Battery, as I didn't want to get caught out and the voltage is now down to 12.18 volts (4 days after last running the car for an hour, where the Battery should have been fully charged). I'm thinking I should probably replace the Battery, as this seems quite a significant loss of voltage in just a few days. Lexus Norwich quoted £140 for a new Battery. What do you think guys? Just replace it to be on the safe side?

ColinBarber · February 17, 2021

3 hours ago, CypressPhil said:

I'm thinking I should probably replace the battery, as this seems quite a significant loss of voltage in just a few days. Lexus Norwich quoted £140 for a new battery. What do you think guys? Just replace it to be on the safe side?

Sounds like it has lost some of its capacity. If you weren't going to leave it longer than 5 days and would use the vehicle for at least a couple of hours a week then you could probably make do with the one you have for a while, probably until the end of the summer - not ideal really.

If you replace it then you still need to charge the Battery for an hour at least once a week (either by running the vehicle or via a charger) otherwise you will quickly reduce the life of your new Battery.

Get the Battery from Lexus Swindon via courier to save a few £££s, not in stock at the moment though.

https://lexuspartsdirect.co.uk/parts/lexus-is/lexus-is-phase-iii-2013-present/lexus-is-3-engine-service-kits/lexus-is-phase-3-12v-starter-battery/?utm_source=LexusOwnersClubUK&utm_medium=ForumLinks

If you have a pulse charger (CTEK, Noco etc) then you could try a repair cycle on the Battery. It's all a bit unproven if these repair cycles actually do anything most of the time but can't hurt to try if you have one, or can borrow one.

CypressPhil · February 17, 2021

1 hour ago, ColinBarber said:

Sounds like it has lost some of its capacity. If you weren't going to leave it longer than 5 days and would use the vehicle for at least a couple of hours a week then you could probably make do with the one you have for a while, probably until the end of the summer - not ideal really.

If you replace it then you still need to charge the battery for an hour at least once a week (either by running the vehicle or via a charger) otherwise you will quickly reduce the life of your new battery.

Get the battery from Lexus Swindon via courier to save a few £££s, not in stock at the moment though.

https://lexuspartsdirect.co.uk/parts/lexus-is/lexus-is-phase-iii-2013-present/lexus-is-3-engine-service-kits/lexus-is-phase-3-12v-starter-battery/?utm_source=LexusOwnersClubUK&utm_medium=ForumLinks

If you have a pulse charger (CTEK, Noco etc) then you could try a repair cycle on the battery. It's all a bit unproven if these repair cycles actually do anything most of the time but can't hurt to try if you have one, or can borrow one.

Thanks for this Colin. Sadly the car has seen very little use over the past year, so I've certainly not done the Battery any favours. Thanks for the tip about ordering from Lexus Swindon. Think I'll order a new Battery from those guys (and make sure I look after that one). In the meantime, I'll keep the existing Battery going with the help of my borrowed charger! Thanks again.

David lings · June 30, 2021

I have a IS300h (4 years old) and in the first 3 weeks it let me down 5 times with a flat Battery.

I took regular voltage readings indicating the Battery was life expired.

Lexus finally took the car back and after 4 days of checking reported the Battery was faulty.

It took two weeks to procure a new Battery.

Since the new Battery was fitted “so far so good”.

The IS300h maybe a very nice car but I have learnt:

- you never do anything in a Lexus without the car being in “ready” mode,

- a Lexus dealer multi-point pre-delivery inspection is not worth the paper it is written on and,

- never leave home without a “jump starter”.

Hadrian · July 5, 2021

Jump starting a hybrid from a non hybrid car is not a good move. Or offering a jump start to a non hybrid car.

Both can cause expensive damage. Hybrid to hybrid is apparently OK.

serbarry · July 5, 2021

As far as I know you can jump start a hybrid from a non hybrid donor car but not the other way round.

Mincey · July 5, 2021

As posted elsewhere on here, and subsequently printed out and stuck onto the box for my jump leads:

Herbie · July 5, 2021

3 hours ago, Hadrian said:

Jump starting a hybrid from a non hybrid car is not a good move. Or offering a jump start to a non hybrid car.

Both can cause expensive damage.

Only the latter can cause expensive damage if you're unlucky and the last three lines of Mincey's post above sum it up nicely.

First and most important point to note is that the 12V Battery on any car, conventional or hybrid, is only used to get the car started. Once the conventional alternator or the hybrid DC/DC Converter is running, that will supply all the 12V systems and also charge the 12V Battery.

When jump starting, the normal procedure is to start and run the engine of the donor car before attempting to start the recipient car. This is so that the recipient will draw current from the donor alternator (or DC/DC Converter) rather than the donor Battery.*

A hybrid car does not need a lot of current to get it into READY mode or if you prefer, to start the car. In a (very unscientific) test that I did, it would seem that around 20A is more than enough.

A conventional car starter motor can draw upwards of 300A when cranking the engine, which is fine because alternators are designed to supply that demand. However, the DC/DC converter on a hybrid car cannot supply anywhere near that amount of current, which is why a hybrid must never be used to jump start a conventional car.

I think there is some electronic wizardry within the converter to prevent excess current draw from it but if, for whatever reason, that failed, the converter would likely make a huge bang and produce lots of smoke.

There is no danger in using a conventional car to jump start a hybrid, just never try it the other way round.

*Given that hybrids take so little current to achieve READY mode, there is no need to have the engine of a hybrid donor car running and it wouldn't make a difference anyway.

Paul Brooksbank · July 22, 2021

I noticed that Lexus were selling those 20 volt solar chargers via their dealerships earlier this year. Would using one of these necessitate disconnecting the breather pipe?