Intermittent ignition START problem

[DJ Les]

It first happened last night. Turned the ignition key and everything lit up on the dash as normal, then, turning it further to get the READY indication nothing happened. Tried a second time, again, nothing happened. I then switched everything off for a few seconds and tried again and it showed the READY indicator. Everything seemed to work fine after that.

The car has been fine all day today, then, tonight it happened again. I noticed the dash lights on the centre of the dash flashed on and off a couple of times. I thought it maybe the accessory Battery, so, switched off the climate control, the heated seat and auto headlights. Tried twice more and then it showed the READY indicator. I drove a few hundred yards to the next supermarket. On returning to the car I had the same situation and I got the READY indicator the second time of trying.

I'm now very nervous about it and not sure what to do if it fails. Anybody had experience of this and maybe point me in the right direction for a solution? Could it be the 12v Battery under the bonnet not fully charged? The graphics were showing the traction Battery operating as normal.

Anyone got a clue?

[olliesgrandad]

I would certainly be looking at the accessory Battery to start with. I wonder how old the Battery is? 

[Herbie]

Problems like this can almost always be attributed to the 12V Battery.

First thing to do is to give it an overnight charge so that you're starting off with a decent baseline. Check the connections for cleanliness as well as tightness and check the chassis and engine earth straps too. The chart below will give you an indication as to the voltages you could see but you'll need a multimeter to check that. Once in the READY state you should get a reading of around 13.5 to 14.5 to show that the charging system is working properly.

Let us know how you get on - I hate posts where people ask for help and never come back to tell us what the outcome was  

 

[DJ Les]

Thanks Herbs & Les, sounds like we're all thinking the same, 12v Battery.

Since posting, I've just had a quick blast up the country lanes and back with all accessories off, hopefully, putting a decent charge into the Battery.

Are the heated seats a big drain on the Battery? Been using them a lot the last few days (still a novelty to me lol).

Will get a multimeter on the Battery tomorrow as well as checking connections, etc.

Cheers

Les

[Herbie]

6 minutes ago, DJ Les said:

Are the heated seats a big drain on the battery?

Yes and no - sort of  

Any electrical heater is going to be a big power user  but it shouldn't really be a big drain on the Battery unless you're only doing short runs with them on and the charging system doesn't have enough time to replace what they take out.

In a 'normal' car the Battery is only used to start the engine. Once the engine is running and the alternator spinning, it's the alternator that supplies all the car's electrical demands and also recharges the Battery when it can. Our hybrids don't have an alternator but the job still needs to be done and the 12V Battery still needs to be replenished, but in our case it's the traction Battery that does it via a DC/DC converter. The same principle still applies though and you'll still need a good run to do it - short runs with lots of electrical loads will drain the 12V Battery.

[DJ Les]

27 minutes ago, Herbie said:

Yes and no - sort of  

 

Ha ha ha, I kinda said that with tongue firmly in cheek. I already guessed they would be a heavy drain on the Battery. Will have to put thicker boxers on in these cold mornings. 🤣

[DJ Les]

Battery was showing 10.4 volts. With READY light on it was showing 13.5 volts. Currently on charge. It’s a Toyota Battery and looks like a made in Spain sticker, can’t find a date, but, I’m guessing it’s the original Battery.


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[JeffL]

18 hours ago, Herbie said:

Yes and no - sort of  

Any electrical heater is going to be a big power user  but it shouldn't really be a big drain on the battery unless you're only doing short runs with them on and the charging system doesn't have enough time to replace what they take out.

In a 'normal' car the battery is only used to start the engine. Once the engine is running and the alternator spinning, it's the alternator that supplies all the car's electrical demands and also recharges the battery when it can. Our hybrids don't have an alternator but the job still needs to be done and the 12V battery still needs to be replenished, but in our case it's the traction battery that does it via a DC/DC converter. The same principle still applies though and you'll still need a good run to do it - short runs with lots of electrical loads will drain the 12V battery.

Herbie, would you say that regularly doing 4 to 5 mile journeys would be too short for the hybrid Battery to replenish the 12 volt Battery?

[DJ Les]

I've had the Battery on trickle charge any a friends house this afternoon for a few hours while still fitted to the car, seemed to increase the voltage a little to 11.7. I can't do that at my own house as I don't have a drive or useable garage. Is there any issues regarding disconnecting and removing the Battery from the car to charge it overnight in my house. I'm thinking is there anything that gets reset apart from the clock? How would it affect the hybrid system, if at all?

 

[Herbie]

2 minutes ago, JeffL said:

Herbie, would you say that regularly doing 4 to 5 mile journeys would be too short for the hybrid battery to replenish the 12 volt battery?

In a good Battery that's not very old, maybe not Jeff. However, a Battery that's over five or six years old and perhaps not at its best, then maybe the journey may not be enough, especially if it's as bad as Les' Battery above and measuring a voltage well below par.

[Herbie]

1 minute ago, DJ Les said:

Is there any issues regarding disconnecting and removing the battery from the car to charge it overnight in my house. I'm thinking is there anything that gets reset apart from the clock? How would it affect the hybrid system, if at all?

I don't think it'll affect the hybrid system but the radio presets, windows and sunroof will probably need reinitialising when you reconnect the Battery unless you have a second 12V source to clip onto the cables to keep the circuits live.

[DJ Les]

Thanks Herbs. Radio presets are not a problem. Is there a specific procedure to reinitialise the windows and sunroof. Is this in the manual?

 

[DJ Les]

Ooh, just had a thought. What about the central locking? 

 

[Herbie]

2 hours ago, DJ Les said:

Thanks Herbs. Radio presets are not a problem. Is there a specific procedure to reinitialise the windows and sunroof. Is this in the manual?

Yes there is, but because I haven't got a 400h I'm not quite sure what it is although I know it's been mentioned in this forum previously. I think it's something like going round each window and using its own switch you drop them fully down then fully up, after which they should work as normal. Probably best to either look in the owners manual or do a search of the forum though.

[DJ Les]

Latest info, ran around the country lanes last night in the vain hope of getting some charge into the Battery. Checked it this morning before starting it, 10.45 volts, still started fine. I have the full service history from new, so, checked through it all and there is no record of a Battery being fitted. As I thought it is the original Battery from 2007.

Visited Lexus, Newcastle today and have arranged to have a new Battery fitted tomorrow. Price? They said £84 + free fitting, can't get any better service than that. 😀

[DJ Les]

Job done 😀

The Lexus dealer tested the old Battery after they took it off and said it showed 9.8v just barely enough to wake the car up. 😳

[PCM]

Good news!

😀

[Delphius1]

Don't forget that sealed AGM and Gel batteries have low charge rates (to avoid gassing) and need regular long runs to recharge them, or the occasional recharge at low charge rates to bring them back to their best.

Lots of use of accessories and short journeys coupled with a miniscule charge rate can significantly reduce the amount of charge in a Battery over time until its on its knees so to speak.

Some sealed AGM and Gel batteries can take up to 7 days to fully recharge from fully discharged because the charge rate (by design) is so low.

I used to design and test power supplies that used such batteries and in automotive applications they have their limitations. Which is why car manufacturers in general have gone back to wet lead acid or are looking at lithium based batteries (but lithium batteries have their own set of issues).

[DJ Les]

New Battery, identical to the 12 year old one it replaced. The red cover on the positive terminal was not in place, so, that tells me that someone has had problems before. Also, the nuts on the terminals have spanner marks on them and can only assume the Battery has been taken off to charge it in the past.