Steven Lockey

Yeah as I said I'm not saying this DID happen, but its certainly possible it could happen, but would require the 12V battery to cut out at the exact period between the relays opening and the converter providing 12V to the computer to take over from the battery. Its probably pretty unlikely to actually happen in real life. The tau of a converter like this is probably sub 0.1s so its a pretty fine gap for the battery to die in. Might be higher if its designed to power the 800v circuit before the 12V circuit however but I've not dug that far into it. I'd completely agree its far more likely the battery just recovered enough after a short rest. I'm a programmer so I'm used to digging through documentation and trying to work out all possibilities, cos if I don't, well we call those bugs (or features lol) and no-one likes a bug.

You guys saying this can't happen 🙂 There must be a delay between the relays opening and current actually flowing through to the 12V circuit from the traction battery via the converter, simply because of physics, so if the 12V gives out during this time either due to additional charge been pulled or it just running out of charge, then you've got the circumstance I described above. Cos basically if the 12V circuit loses power for even a split second, the computer will disengage which should automatically close the relays again and the car turns fully off. The 300v circuit is still charged however and has a bit of power now stored in it and the only 'exit' for the power in this circuit is via the converter to the 12v battery. This will gradually leak out over approx 10 minutes according to Lexus. The component delay is called the 'tau' in electronics, I'm not sure what the tau is of the converter in the gs450h, but I can't see that the tau of the converter would of been a major consideration during the design process so is likely towards the high end. I know some extreme examples can have a tau measured in minutes. I'd expect it to be sub 1 second for a component like this but it could still be big enough to cause this to happen. How big that 'window' is would depend on the size of the tau of the converter which would affect how likely this was to have happened. I'm not saying this DID happen or that its at all likely to happen, but from the order in which the operations must happen to start up the car, its 100% possible that it could happen.

Sorry but that doesn't make sense. The laws of physics basically prevent this from been true 🙂 When I pressed the brake + power, the light came on and I hit the power button. Car light up, dashboard e.t.c. but very dim then everything went out. So clearly it had got to the stage of booting up the computer or the dash wouldn't have illuminated as that is controlled by the computer. Tried it several times and the exact same thing happened. It didn't get worse (aka dying sooner) or last any longer. Assuming the 12V was basically nearly fully discharged, you'd expect it to get worse with each attempt if there was no external power source involved. Its possible the 12V had just enough power to open the relays, causing the power to cut off to the computer after the relays had opened but before the 12V starts receiving charge, or some other process pushed the power-drain over the edge directly after opening the relays. That would leave a charge in the high power circuits which is directly connected to the converter and via that to the 12V battery according to the Lexus service wiring diagrams. Traction battery was basically full when I pulled up but was a bar lower when the car actually started according to the dash display. "There's really only two states - either there's enough power in the 12V battery to boot the computers and get the car into READY mode, or there isn't. And if there isn't, then there's just no way for the hybrid system to 'assist' the 12V battery." This statement can't be true as the car has to open the relays early in this process, so the traction battery is connected to the system before the car is in READY mode. Since the laws of causality prevent time-reversal, the traction battery MUST be connected to the system before the car is in ready mode, since other steps like starting the engine, bringing oil to pressure e.t.c. also need to happen before the car is in READY mode and rely on the traction battery been connected. Given capacitors are one of the biggest delays in electronics and boost converters use some big capacitors, this does leave a fair sized gap while the capacitors are charging that the 12V could cut out, causing the car to shut down but it hasn't got to READY but has charged the high voltage circuits (at least partially). The age of my car is likely an issue as I believe capacitors take longer to charge as they get older leaving a even longer time the car is relying on the 12V battery maintaining charge. Don't forget, stuff like this doesn't happen instantly. Just because the relays are open, doesn't mean power instantly starts flowing from the traction batteries to everywhere else. Capacitors take time to charge, transformers add a delay e.t.c. So even after the relays are open, the 12V is not instantly receiving charge from the traction battery. That leaves an interval in which the 12V can cut out but the high voltage circuits are now charged. The relays automatically close when the 12V battery cuts out but that doesn't instantly remove the charge from the high voltage circuit. Its like a gas canister you fill with high pressure gas, when you take the pump away and seal the top, the gas inside is still under-pressure till it can leak out and establish a equilibrium with the outside pressure. Same thing would happen in the high voltage system, where the power basically leaks out over up to ten minutes after the system is charged from the traction battery. Lexus specifically state not to touch any of the high voltage system till ten minutes after the car has been disabled as it can take that long for the high voltage system to fully discharge. One of the main places this power would 'leak' to is the 12V battery via the converter. If the battery was completely flat and couldn't open the relays, this wouldn't happen yeah, car would just stay dead. It may be this situation is a edge-case that only happens when the battery has a very specific amount of power, but unless the Lexus wiring diagrams are wrong, it definitely CAN happen, however unlikely it is. tl;dr; Power button pressed Computer boots Relays opened *Other processes to get car ready* 12V starts receiving charge from Traction battery Final processes to get car ready Car now in READY mode If the 12V cuts out in *Other processes to get car ready* stage, it would cause the car to cut out with the high-voltage system charged, which would then dissipate that charge into the 12V battery via the converter.

Yeah but what I was saying was the battery was so flat, it wouldn't even have activated the solenoid on a normal car. Literally wouldn't even run any internal lights or the security system e.t.c. Batteries that hit that level normally experience zero recovery without charging. You need a certain amount of residual charge remaining in the battery in order for there to be sufficient force internally in the battery to move the trapped electrons to the cathode, cos basically all you are doing when resting the battery is giving those trapped electrons time to escape where they are trapped. Without sufficient residual charge, they will never escape. This is one of the main causes of battery degradation, where the crystal build-ups get so thick that the electrons can't escape even at full charge. This is why hitting/shaking a battery can actually cause charge and battery life to be restored as the internal crystal formations can break down when you do this. As its an older battery (it the original) its likely mine has a lot of crystalline formations near the cathode and one of those degraded which released sufficient charge to start the car. The formation and break-down of these crystals inside the battery during charge/recharge cycles is one of the main reasons that old batteries not only lose capacity but become a lot more temperamental than new batteries. Just been doing some reading as well, seems that even if the car doesn't start due to low 12V battery, one of the first things the computer does is open the hybrid battery relays, which charges the high voltage system including the converter, which would then shut off as the 12V failed, but would leave the high voltage system charged and the only outlet for that power to be the 12V battery, so it'd basically give the 12V battery a little bump of power which that charge dissipates from the high voltage system (which can take up to 10 minutes according to the lexus dismantling manual). So its possible that attempting to start the car actually shunted more power into the 12V battery than it took out the battery and that was why it started up normally 10 minutes later. If your 12V battery is truly dead however, that isn't going to help 🙂

Yeah just normally if the battery is that flat, it isn't coming back without charging. Worked with reconditioning batteries a lot in a previous job so am quite familiar with them recovering slightly after a rest, just not to that degree. It can happen but its rarer, particularly with larger liquid core batteries. Also the battery would still go flat if the trickle charge amount was less than the amount drawn.

Odd, seen this happen when there is a little left in the battery, but never to the point where the car wouldn't even go onto standby mode to perfectly normal and I'd already tried all the tricks to eek that last bit of charge out the 12V but that didn't seem to have any effect. Maybe my 12V is just really odd 🙂

But the 450h and I assume the 300h automatically trickle charge the 12v battery from the hybrid battery anyway while the car is turned off. I've tested this a few times (accidently) by leaving the car in standby mode which solely uses the 12v battery, so long as you catch it before the 12v is too flat be trickle charged, so long as there is power in the traction battery, it will gradually recharge the 12v battery enough to start the car and switch to using the traction battery. 100% sure there is some charging of the 12V going on because it was basically dead once when I get back from a walk in the forest, (I left the lights on DOH), would lock/unlock but that was about it, no lights on dash e.t.c. Turned it completly off and left it for 10 mins (while I was looking up my rescue service on my phone), was about to call for help and thought sod it, and hit the power button one last time and the car started perfectly normally. Zero chance it would of had enough power to start the car without some form of charging, just sitting for 10 mins might allow it a tiny bit more power but it just had far too little charge left in it for that. Don't try this unless you having a jump-start nearby cos if you drain the 12V too much then all the trickle charging in the world won't help, you need a proper charger to get that initial charge back into the battery when they are completely flat.

Was referring to the multiple octane levels rather than Ethanol free side of it.

That might be true for Esso but they aren't the only petrol station 🙂

Agree completely that MOST MODERN cars will have absolutely no problem with it. On some cheaper/older cars, the fuel management system is particularly primitive however and higher octane fuels can result in too much pressure been placed on the valves. Its more of a legacy thing now I think. As I said its more for them to cover their own arses than anything else. At worst case it would result in the engine giving out a little sooner than it would normally.

Nah, generally the stations only have a limited number of fuel tanks so stock as many varieties of fuel as they have tanks (or less). I've seen a couple of stations stock 95, 97, 99 and 2 variants of diesel. Depends a lot on the area which one is more common, if the area has a lot of performance cars, '99 tends to be more common, but for example around Bournemouth, hard to find '99.

Nope, e10 has slightly less power available per litre than E5. You'll get around 97-98% of the fuel efficiency compared with E5 so slightly less. For it's eco-credentials, its now 10% bio-fuel instead of 5%, and as bio-fuel is carbon neutral (or better) this reduces the carbon footprint of the fuel considerably. E5 99 is performance fuel. I believe they put the * there because you shouldn't put it in cars that aren't designed for performance as it can cause excessive wear on the valves. Most cars it won't cause any issues but on a dinky little 1 litre they just aren't designed to handle performance fuels. Its more to cover their own arses than anything else 🙂

Nope, that is literally impossible. E10 has slightly less energy per litre than E5, like 99.4% of something like that so at best it'll slightly increase your fuel consumption. At the same time however it does burn cleaner and the greater % of biofuel in it means it's carbon footprint is about 10% less than E5.

Nope, it feathers the acceleration on the TCS as well so that might be related if the TCS is thinking its not safe to put the power down. Is the TCS lighting up at all?

Had the same thing and it was due to a brake imbalance across the pads, needed one of the callipers replaced as it was leaking slightly.

The higher-octane when it's not too excessive in price is always a preference on cars like this. Fairly sure all the GS series is perfectly compatible with E10 fuel however but not actually tried it with mine. With the recent price hike, the high octane has been like 2-4p a litre more expensive than the normal..... and with the slight improvement in MPG, it doesn't really cost much more anyway. If there's more than a 5p or so difference, I normally get the normal 95 Octane fuel. The EMS will automatically compensate for any difference both and as a driver you shouldn't really notice any difference unless you are really pushing the car REALLY hard.

My car lets me know in no uncertain manner when the battery in the fob is getting low lol. Does sound like another issue with the fob. I'd suggest cleaning the contacts and make sure they are holding the battery firmly in place. If they bend outward slightly the battery may be losing contract and the fob is failing even through the battery itself is fine. Replaced my fob batteries 3 years ago with 50p ones and still going strong.

I just found it on the marketing fluff 🙂

Cos if you ever want to drive properly, you need it off lol 😉 Part of the trick to driving a rear-wheel drive on the track involves slipping the back end out sometimes and the traction control doesn't let you do that. The LSD is mechanical I believe, you'd need separate motors for each wheel to do it electronically.

Try without the traction control on 🙂 I've found it depends on the road, if the road is really smooth with good traction, it'll put the power down hard much soon than 2 seconds in sports mode. I only drive in sports mode cos the normal mode feathers the accelerator and I do that automatically so I end up double feathering the acceleration and accelerating far slower than I wanted. Can also adjust these values in techstream I believe but not had the guts to play with the settings that much myself 🙂

That is well overpriced for a car with issues. The error could be anything, I'd not even consider it without ALL the above issues been fixed including the VSC light. More than a few GS available without these faults for cheaper: https://www.autotrader.co.uk/car-details/202109067068548 https://www.autotrader.co.uk/car-details/202107155077247?price-from=500&radius=1500&onesearchad=New&onesearchad=Nearly New&onesearchad=Used&postcode=ng15ga&model=GS 450H&advertising-location=at_cars&make=LEXUS&year-to=2021&sort=price-asc&include-delivery-option=on&page=1 for example. However do remember on the older GSes, check to see if these parts have been replaced: Exhaust Shocks Traction Battery (for H models) as at some point they are very likely to go on older GSes. The exhaust is about £800 to replace when it goes (or 2.2k from lexus) and the shocks are about £800 EACH from lexus or about £400 each for a non-standard non-adjustable version. The 300 uses the cheaper shocks anyway and I think the 300's shocks less likely to go as soon as its a bit lighter car. You can get a non-standard replacement hybrid battery from Hybrid battery solutions for about £2k. So if you do get an older GS, make sure you have the spare change to address these issues as they arise.

I'm guessing it doesn't work with the buttons on the steering wheel however?

On subject of reliability just saw this Lexus vs BMW Reliability - Why Lexus' last 300 00…: https://youtu.be/L-N16WyYxGE

Cos the phone can't do everything at the same time? Might want to do spotify e.t.c. on the phone or just let the kids game on it or whatever. Also the phone screen isn't as big as the main display so easier to read and you can see further ahead. Now if they integrated google maps into the main screen I'd love that 😉

If its treated well and serviced properly, I'd say more like 200,000+ Mine is on 188K and only issues raised on last MOT were the shocks which were the original ones and had just gone. Ha took me ages to work out how to do that. Was driving me mad particularly when it kept trying to send me down routes I know are bad 🙂 I generally go out for a drive at least once a week even if I don't need to 🙂