Herbie

Agreed - but not impossible. We've all passed the driving test, or at least I hope we have

Did the Green Flag guy tell you what the OBD error code was? If I remember correctly there are two 12V control relays that prevent current from flowing from the high voltage battery if certain conditions aren't met, but I can't remember what they are, so the OBD code will help me to look it up.

But the DC/DC converter in the hybrid will have an upper limit to the current it can supply, so if all those things are on then there's obviously less available to recharge the 12V battery, just as in the case of the alternator at idle. This is the reason why a hybrid car must never be used to jump start a conventional car, because the DC/DC converter can't supply as much current as an alternator can.

That's true but it can also be said for any car, hybrid or not. In a conventional car the alternator meets the 12V demands, in a hybrid the traction battery meets the demands - but it still happens. Any battery, of any capacity, in any car, will eventually go flat if not used regularly or trickle charged; it's just a matter of time.

Have you been using it for short runs and leaving it parked up for days between them or have you used it regularly and/or for decent runs? The battery takes much more of a hammering during the winter months when it goes dark early and the heater, the headlights and heated rear screen are used more, so unless it gets a good blast on a regular basis the battery will go flat sooner than is otherwise normal. If this is your scenario it may be best to leave the battery on a trickle charger when not in use. It would be a good idea to fully charge the battery and then go to a car accessory shop and ask them to check the battery for you. They should have a battery tester that simulates a load, rather than just checking the battery 'standing' voltage with a multimeter. If you've been using the car regularly and/or the battery is load tested and found to be good, then it's possible that you may have a fault that's causing a parasitic drain on the battery. This video may help find the problem if this is the case:

It's really all very messy and nothing is guaranteed to be as good as they look. I spent about £200 on a Carlinkit from Aliexpress but I just couldn't get it to work. I then decided to get a Grom Vline 2 which, as it turns out, was faulty so I'm waiting for a new replacement to be sent out, but I do have to say that I'm more confident about getting the Vline working than I was with the Carlinkit. Other options are to use Waze, Google Maps or Sygic on your phone, or to get a stand-alone sat nav such as a TomTom.

Well, yes, but I thought that went without saying.

If you're not happy with what Lexus are doing you could always take it to some other place. Being as you kerbed it, it can't be a warranty claim so any place that's good and does tracking will be able to do it.

Just a word of warning about that chart. I've posted it myself many times because there's no doubt that it's very useful but be aware that it only shows battery 'standing' voltage, i.e., off load. If you put a load on it by, say, switching on the headlights, the heated seats, heated rear screen etc., the voltage may drop like a stone if the battery is faulty. The biggest problem is that a lot of these things will only come on with the ignition. This is OK for the OP because he has a conventional car but for us hybrid owners we'd have to have the car in READY mode and because that activates the charging circuits it would show about 14.5V. It's best to go to a car accessory shop (and I hate to say this but even Halfords) to ask them to check the battery for you. They have special testers that simulate a load so you get a truer and more accurate reading.

I don't wish to personally attack anyone or cause offence to anyone but come on, the RX isn't THAT big! Do delivery vans, bin wagons, BT vans, milk tankers and suchlike manage on these narrow lanes? If the answer to that is yes then it's not the RX at fault is it? And yes, I do live in a town but having holidayed (is that even a word?) in Devon and Cornwall many times I'm no stranger to those narrow lanes by any means.

Because the factory satnav/infotainment system has long been the Achilles Heel of Lexus and is abysmal., which is why a lot of people, myself included, look for alternatives. As a quick and dirty fix to get your wife home she could use Waze or Google Maps on her phone. I suspect that she won't have a phone cradle or holder of any sort but the phone could just sit in the cup holder as the voice instructions are excellent and either of those maps will give advanced warning of problems and workarounds for them. Longer term, either a phone in a holder or a dedicated satnav like a TomTom, or a way of getting Android Auto/Apple Carplay in the system because they would then control screen brightness. It may sound daft to use a third-party solution but as I said earlier, the factory nav is terrible, being slow, clunky, counter-intuitive and just does not work well. I can be two miles down the road and into my journey using Waze, Google Maps or Sygic, before I've even finished inputting my destination in the Lexus system.

Unlikely to be a fuse because if it was then the lights wouldn't work when the passenger door was opened. There's usually only two or three locations for fuse boxes - engine bay, passenger's and/or driver's footwell - and the fuse box lids usually have fuse number and circuit description on them. Most likely culprit in this case is the door switch, which is often a plunger that moves in and out as the door is opened/closed. You may find that the plunger has seized.

I've only had one email from them about that but I think it was only about 3 months ago that I renewed - so I'm peed off for a different reason

And posting that (without explanation or context) achieves what exactly Russell? I'm assuming you're attempting to back up your theory that there's a problem with the RX400h 12V battery? I suppose there are two possibilities: There is a real, actual, parasitic drain on the system. Have you investigated this? The only thing wrong is actually a design problem in that Toyota/Lexus specified a low capacity 12V battery Given that the RX400h ceased production in about 2008 (latest I've seen registered is 2009 with the RX450h taking over from then), good luck with getting Toyota/Lexus to do anything about it now. The only options now are to either put up with it and plan for when it goes flat or you change the car because it doesn't fit your usage pattern. I suppose a third option would be to try to find a higher capacity battery that physically fits in the battery tray. So you did 70 miles on Monday 22nd then didn't use the car again until Sunday 28th. How many miles did you do in the previous week, i.e., 15th to 22nd? All batteries in all cars will go flat if not used, it's simply a matter of how long that takes.

The factory navigation has always been the Achilles Heel of Lexus. I believe it's getting better now but it'll be a long time before I can afford a 2021 car so the most useful apps are the map/nav ones such as Waze, Sygic, What 3 Words and others that are all much better than the Lexus offering, especially as most of them are free, updates are both free and frequent and they are all easier to use. I believe (maybe wrongly) that both Android Auto and Apple Carplay will not allow you to load apps such as Netflix and live TV for the legal reasons you already know about. However, third-party devices such as Carlinkit, Grom Vline 2 and Lexion do allow it and must just rely on the common sense of the driver not to use it in motion.

I would imagine that the red bar with white lines is the icon for "STOP NOW!!" and I would hazard a guess that the sensors at the front either need cleaning or maybe even replacing, because they seem to think you're almost up against an object. Once you've got those sorted then you'll be able to activate Park Assist and just leave it on to come into play automatically when needed.

Excellent job and write-up Ollie, I eagerly await the next instalment

It's not so much a 'small battery' issue as a usage issue. Whether it's a big 100Ah or a small 40Ah, the capacity should have no bearing on the longevity of the battery, which should run to well over two years these days. The problem is that people either don't use the car enough or only use it for short runs and, if that is indeed its usage pattern then a trickle charger should be used when it's parked up. I don't know what capacity battery the RX400h uses but let's say 45Ah and let's assume that it's brand new and fully charged. If we take the quiescent current as being 50mA (0.05A) like I said above: 45Ah means it can supply 45A for 1 hour, or 22.5A for 2 hours and so on. 45Ah / 0.05A = 900 hours or 37.5 days or 5 weeks 1 day from fully charged to fully discharged Remember though, this example assumes a brand new and fully charged battery, which obviously won't be the case in the real world a hybrid takes about 20A to reach READY mode so in reality the battery will not be able to start the car well before it becomes fully discharged, so we lose some time there for various reasons the car charging system is nowhere near as good as an external charger so a 'half-hour blast' won't do anything to top up the battery; it would need to be a couple of hours at least Hardly scientific and perhaps not even a good example, but I hope it gives some sort of indication that you can't really leave cars stood around doing nothing for extended periods of time, or only do short runs, without the risk of the battery letting go.

Is wireless really a good idea anyway? I would imagine the power demand would be quite high and constant, meaning that you could get to your destination with very low battery on your phone.

Don't worry, the trip won't take that long

I think maybe Monica is another 'one post wonder' who never comes back to let us know how things panned out.

The manual lock can get quite stiff due to lack of use. After all, who would choose to use it when we have the fobs and the alarm? I've read that some people have had to resort to using a pair of pliers to give extra 'oomph' so I think this is maybe what's happening here. You're not actually turning the key enough to operate the lock. You need to be brave and try harder. Of course, I take no responsibility if it all goes Pete Tong and I can't be held responsible for anything unless my suggestion works and then I'll take the credit

I think I've answered that in an edit that I must have been doing while you were reading the post Geoff Yes, you can do it that way if you prefer mate

I don't think it's an easy thing to do Geoff. According to our Gtech battery it's 22V, so unless you have an 'auto-ranging' meter like the one in the photos below, you would set your meter to the DC voltage range that is higher than 22. One of my meters has a 20V range and the next one up is the 200V range, so that's what I'd need to use on that meter. That's the easy bit. The problem is that you can measure the voltage but I don't think that information is of much use, because you can't test the circuitry that's also in the battery pack, so you won't know if it's the batteries themselves or the electronics that are at fault. It's possible that the electronics are there purely to drive and control the charging LEDs but I don't know; it may also have some current-sensing stuff in there to control rate of charge and to stop it from overcharging. Looking at the battery terminals on the outside of the case, at each side of them is a T9 Torx screw. Undo those and you can open the case. At the opposite end to the charger socket is a row of solder 'blobs', one slightly out on its own at the left and then 5 others next to each other like so: x xxxxx The one to the left on its own is the positive so put your red probe on there. Use the black probe to touch each of the other points in turn, starting at the left. I'm not sure how this will look when published but it should hopefully work: x x x x x x +ve 0V 22V 18.7V 18.7V 0V EDITED TO ADD - you can test the charger by plugging it into the battery and putting your test probes on the back of that connector. The charger output is 27V.

Have you let it discharge and then sit there for a while, i.e., parked up for days on end and then only short runs? They don't like those scenarios and that would certainly contribute towards a battery dying before its time. If you feel that it really is down to a fault causing a parasitic drain, the video below shows the best way to go about tackling this problem. Just remember that the car will always draw some current to keep the alarm alive, the radio stations in memory, to keep the clock at the right time and so on. This is called the quiescent current and around 50 milliamps (50mA or 0.05A) is considered to be normal.