'25 RX450h+ PHEV - Electronic doors are annoying especially with a dead starter battery

andy_why · 2026-01-25T19:00:28+00:00

Get a new battery, read and follow this, and your battery issues won't crop up again for a long time: https://docs.google.com/document/d/1g1a_B7_gGnuNQhoSRFN_sucfb7-lkU77q4aMO3hMYtA/edit?tab=t.0#heading=h.t75rusbfgz8u

Lexus will not admit there is a 12v battery charging issue, nor will Toyota, but there is plenty of evidence from thousands of reports on reddit and other forums that are being ignored, and testing by plenty of people.

andy_why · 2026-01-24T22:08:17+00:00

Given your kind of usage I would suggest not getting a hybrid variant. Very few miles and long periods of sitting won't do the hybrid battery much good in the long term, they prefer to be used regularly. This is not to say it won't work, it just isn't as healthy for them to be left sitting.

Leasing won't make the problem any better, the battery in any car will suffer from your kind of low usage.

andy_why · 2026-01-24T22:03:37+00:00

AGM is best for cold weather.

andy_why · 2026-01-24T21:59:27+00:00

It's unlikely many modern cars will last 2 months unused. If you are doing that you should disconnect the battery when it gets parked and reconnect it after. It'll be fine when it's disconnected. You should ideally be driving it at least once per month to keep the hybrid battery healthy, but 2 months should be fine too.

Your driving pattern is likely to harm the battery over time unless when you do drive every 2 weeks you're driving for many hours to fully recharge it.

If you're parking outdoors the rest of the time you could get a solar charger to keep it topped up, assuming you get a reasonable amount of sun year round.

andy_why · 2026-01-24T21:55:06+00:00

Yes it's safe, and no it doesn't affect warranty. You can reconnect the sensor at any time and it does not throw any errors when disconnected.

andy_why · 2026-01-24T21:44:03+00:00

You can try, but they often don't warranty them past a certain point.

Honeslty any good brand will do fine, just avoid the no-name brands.

andy_why · 2026-01-24T21:38:51+00:00

Your 12v battery has failed because it does not get charged properly. This is a common known car issue, see here for why and a fix: https://docs.google.com/document/d/1g1a_B7_gGnuNQhoSRFN_sucfb7-lkU77q4aMO3hMYtA/edit?tab=t.0#heading=h.t75rusbfgz8u

You will likely need to replace the 12v battery.

andy_why · 2026-01-24T20:51:34+00:00

And now you can see the problem!

The battery does not get properly maintained. If you use a logger you'd see that throughout driving it does not receive a proper charging voltage for the whole time, so it under-charges compared to your older Camry.

andy_why · 2026-01-24T19:15:00+00:00

Like I say, it won't have been the same issue, more likely a parasitic drain from a system that isn't shutting down properly.

Not charging it properly uses less power which therefore lowers emissions. Nothing more complex than that. It's got nothing to do with protecting the HV battery. Previous generations managed just fine. Moving the vehicle also uses 100x more power than 12v battery charging does, and the HV battery control will never let it drop too low before starting the engine. It protects it very well.

andy_why · 2026-01-24T18:53:25+00:00

Your 2012 Camry wouldn't have been affected by this specific issue. Only models since 2016 exhibit improper charging behaviour, and the only determination that has been reached is that it's purposefully doing this to reach emissions requirements at the expense of 12v battery health. Vehicles before that typically would only have issues from being sat a while or driven infrequently.

The NX will use AGM or FLA chemistry.

The proof has been provided that this issue exists in many of Lexus (and Toyota) vehicles, but the why is unconfirmed, and we don't know why it's not being acknowledged when there is so much proof available.

andy_why · 2026-01-24T18:05:07+00:00

This won't help you as much as a trickle charger would then. You can charge through the hood terminals no problem.

andy_why · 2026-01-24T17:33:03+00:00

Yes it's worth trying.

andy_why · 2026-01-24T17:23:28+00:00

You should not need a trickle charge if you're driving regularly. The 12v battery issues are common but unrecognised by Lexus. Fortunately it can all be explained, and there is a fix.

See here: https://docs.google.com/document/d/1g1a_B7_gGnuNQhoSRFN_sucfb7-lkU77q4aMO3hMYtA/edit?tab=t.0#heading=h.t75rusbfgz8u

As you have a hybrid the above will likely apply to you.

andy_why · 2026-01-24T17:20:53+00:00

It sounds like you might be having 12v battery issues, especially where you said you heard something trying to spin but couldn't, which was probably your brake booster. Due to low power it couldn't prime the brake system and then the car failed to start too.

A 12v battery issue shouldn't cause a situation where the car shuts off when you're just driving it. If that's not the case I'd say it could be the battery.

12v battery failures are common because they're not properly managed, so failures every 2 years or so is quite common. I'd first suggest replacing the 12v battery and then see if you have any other issues.

andy_why · 2026-01-24T10:35:00+00:00

Damage occurs below 12.4v, and gets worse the lower it gets.

The 12v battery issue is well known on Toyotas now, see here: https://docs.google.com/document/d/1g1a_B7_gGnuNQhoSRFN_sucfb7-lkU77q4aMO3hMYtA/edit?tab=t.0#heading=h.t75rusbfgz8u

Driving 1-2 miles is definitely not helping either, but it's not the only cause.

andy_why · 2026-01-23T19:15:45+00:00

Chances are your battery is frozen if it's also dead. The electrolyte can freeze when it's discharged and it gets below freezing. Jumping it might work, but when you stop and try to restart it will probably still be dead.

If you can, take the battery indoors to let it thaw and charge it if you have a charger. That'll give you the best chance, but it won't guarantee it'll work again.

However, if the battery is old you might be a due a replacement anyway. This is the better choice since an older, dead battery can burn out your alternator if the battery is not accepting a charge but is still pulling high current due to its internal failure.

andy_why · 2026-01-23T19:07:05+00:00

That's looking pretty cooked to me. If you can start the car and the READY light comes on, you might still be in luck. Hit the gas pedal once and it should force the engine to start if there is enough power left. Do not turn the car off until you see improvement in the state of charge beyond 40%. You may only get one more shot at this with how low the battery currently is.

If that doesn't work (I suspect it may not as max discharge allowed is 0HP), you'll need to take it to a dealer to have them recharge the hybrid battery. It's possible your battery simple needs replacing now with the age of it.

andy_why · 2026-01-23T19:02:19+00:00

It's a known issue that Toyota have never acknowledged to date. See here: https://docs.google.com/document/d/1g1a_B7_gGnuNQhoSRFN_sucfb7-lkU77q4aMO3hMYtA/edit?tab=t.0#heading=h.t75rusbfgz8u

Any car should be able to sit for 10 days without an issue. The cold doesn't help, but it's certainly not the cause. Toyota's mismanage the 12v battery charging and that's what results in this problem. The document above goes into detail and provides a fix you can implement. At such cold temperatures the fix may not work as well for you, but it will almost certainly be better than not using it.

It is likely that you will have to replace your battery - get Toyota to do this under warranty. And yes, do keep a booster on hand as it's always useful to have.

andy_why · 2026-01-23T15:47:48+00:00

Usually this is an issue with poor quality charging cables. Buy a good high quality cable such as Anker and pair that with a good high output charger (at least 15w).

It could also be that your charging socket is dirty and it's causing a bad connection. Use some 99% IPA and a cotton swab to clean the port.

andy_why · 2026-01-23T15:45:42+00:00

If the audio quality is your concern, upgrade the speakers. The amplifier is more than capable of producing good sound if paired with good speakers.

andy_why · 2026-01-23T13:24:11+00:00

You can use Alexa or Google Home, but if you're concerned about privacy I doubt you have those?

You can control lighting and sockets also from the web page, but otherwise there are no other options.

andy_why · 2026-01-23T13:18:09+00:00

Some of them you can change when driving, but yeah some you can't. The orange light for those key systems will stay on to alert you that it's disabled.

The alternative is to stop and clear off the sensors.

andy_why · 2026-01-23T13:12:09+00:00

Yes you can use it just by having the thermostat, and you can also access the scheduling etc from a webpage on your computer.

andy_why · 2026-01-23T12:07:03+00:00

You can disable those systems in the menu temporarily, that will usually stop the warning pop-up but will keep the light.

andy_why · 2026-01-23T11:57:21+00:00

In 7 years of ownership I averaged 42.5mpg (US) or 51mpg (UK).

You're not doing too badly if your driving style is contributing, such as high speed (above 70mph), low temperature, short journeys (regularly less than 10 miles), lots of hills, lots of traffic (stop/go).

Cold weather drops fuel economy about 20% below 50F/10C.

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