Potential NH450H+ Purchase - Question 12V flat battery

[ak888]

Thinking of an NX450H+, test drive was great and we like what we saw. With further research I have stumbled upon some reported issues with a flat 12V Battery if the car is left for a few days without use. Has this been resolved? This can be a showstopper as we can go without using a car for a few days quite often.

[rayaans]

Depends what you define as few days. 

If you leave it for 2-3 weeks it'll probably go flat so I'd get a trickle charger. 

A week to 10 days will be fine. 

[Husky125]

Just don't leave doors or boot open for a long time when washing or cleaning, mine has now gone flat three times. Have a jump pack in glove box, but now try to put engine on if doors open for a time. About to contact Lexus to see if a higher capacity Battery can be fitted.

Under normal driving every few days car works fine.

[ak888]

Typically will be a week between driving - unless on hols - then 2-3 weeks typically but unfortunately that happens only once a year.

Sounds like airport parking is out of the question for 2 weeks then? Is there any remedy from Lexus for this?

 

[Glyn Jennings]

I know it was a problem in lockdown because Hybrid's were not being driven for weeks on end which was is what I was told by Lexus at the time. I doubt it is a problem now but withy any car if you don't drive it on a regular basis a trickle charger may need to used depending how often the car is used. 

[Saxacat]

I've left mine for a couple of weeks without any issue, also it often goes weeks with only short journeys and then left for a week or so without being used; so far, I've not had any probs.

I did buy a Noco after reading about the issue, but I've not needed it so far for the NX; it has come in handy for helping other people with flat batteries though 😊

[Andy B]

41 minutes ago, ak888 said:

Typically will be a week between driving - unless on hols - then 2-3 weeks typically but unfortunately that happens only once a year.

Sounds like airport parking is out of the question for 2 weeks then? Is there any remedy from Lexus for this?

"Typically a week between driving" should be OK if you use the car regularly before this period of inactivity so as to get/maintain sufficient charge in the Battery. For example, I use my NX350h on my commute 3 days a week which comprises of approximately 45 minute trips there and back (mostly A roads at 50 mph). With this usage I have no concerns leaving it idle for a week or 2 (and have done so with no issues). Any longer than that then I may have some slight worries and would have my jump start booster pack ready and waiting (although I have never had to use it yet).

Just my experience but hope it gives you some crumbs of comfort. Taking all things into consideration, the Gen 2 NX is a great car IMHO.

[RONNIE W HODGEKINSON]

2 hours ago, rayaans said:

Depends what you define as few days. 

If you leave it for 2-3 weeks it'll probably go flat so I'd get a trickle charger. 

A week to 10 days will be fine. 

Spot On !!!!

[Scotlex]

I have left mine for three and a half weeks and it was fine. Started with no problems.

I regularly leave it for over a week with no problems. (we have 2 cars)

[Alan Thompson]

I've only ever had a problem once - and that was on my Mitsubishi Outlander PHEV. I'm on my second 450h+ without issue.

I've left it for 2 weeks to go on holiday and had no issues. Because of the issue I had with the Mitsi I bought a jump start booster pack which is only the size of a large mobile phone but haven't used it. I do charge this up before I go away and always leave the car with about 50% charge in the traction Battery when parking it for an extended period.

[Herbie]

6 hours ago, ak888 said:

Thinking of an NX450H+, test drive was great and we like what we saw. With further research I have stumbled upon some reported issues with a flat 12V battery if the car is left for a few days without use. Has this been resolved? This can be a showstopper as we can go without using a car for a few days quite often.

What is the Ah rating of the 12V Battery? There's a rough calculation you can do that will give you the maximum length of time it can stand unused but there's just too many variables for it to be very accurate. At least it's scientific and governed by the laws of physics rather than just anecdotal evidence where someone will inevitably claim that they left it for 6 months and it fired up first time on their return

[Scotlex]

I would like to think that any new (ish) car is able to be left for 2 weeks without being driven.

Airport car parks are full of various cars. The majority must be fine after 2 weeks standing.

[Ken R]

Never had a problem with this during my time with a NX300H, NX450h+ and now the RX450h+. 

[RXtoNX]

Only time my 12v Battery discharged was my own fault for leaving the doors open, ignition off whilst fitting a dashcam. It should have been in “ready” mode.

Ours has been left at an airport for 19 days without any issues & tbh, if the 12v Battery going flat is a concern to you then forget any type/model of hybrid. My daughter has a Tucson and her 12v Battery went flat whilst unloading the car on a camping trip.
Same problem with all hybrids, leave the doors open with ignition off for more than 15mins anfpd you’re inviting trouble.

[The_Doctor]

I have twice had mine parked up for over 3 weeks at a time without problems.

[Tickedon]

I’ve had mine sat unused for three weeks, no issues at all on return.

Have also had it sat unused for 1-2 weeks at a time, again no issues.

It isn’t a worry I have with my NX 450h+ (my partner’s Toyota Yaris is however a whole other question). If you are worried, get a USB power bank that doubles as an emergency starter and keep it in the car.

[Herbie]

If someone can tell us the Ah rating on the label of the Battery we can do an approximate calculation.

I'll guess at 40Ah, which means that it can supply 40A for one hour, or 20A for two hours and so on. If we assume a brand new and fully charged Battery and also assume a quiescent current draw of, say, 70mA (0.07A) that gives us the following:

40Ah divided by 0.07A = 571.42 hours, which is 23.80 days or 3.4 weeks to go from fully charged to fully discharged. The Battery will not be able to start the car long before it becomes fully discharged, so that will reduce the useable time available.

There will be variations such as temperature, condition of Battery, ie, has it been fully depleted before and if so, how long did it stay that way etc., etc., but this gives you a ballpark figure based on science rather than anecdotal evidence.

Please feel free to amend the figures based on whatever the real Ah rating is.

[RONNIE W HODGEKINSON]

On 11/5/2024 at 10:17 AM, Saxacat said:

I've left mine for a couple of weeks without any issue, also it often goes weeks with only short journeys and then left for a week or so without being used; so far, I've not had any probs.

I did buy a Noco after reading about the issue, but I've not needed it so far for the NX; it has come in handy for helping other people with flat batteries though 😊

Same Here >>Carry A Noco Jump start Unit And have DB2 to keep me updated on both 12v and hybrid Battery Charge..Perfect.. Never had a problem in nearly 3 Years