litpost

Issue I have is very strange. For me it just not logic. Maybe some of you have faced with similar problem.

So after 10 days of not using my NX300h (2018) today I tried to start a car. After I pushed Start button the message about Hybrid malfunction appaired. When I tried to push it with brakes there was no Ready status. After minute or two the system became just dead. It happened because 12V battery fully depleted.
I do not have battery charger so I just took out 12V battery from our second car and connected it to NX300h terminals under hood. The system went up and I managed to start the engine.

Now we are coming to issue. When I disconnected donor car battery the engine just stopped in a minute or so. I supposed to run fuel engine and charge board 12V battery. No chance! It stops because the car system see that hybrid battery is fully charged!
I just need to run car fuel engine non-stop until board 12V battery is charged.
I know I can just take out battery but to do that I need to lean through to back door and open it manually. And the to tale out the battery - That is annoying.
How to solve that in more intelligence way?

mcomer

Welcome to Club Lexus, how many Lexus owners are in Lithuania?

If you would connect the donor 12v battery with a pair of jumper cables to start
the hybrid and then disconnect them, the system would read the low voltage and
keep the gasoline engine running to charge it.

Because the 12v battery is really only used to stabilize the current used for the
radio/lights/defrosters and to open a relay so the 288v hybrid battery can actually
spin the gasoline engine the 12v battery is somewhat smaller than those used in
conventional IC cars. Leaving the car without running or using the Auxiliary function
to play the radio without running the IC engine does deplete sooner than a regular car.

litpost

Hi,
Lexus brand is rated at high level in Lithuania but due to its price there are not a lot cars on street.

That is my problem - gasoline engine does not run. It starts for few minutes and stops. That is not enough to charge 12V battery.

I am just curious - is it by design or is it something needed to repair?

mcomer

Are you actually driving the car or just letting it sit and idle? It would seem unlikely
the IC engine would stop and stay stopped while moving. Remember that the MG1
"Motor Generator" unit supplies current when deaccelerating which goes to charge
both the 288v Traction Battery and the 12v battery.

litpost

Hi,
I am not driving and just letting it sit idle. Something just drying 12V battery while it sit idle.
Normally when car is totally off all systems should stay off too.
Maybe in my case I have some low current shortage or something like that?
Is it possible ?

GS3Tek

iTrader: (8)

What happens when you try to drive the car?

Moving this to the hybrid section, hopefully more members with the hybrid can help you out.

litpost

I don't drive a lot. I have this car for few months and still have old one so still drive old car. That is why it stay idle in my garage.

Thanks for moving this to hybrid section.

Kar1n

don't forget you have sensors that monitor when car is sitting
your alarms, door locks if by touch, radar for closeness of objects for example

litpost

Could you specify it in more details please?

highender

I know this is an old thread.

But the OP should NOT just connect donor battery,,, start the engine... then disconnnect. Because the 12 volt battery is still depleted or possibly dead, because he said he doesnt drive it that much.
A hybrid car needs to be driven every few days. The long periods in which he does NOT drive it.... depletes not only the small 12 volt battery, but also the large hybrid battery. Batteries do NOT like to be depleted to zero charge, and then recharged. ALl of them will have life cycle decreased. The smaller battery will die slowly after 7 or 10 depletions and recharges. The hybrid battery can take more than that, but the lifespan and storage capacity of it will decrease.

All hybrids are built to be driven eevery few days. The small battery is used for some low voltage crucial systems, with hybrid battery following it to initiate start up. The internal combustion engine is the one that charges the hybrid and the small 12 volt battery. Some people mistakenly think the hybrid battery is the same as the 12 volt, or it can charge the smaller battery.

BillUK

I'm not sure I undertstand this. How does the internal combustion engine charge the 12v battery if there's no alternator?

During lockdown, the advice from Lexus, for a hardly used hybrid, was to put it in ready mode every few days, to keep the 12v battery topped up. During this time the ICE would cut in and out as required. This implied that the 12v battery was being charged by the traction/hybrid battery, and that the engine would cut in and out as and when the hybrid battery charge dropped, to keep that topped up.

In other words, it's perfectly normal for the engine to not run whilst left in ready mode, and the 12v batttery will still get topped up via the hybrid battery, with the engine only powering up to maintain the hybrid battery.

Is that not a correct understandiing of how it works?

highender

You are correct. I meant that engine does not charge the small battery, but the DC to DC converter uses larger hybrid battery to charge the small 12 volt battery. The ICE engine charges the hybrid battery......which charges the 12 volt......... 12 volt is needed for initial start of vehicle.


Key thing is .............. never leave the hybrid cars sitting at home or garage for long periods. I recall one expert say, that for people who leave cars for long periods, should NOT buy a hybrid, but a normal ICE car and keep charger on.

I do keep a trickle charger on mine, to prevent battery degradation.

litpost

I think I can leave hybrid in garage for a long time, just need to remove negative clamp from 12 V battery so battery keeps its charge unchanged.
By the way I never noticed any depletion of big battery after long time period in idle state (at least 10 days).
Please correct me if I am wrong.