Won't pull away on battery

[NeilM]

Hi,

One day I noticed a change: I can no longer get the vehicle to pull away on Battery, despite it being fully charged, very gentle acceleration, and no hybrid errors messages. This is when I've driven the vehicle until it's fully warmed up to normal temperatures.

I also cannot get the vehicle to run on ev when slower than 30mph.

The display suggests town mpg of well less than 20 mpg. Ive never had that previously. 

I called the lexus dealer and the service dept just said it is likely to be cold weather.

Anyone in certain parts of the uk would know we've had unusually mild weather.

I thought there might be a software error and it needs a reset, bug the dealer ought to know.

 

Anyone have suggestions or ideas?

 

[NemesisUK]

Is it the same if you press the EV button immediately after starting?

[NeilM]

I have never tried that as usually, the engine starts almost instantly when cold. What will that prove? Ill have to wait until tomorrow morning to try that as the engine is currently warm.

[NemesisUK]

Not sure it'll prove anything but if the car goes into EV mode and moves it would suggest there is nothing fundamentally wrong with the hybrid system?

I've noted a number of times the ICE fires up but it's not driving the wheels, simply generating heat for the cabin. Motion is via the traction Battery. The  Energy display shows no power flow from ICE to the wheels but the engine is running...

[Carl911]

I sometimes find if the climate is on this weather the engine seems to kick in straight away. If the aircon, heater is turned off the engine often goes back to hybrid mode . That said, I have never dropped below 28.5 around town and most of the time I hover in the low 30's even in the current cold weather.

 

carl

[NeilM]

Thanks.

Even in eco mode i'm getting this problem occurring.

I'm going to try some experiments tomorrow by shutting everything off and seeing what happens.

The weather has turned slightly colder, and is now down to about 6c for tomorrow, so it may be not the best time to try this.

[NemesisUK]

Not Eco mode, EV mode. Do you have the separate button labelled EV? Forces the car to run only with the electric motor.

[NeilM]

Yup, ev mode. I have the button but rarely select it as the system seemed to work close to perfect. When I did select it, It certainly used to work fine when the Battery had plenty of charge.

 

I was referring previously to eco mode which should shut down various systems when at stop. Now, no matter what mode, the engine starts at the most gentle acceleration from, for example, traffic lights.

I wil experiment more in the morning on my next journey.

[GSLV6]

The RX is specifically marketed as a vehicle that will operate in all climatic conditions, from the arctic wilderness to the desert heat.  For Lexus service to simply write this problem off "as the cold weaver guv" is unprofessional to say the least.  If the RX hybrid system has an Achilles heal, they should come clean about it, but it does sound more like a charging issue.  It doesn't matter if it's in EV mode OR Eco mode because once charge runs below a certain amount, to prevent total Battery drainage, the system, even if in EV mode should switch to ICE automatically.  It sounds like a problem with the charging or storage system.  It should have naff all to do with the weather.  A medium or longish run, driving gently, to recharge the Battery will conform this.  Left overnight and without radio or seat heaters etc on, it ought to run on Battery in EV mode from the get-go.  If not, I'd be re-contacting the service department and not taking "No" for an answer.  Hot weather is as much a drain on batteries with many old Battery failures occurring in older vehicles with the additional loads presented by aircon running all the time.  

[ColinBarber]

Turn off the heating/aircon to see if that helps. The engine will run if the cabin needs to be heated.

[NeilM]

Thanks all,

In yesterday's long motorway journey I experimented withe various settings. I also checked EV mode and it was fine, operating up to about 25mph at which point the engine would kick in. That's exactly as I would expect.

I decided to make yesterday's an efficient journey, despite the traffic queues, and I managed around 35mpg, which i'm not unhappy about.
In traffic jams a super gentle touch on the accelerator would allow the engine to remain off.

I'm now wondering if it is specific circumstances that is causing the engine to kick in, including a combination of electrical demand, despite retaining gentle acceleration. I tried going through all the settings and switching through sport, eco, snow, and normal, and wonder if there might be a combination there that is not permitting a slow pull away on Battery.

I need to do more experiments, although the temperature has now dropped further which is likely to demand more from the Battery.

[NemesisUK]

On 26/12/2016 at 8:16 PM, NemesisUK said:

I've noted a number of times the ICE fires up but it's not driving the wheels, simply generating heat for the cabin. Motion is via the traction battery. The  Energy display shows no power flow from ICE to the wheels but the engine is running...

As I posted before, are you sure it's not using electric to pull away? The engine cutting in only to warm up and provide heat to the cabin?

[NeilM]

On 28/12/2016 at 6:24 PM, NemesisUK said:

As I posted before, are you sure it's not using electric to pull away? The engine cutting in only to warm up and provide heat to the cabin?

After extensive testing with various settings of interior and exterior power requirements minimised, on, and fully off, I can confirm 100% that it will not pull away on Battery power as it used to, as I originally said. Everything else seems to be working fine. It will run in EV mode when adequate power is available, and will cruise on Battery when little energy required. It's only that one operation that will not work.

I wonder if it's simply a software error and it needs resetting.

I'm having the vehicle serviced in the next six weeks and, as part of the warranty, i'll ask them to investigate this problem.