12v battery failurep

[NemesisUK]

This Lexus-tech.eu doc is for my RC300h but it will be very similar for other hybrids. It's worth a read through..

 

CHARGING SYSTEM ON-VEHICLE INSPECTION.pdf

[WillOz]

Many thanks Nemesis. Will check it out.

[wharfhouse]

1 hour ago, WillOz said:

Thanks Wharfhouse. I am new to hybrids so all info is good many thanks for your time. However when I quizzed the sales people and after sales rep he did say they had an increasing number of this 12V battery problem. It all does seem to depend on what level of kit you have using the electronics. I can't see why anything would be running apart from the key and security system. Oddly I bought this ex demo nine months ago and it was the After Sales reps car! However all they could suggest was charging and testing the battery. It has just been serviced so again I'm surprised it wasn't picked up, the computers log everything, well not really but...

The After Sales Rep did point out that all the cars in the show room were on trickle charge.

Anyone any idea what the wattage drawdown should be or indeed what should be drawing this power?

Cheers and thanks for all the ideas.

Well to be honest I think the dealer is talking BS. Once the car is locked there is only the alarm/immobiliser and the smart entry system polling (which IIRC also shuts down to some sort of low power mode after a period of time - I think a few days). Regardless of the equipment levels /trim that's it. I don't know what that draws but if the car was run for a eg a couple of hours before being left and the Battery is in decent condition you would certainly be able to leave it for for 5+ day (as Nemesis said he has left his for 3 weeks and I've left mine over 2 weeks) and start it ok. 

[Herbie]

1 hour ago, WillOz said:

Anyone any idea what the wattage drawdown should be or indeed what should be drawing this power?

Forget the power for the moment because quiescent current is usually spoken of in milliamps (mA) rather than Watts.

When the car has fully gone to sleep then things like the alarm, entry/exit system, radio presets, clock and so on will still be drawing power to keep them alive and/or in memory. In theory there should be an official figure available from the manufacturers specifications to show what this quiescent current draw should be, or what's considered to be normal for a given model/variant. I've never seen such a figure but I believe that around 50 to 60mA is considered the norm in the auto-electrical industry and anything much above this indicates a fault condition.

The Battery on my 4RX has a rating of 60Ah (I think - too cold and wet to go outside to confirm), which means that it should be able to provide 60A for 1 hour, 30A for 2 hours and so on.

If we assume a brand new and fully charged Battery with a quiescent current draw of 0.05A, then 60Ah/0.05A = 1,200 hours or 50 days or 7.14 weeks to go from fully charged to fully discharged if the car isn't used and is left standing.

In reality, the Battery is unlikely to be brand new and fully charged; plus the Battery will not have enough power in it to start the car long before it becomes fully discharged.

Going back to my apprenticeship days, if I remember correctly P = V x I, so if a lead-acid Battery is considered 100% charged at 12.7V, that's 12.7 x 0.05 = 0.635W.

If you're seeing 4W then I = P/V = 4/12.7 = 0.314A instead of something around 0.05A (don't forget though that this calculation is assuming your Battery voltage to be 12.7V).

If you think you may have a problem then the video below is by far the best way of finding out what it is:

 

 

[wharfhouse]

3 hours ago, WillOz said:

2019 300h has gone through two 12V batteries from Lexus and doesn't last more than 5 days.

It's also still under Lexus mfr 3 year warranty at the moment but may not be soon (depending on when registered in 2019) so would make sense to be applying some serious pressure on Lexus to understand what is going on whilst still under warranty if the car is being used in a "normal" way. 

[WillOz]

Thanks Herbie and Wharfhouse. I shall do the tests as per video and apply pressure to Lexus. Many thanks and have a good and safe new year.

[mikejt]

This may be of interest to you. My experience of failed 12v Battery. BTW they are only 45 Watt hours. 

 

[08ISF]

What seems to me to be faintly ridiculous is that these cars come up with warnings about all sorts of things (including a periodic warning on mine that "LKA not available" which it wouldn't be because  I've turned it off) but they can't monitor the 12v Battery state and give us a warning when it  isn't what it should be. That to me is the real design fault, as is the lack of facility to jump start from the  traftion Battery.

[Herbie]

2 hours ago, 08ISF said:

as is the lack of facility to jump start from the  traftion battery.

I'm not sure if it's for safety reasons or to protect the electronics but this can't be done because there are two 12V relays that act as a low-voltage interlock. If there isn't enough 12V power to operate this then the hybrid system cannot start and so can't charge the 12V Battery.

Quote

these cars come up with warnings about all sorts of things [...] but they can't monitor the 12v battery state and give us a warning when it  isn't what it should be. That to me is the real design fault, 

I do agree with that - it should be trivial for them to do this.

[PDM]

37 minutes ago, Herbie said:

I'm not sure if it's for safety reasons or to protect the electronics but this can't be done because there are two 12V relays that act as a low-voltage interlock. If there isn't enough 12V power to operate this then the hybrid system cannot start and so can't charge the 12V battery.

I do agree with that - it should be trivial for them to do this.

My 21RX (golly that's now last year!) has a 12V Battery status bar on the Lexus link app, so I guess for cars built after late 2019 (when WiFi hotspots started to be included) we now have this feature.  Although I'm not sure if the Battery status updates over time when the vehicle is parked up... I've not had the Battery go low yet to test it.

Paul

[Herbie]

I fitted a GPS tracker to my car. Nothing fancy, no central monitoring or police tracking etc., but it was just under £45 and costs about £60/year for the data SIM.

It gives live tracking data so if it gets stolen I can call the police and tell them exactly where it is, how fast it's going and so on. In fact, I'm blown away by just how much information it gives, not least of which is a page dedicated to showing info from six different sensors, amongst which is the vehicle 12V Battery status, as shown in the screengrab below.

[Thackeray]

That looks a useful and good value device.

It's also interesting to see that it looks as if you can start the car with the Battery at 11.65v (I'm assuming you haven't had to jump start it). I don't suppose that would be enough power on a conventional car and increasingly suggests the Battery is designed to operate in a lower voltage range.

As you've pointed out before, the 14.5v volts is the normal voltage when the car is in the Ready mode although the average figure probably doesn't tell you very much if it combines periods when the car is running and not running.

All of that, of course, doesn't detract from all the criticisms above. In particular, the car can produce a warning when the Battery in your keyfob is getting low - how come that doesn't happen for the main 12v Battery?

 

[Steve_S]

So I had to jump start my car last weekend after it had been sitting a few days. I charged it backed up then I drove it again for an hour on Wednesday. This afternoon (Saturday) I checked the voltage across the 12V Battery (before starting it) and it read 10V. When I tried to start it it flashed the usual hybrid shift to p warning for a second before it did actually manage to start up on its own accord this time. But anyway, a new Battery is required I guess.

[ColinBarber]

4 minutes ago, Steve_S said:

So I had to jump start my car last weekend after it had been sitting a few days. I charged it backed up then I drove it again for an hour on Wednesday. This afternoon (Saturday) I checked the voltage across the 12V battery (before starting it) and it read 10V. When I tried to start it it flashed the usual hybrid shift to p warning for a second before it did actually manage to start up on its own accord this time. But anyway, a new battery is required I guess.

Yeah, for it to lose that much charge in a few days then the Battery has failed. I'd expect 12.2 v worst case after 3 days, and ideally 12.4 - 12.6 v.

[Steve_S]

Thanks Colin. Cheers.

[WillOz]

Further to my 12V Battery problems. I got a new smart charger and that seems to have cured the problem. I think the Battery had got into a very low state and needed a good charge up. It is a new Battery but as it says in the manual a bit of mileage to keep it okay. Worries me about leaving at an airport so the small lithium Battery is always an easy fix and good if you can't plug in a charger at home too. I've actually hard wired it into the 12V Battery so I just need to plug in the special jump lead plug into the backup lithium if/when needed. I don't think it is acceptable these days to run the engine, use petrol, cause pollution etc. for no other purpose than to trickle charge the Battery.

 

Many thanks to the  forum for all your help. It is good to know I'm not alone.

 

WillO

[WillOz]

Further to Battery drain issues. As mentioned before, on a frosty morning you can see the camera is ice free. QED it is drawing power. Why do that overnight?

Also the Watt meter test I did, before using a smart charger looked like this.

The clue I think is 6.42 Volts. The smart charger now show anything from 12.6 to 14V

 

 

Close up: 

[Bluemarlin]

If the camera is hardwired and set to parking mode then it will draw power, as it's set to record any interference with the car while parked. Further, some dash cams will even deliberately give off heat in parking mode to ensure the screen is defrosted so that it can record properly.

[WillOz]

Thank you Bluemarlin. By "Parking mode" I assume you mean it is parked, switched off as one would with a more conventional car. I didn't know it did anything other than feed the speed signs into the display and control the Auto lighting mode. Interesting, many thanks. I haven't had a flat Battery since a "smart" recharge so I hope that might help others. 

[Herbie]

Think you're getting slightly confused there William.

The car camera does the speed signs, auto-lighting and so on but it doesn't act as a dashcam, which is what 'Parking Mode' eludes to.

[Johnhodgo]

On 12/27/2021 at 9:06 AM, steve2006 said:

Initially confused by the acronym “ICE” which I had always understood to mean “In Car Entertainment” and given that it was also mentioned that the problem on several occasions occurred after the radio had been left on. I did however deduce that the same now relates to Internal Combustion Engine.

I think aviation is the ultimate environment for acronyms, anyone know the following without getting google involved ...PAPI, ATIS, ECAM and TOGA ( the last example not being a Roman garment) 😀

Answers on post 12,005.

 

Precision approach path indicator ( lights),automatic terminal information systems, electronic centralised aircraft monitor, take off/go around, i think.

[WillOz]

Yes Herbie confused as I don't have a dashcam only the Lexus speed reader etc. That was the camera the pictures related to. I think Bluemarlin misinterpreted what I meant. Lack of clarity on my part! So still don't know why it is drawing power overnight.

[Bluemarlin]

Indeed I did misinterpret, I wrongly assumed it was a dashcam.

[Herbie]

2 hours ago, WillOz said:

Yes Herbie confused as I don't have a dashcam only the Lexus speed reader etc. That was the camera the pictures related to. I think Bluemarlin misinterpreted what I meant. Lack of clarity on my part! So still don't know why it is drawing power overnight.

Looking at that picture of the power meter it seems that you're measuring total current draw from the Battery, or have I got that wrong?

What I'm getting at is, are you sure it's the camera that's drawing the power and not something else? Did you do the tests as shown in the video?

[WillOz]

Yes it was total power draw. All I could tell was that something was drawing power and I was surprised that the camera seemed to. It is one thing for the door security system to be active but the camera? Still as long as we know...