Parasitic drain checking.

[Poundy]

Looking for a little advice on  the procedure for shutting the Wife's CT200h completely down without the alarm going off with the tailgate open.

I think we have a Battery drain happening when the car is stood. I have an Amp clamp in my tools somewhere so will not need to disconnect the Battery lead.

I'm just concerned if I flip the tailgate lock so it appears closed then lock the car with the fob and start working inside I may set off the motion sensor.

Cheers 

 

[Herbie]

This really IS the best way to check for a parasitic drain, including the procedure to put the car to sleep:

 

 

[Poundy]

Hi Herbie,

My concern is while he has all the doors open but latched, and shut down on the fob. What is preventing the alarm going off while he is rummaging around in the interior fuse box and waking the system up again?

My initial step will be to check the neg Battery cable for estimated drain before progressing to fuse checking if required. I presume I will just need to flip the 1 door and bonnet latch to cover the access to the 2 fuse boxes then. 

[Herbie]

1 hour ago, Poundy said:

What is preventing the alarm going off while he is rummaging around in the interior fuse box and waking the system up again?

1. In my 2018 RX there's a push switch up in the overhead panel that turns off the internal alarm sensors (shown below) and I'm sure your CT should have the equivalent somewhere.

2. DON'T pull any fuses and/or relays because if you do, you will wake something up and that's the last thing you want as it will lead to misleading results. I realise that you're aware of this but I see no harm in reiterating it for others in the future

[Brian R]

What a useful YT video! Funny enough, I have just installed a new 12 volt Battery into mine in the belief the original was/is on its way out. However, looking at the latest stats from a Battery monitor I have fitted, I'm inclined to think I too have some parasitic draw and fortunately I believe I know what could be the culprit. Time to put the "Humble Mechanics" advice to the test.

Many thanks Herbie for the video, and I think it will now be easy to pinpoint the draw.

[Poundy]

You are correct Herbie, after checking inside the car there is indeed a motion sensor off switch in the interior light switch.

On reflection, I think it may have been an ongoing problem since we purchased the car in 2018. The car struggled to get above 12v then, so soon after I fitted a new lexus Battery. Even so there was no real noticeable Battery performance with the new one fitted, always dropped down rapidly if stood for a week or so. I guess I just got into the habit of popping the charger on being as it only does around 3k mls a year.

I did a Battery condition test the morning after charging and it came back as Health 85%, CCA have dropped from 345 to 325, the charging circuit is good and the numbers are pretty impressive considering the Battery is now 4yrs and 2mths old. The only negative, it said it was still in need of charging. 

It's due for service in March and still under the Lexus paid warranty, so if I can troubleshoot it a little and determine there is a drain I can push them to sort it. Of course it could still be just a dying Battery, we will see.

Thanks for the input Herbie.

[Poundy]

3 hours ago, Brian R said:

What a useful YT video! Funny enough, I have just installed a new 12 volt battery into mine in the belief the original was/is on its way out. However, looking at the latest stats from a battery monitor I have fitted, I'm inclined to think I too have some parasitic draw and fortunately I believe I know what could be the culprit. Time to put the "Humble Mechanics" advice to the test.

Many thanks Herbie for the video, and I think it will now be easy to pinpoint the draw.

Hi Brian keep us posted if you find a draw and what was causing it

I downloaded a PDF of the relevant fuse boxes and descriptions here if any one needs them

 

Lexus fuse box.pdf

[Brian R]

Will do Norman just as soon as I get a spare moment. FYI I think it is my dash camera that is the culprit given it goes into "parking mode" when the engine is stopped. Looking at the very limited internal Battery reserve and some of the videos it records, then at times it simply has to draw on the cars Battery. The most interesting vid it recorded was that of a crow attacking my cars wiper blades! There are three would be culprits that seem to revel in causing damage. Time and again there is evidence of their hooliganism with all sorts of debris scattered over our drive.

Pictured is one of the hooligans.

[Las Palmas]

46 minutes ago, Brian R said:

Will do Norman just as soon as I get a spare moment. FYI I think it is my dash camera that is the culprit given it goes into "parking mode" when the engine is stopped. Looking at the very limited internal battery reserve and some of the videos it records, then at times it simply has to draw on the cars battery. The most interesting vid it recorded was that of a crow attacking my cars wiper blades! There are three would be culprits that seem to revel in causing damage. Time and again there is evidence of their hooliganism with all sorts of debris scattered over our drive.

I believe that an extra Battery for the camera could solve the problem.

Charge it from the 12V Battery in the car, protect the car’s 12V Battery so it only charges your camara-battery when engine is running.

Somebody who know how much charging capacity is in the car can tell if it is right or abuse of the car's electric system.