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I have real problem wth my brand new 12 V battery.
My car NX300h (2018) often stay in idle mode for 2-3 days and it couse total depletion of 12 V battery.
I have 12 V booster but using it every time to start the engine is really annoying.
What sensors, equipment, other stuff is using 12 V Battery in idle mode? Anyone has a list?
What can I switch off to save the battery?
The 2018 NX300H Owners Manual lists 4 operating modes on Page 170:
Off
Auto Power Off
Accessory
On (Ignition On)
I did not fine any reference to "Idle Mode". Do you equate Idle Mode with Off Mode?
These cautions were copied from page 171:
To prevent 12-volt battery discharge . . . . .
●Do not leave the power switch in ACCESSORY or ON mode for long periods of time without the hybrid system on.
●If “ACCESSORY” or “IGNITION ON” is displayed on the multi-information display while the hybrid system is not operating, the power switch is not off. Exit the vehicle after turning the
power switch off.
●Do not stop the hybrid system when the shift lever is in a position other than P. If the hybrid system is stopped in another shift lever position, the power switch will not be turned off but instead
be turned to ACCESSORY mode. If the vehicle is left in ACCESSORY mode, 12-volt battery discharge may occur.
By term "Idle mode" I mean that car is turned off, locked and key is far away. Probably better term is "Sleep mode" instead.
I am aware that alarm is on normally when car is locked. Also I heard that some kind of sensing mode is on what allow to unlock the car by tuching handle - sensors continuously looking for smart key.
Just need a full list of such stuff and what I can switch off to save 12 V battery.
Such a "list", if it existed (which I doubt) would not be useful, because you either have a defective battery or an "Off Mode" parasitic current more than 10 times the maximum specified by Toyota/Lexus. This could be the result of:
** A defective module, such as an audio amplifier that continues to draw current when turned off;
** Equipment that was installed by the dealer, such as a remote starter or anti-theft tracking device;
** After-market modules not supplied by Toyota.
A good auxiliary 12V battery should have a storage capacity of 30-60 Amp-hours. Toyota specification for maximum permitted Off-Mode current is 50mA (0.05 Amps).
This means time to fully deplete the battery should be more than 30 days (40 Amp-hours / 0.05 Amp = ~800 hours). To deplete a good battery in 3 days (~72 hours) would require a current of more than one-half Amp, which should be relatively easy to isolate.
Thank you for the link.
Car 12 V Battery is one month old (brand new). It was purchased specialy for this model of Lexus as per supplier catalogue (brand VARTA).
Before replacing I did Amperage measurements in off-mode:
- Disconnected negative clamp from Battery;
- Connected Tester between clamp and Battery contact;
- Start button switched to OFF;
- Closed door and locked it;
- Took smart key far from car;
- Waited for 15 min.
The Tester shown me arround 10 mA. Maybe worth to test also new Battery?
What is interesting that my old Battery still show 12.2 V after one month in garage so probably this replacement was not needed.
The standard automotive battery has six cells, each with 2.1 volts (open load measurement) at full charge. A car battery is considered fully charged at 12.6 volts or higher. When the battery’s voltage drops, even a small amount, it makes a big difference in its performance. The table copied below shows how much energy remains in a battery as the open load battery voltage reading changes (valid only at 20C-25C).
Try intentionally leaving the map lights on. This should cause a current drain of 50mA to 100mA. If there is only a small change, or no change, in the time required to deplete the battery, it indicates some other cause is more dominant. Even new batteries are sometimes defective or suffer early-life failure.
Thank you for the explanation.
It is useful information but I do not think it is my case. After replacement I have chacked the old battery after one month and I found 12.4 V still loaded.
So I do not believe that two batteries were faulty. Most probbly there is parasytical current flow somewhere. Try to find it, thanks for suggestions I got here in this forum.
But if anybody has more ideas I would appreciate to hear.
Thank you for the explanation.
It is useful information but I do not think it is my case. After replacement I have chacked the old battery after one month and I found 12.4 V still loaded.
So I do not believe that two batteries were faulty. Most probbly there is parasytical current flow somewhere. Try to find it, thanks for suggestions I got here in this forum.
But if anybody has more ideas I would appreciate to hear.
does your current tester have a max mode? Just disconnect + side of battery and test the current draw when car is lock, if a few mA, then put the tester in max mode and read the max reading a day later. If still a few mA, the battery or the alternator is defective. Good luck.
That is what I thought too. Most probably I do not see full picture.
My tester does not have MAX function so now I am looking for better one.
Best would be to log all voltages every second, for instance.
Would be great to write all readings somewhere with time stamp.
Sorry for late post - had some problems with health.
Recently I did tests with amperage while car was in off mode
Test No 1.
Locked a car, took smart key far away and after 30 min measured Currency. I got 0,35 A of stable Currency !
Test No.2
Tried to solve this issue. Again, locked a car, took smart key far away and waited 30 min. Then I connected my Tester between battery "-" and car body and set it in Currency mode. Then I took and put back all the fuses one by one. I did not find any of them being a reason of 0,35 A Currency.
I know that normally it should be around 0,07-0,08 A in Off mode.
07-26-22, 09:57 AM
12 V Battery deplete in idle mode
