Constant battery drain problem

[Cyker]

Glad you got it sorted; Thanks for posting back with how you got on!!

[delbois]

On 11/27/2021 at 3:35 PM, Chris Nutt said:

So just to follow up on this topic. I swapped out the 12v battery for a slightly higher capacity (52Ah) Bosch S4. I didn't bother about going to the dealer as the diagnostic fee was about the same as the cost of the battery - and in the case that they didn't "find" anything wrong or that the battery wasn't covered I would end up effectively paying double. I didn't have the time to mess about sitting in the dealers for hours either. Anyway, one week after the swap, I have just tested the battery voltage again and it is showing about 85-90% charge, compared to around 50% with the old battery over the same time period. Added to that over the past few days I have been using heated seats, rear screen etc a LOT more due to the sudden drop in temperature. So I think the old battery was duff - and had simply gone very low capacity and with a high internal resistance. Thanks to all on here for their inputs!

My experience with my previous Auris is it's best to change the Battery once it's been flattened. They never seem to recover full capacity. I faffed around with tests that showed the Battery to be OK yet was let down time after time after only a few days of not being used. I had a total of 3 batteries over 6 years of ownership. My current Corolla was 8 months old when I bought it and it had been sitting at the dealer's yard for weeks when I turned up for a test drive. I told the salesman I doubted it would start and he said he never had a problem before. Right enough it was totally dead. Naturally I made a new Battery a condition of sale. The Corolla battery is 45Ah vs 35ah in the Auris and considerably cheaper! 

[Red_Corolla]

23 minutes ago, delbois said:

My experience with my previous Auris is it's best to change the battery once it's been flattened. They never seem to recover full capacity.

This is true, a normal lead acid Battery isn't designed to cope with being run more than 50% flat and doing so does permanently reduce the life of the Battery. I understand that AGM batteries cope much better with being discharged and can go up to 80% without ill effects, so that might be the way to go for these hybrid cars that seem to struggle to keep the 12v Battery in a full state of charge.

[delbois]

4 minutes ago, Red_Corolla said:

This is true, a normal lead acid battery isn't designed to cope with being run more than 50% flat and doing so does permanently reduce the life of the battery. I understand that AGM batteries cope much better with being discharged and can go up to 80% without ill effects, so that might be the way to go for these hybrid cars that seem to struggle to keep the 12v battery in a full state of charge.

Interestingly the three batteries in my Auris were Yuasa AGM batteries but the replacement the dealer fitted in the Corolla isn't AGM. 

[Cyker]

Ehhhh that's not entirely true - I tend to divide lead acid batteries into two types:

Starter batteries and Deep-cycle batteries.

Flooded, Gel, AGM - These are all just different constructions, but make only a little difference to how the cell performs.

<warning, more than you ever wanted to know about lead acid batteries!>

Starter batteries use ridiculously thin lead plates - They almost look like doileys, but made out of lead. This gives them tremendous surface area which is why they can spit out hundreds of amps to start even the heaviest diesel engine, but being so thin they need to be kept as near to 100% charged as possible or they start to dissolve.

Deep-cycle batteries have much thicker and solid lead plates - They can't output anywhere near as many amps as starter batteries, but these chunky lead plates can handle lower levels of discharge without being dissolved.

Both types come in Flooded, AGM and Gel forms - We use deepcycle Gel cells with our UPS' as they have a longer life span and higher capacity than AGM, but in the old days none of that existed so you were stuck using flooded cells, but these were still deep cycle!

One of the reasons automakers are shifting to AGM is that it is spill proof and very robust - Unlike Flooded and Gel packs, the plates are clamped together with the glass mats which makes the whole thing very rigid. Its main weakness is it really doesn't like being overcharged - flooded and gel packs have more electrolyte, so if a little gets vented off from overcharging no problem, but AGM doesn't have much electrolyte and will quickly degrade if too much is released. Normally Gel and AGM have a valve to stop the vented electrolyte escaping so it can recombine back into a liquid, but will still release it if the pressure gets too high.

Flooded batteries just vent, which is why we used to have to top them off with distilled water occasionally.

I will say AGM starter batteries are slightly more tolerant of being discharged just due to the extra structural support the thin plates get from being clamped between the woven glass mats, but it still isn't good for them. For any kind of deep discharge use you really need to use deep-cycle batteries for the best longevity.

It's hard to tell the difference from the outside, but as a rule of thumb deep-cycle batteries are heavier and have rubbish amp draw stats compared to starter batteries.

 

[Red_Corolla]

@Cyker fair enough, I should have qualified by saying car batteries. I wonder why they don't fit deep cycle as standard in a hybrid. Cost, maybe?

[Cyker]

I'm not even sure if they do or not, as after we had loads of peoples' Auris Hybrid 12v batteries going flat back in the day, I thought Toyota had started using deep-cycle AGM batteries in the newer hybrids, but now I have no clue!

 

[Red_Corolla]

Just wanted to follow up on this thread with some test results of my own, as the whole discussion about parasitic drain on these cars piqued my curiosity. I have checked my own car, which is a 2.0 TS Design with keyless entry and the Battery in the boot. Tests were done using a Fluke DMM and also a hall effect clamp hooked up to an oscilloscope so that I could view the current pattern.

Some general observations:

- The time it takes for the car to fully go to sleep is 15-20 minutes. Beyond that, I saw no further change before stopping at 60 minutes.

- To get accurate measurements, it's vital to use a meter with averaging function because the current draw is non-linear, especially with keyless entry.

- If you want to stop the car from listening for the key, you have to turn the system off in the car's menu. Disabling the fob when locking does NOT stop the car from listening for it. The button sequence will kill the fob, but it doesn't tell the car to do likewise (I checked).  If you do turn it off at the car, you must subsequently hold the fob against the start button each time you want to switch on.

- The car itself knows how much power is being drawn (or added) - there's a transducer fitted to the negative terminal - so it might be possible to get some data through diagnostic apps etc, although I doubt the accuracy would rival proper test instruments.

- Keep in mind that ambient temp, state of charge of the Battery etc. all have an effect, so YMMV.

Results:

With keyless entry active: 28mA

Without keyless: 20mA

Both those figures come from my multimeter using the average setting. When keyless is active, the current jumps to about 200mA every 250ms as it polls the fob antennas. These events each last for 9ms at a frequency of 4x each second, so the net effect on Battery draw is significant but not huge. You can calculate a rough per-second average as below:

((36ms x 200mA) + (964ms x 20mA)) / 1000 = 26.5mA (not far off the calculation from the multimeter)

I have attached a screenshot from my scope to show what the current spikes caused by keyless entry look like. They completely disappear when the system has been turned off. The timespan is 1.2s and the exact amplitude should be ignored, because my current clamp cannot rival my multimeter for accuracy at these levels.

[Hibird]

The above post by Red_Corolla is a real insight into the 'Keyless Entry' burden on the 12v Battery, very interesting and with real data.

This inspired me to to turn off keyless entry on my Yaris which always seems to have a low 12v Battery voltage.

As my vehicle is used daily I am not experiencing any real issue with the 12v Battery going flat but feel if the vehicle was not used daily it would.

The results are:

Before turning off Keyless entry battery voltage in the morning after around 15 hours rest was 12.30v

With keyless entry disabled battery voltage in the morning after around 15 hours rest is now 12.55v

This is a significant difference and for the time being will stick with the disabled status.

All voltages were recorded using a Fluke DVM. I have taken no measurments to determine the load keyless entry places on the Yaris 12v system.

[Spo2]

29 minutes ago, Hibird said:

The above post by Red_Corolla is a real insight into the 'Keyless Entry' burden on the 12v battery, very interesting and with real data.

This inspired me to to turn off keyless entry on my Yaris which always seems to have a low 12v battery voltage.

As my vehicle is used daily I am not experiencing any real issue with the 12v battery going flat but feel if the vehicle was not used daily it would.

The results are:

Before turning off Keyless entry battery voltage in the morning after around 15 hours rest was 12.30v

With keyless entry disabled battery voltage in the morning after around 15 hours rest is now 12.55v

This is a significant difference and for the time being will stick with the disabled status.

All voltages were recorded using a Fluke DVM. I have taken no measurments to determine the load keyless entry places on the Yaris 12v system.

I also turn off the keyless entry  for saving Battery and security.

[Cyker]

I haven't, but I sortof want to have my cake and eat it - Want to disable the keyless entry, but not the keyless start! Unfortunately I've been told the two systems are the same system, so there is no way to disable one without disabling the other  

Thankfully I use my car regularly enough that it shouldn't be a problem, but this is good info for anyone e.g. leaving their car at a long-stay carpark!

Also means people with normal non-smart keys should be a lot less prone to the Battery draining...

 

[Deano68]

On 11/13/2021 at 4:49 PM, Chris Nutt said:

I have had my 2019 1.8 TS Excel since the end of July and it has been used very regularly. However I noticed that my dash cam (with parking mode enabled) was shutting down fairly soon (i.e. a few minutes) after turning off the car - and not the two hours it was programmed for.  On checking the battery voltage I found that the 12V battery was at 12.2V - indicating a charge level of around 50% (and this was after some decent runs of over 1 hour each). Switching the car to "Ready" made the voltage jump to approx 14.2 volts - showing the car was charging the battery OK. So it appears that the low voltage monitor on the dash cam parking power unit was switching off the camera. Firstly I thought the dash cam itself may be to blame for the low battery charge level (event though it was only set for two hours in parking mode). So I set it for zero parking monitor time and charged the battery for over a day. Today, a week after fully charging the battery and driving for over 10 hours during the week, I checked the voltage again and found it to be 12.15V. So, I decided to check the parasitic drain with the dash cam disconnected completely - and found a drain varying between 0.3 and 0.5 Amps (this was 5 minutes after locking the car and making sure everything was switched off). Clearly this is far above the acceptable level of parasitic drain (normally a few 10's of mA at the most) and clearly explains the depleting level of charge. Yes, I do have keyless entry enabled, however I had this system on my Avensis and never had these problems during 8 years of ownership. And in any case no system on the vehicle (if working correctly) should be pulling a load such as this when in sleep mode.
I'm going to give the dealer a call on Monday to get it checked over, however has anyone else on here has similar issues?

Most modern day cars have staged shut downs and don't tend to go into full sleep mode within 5 minutes, I would be checking the drain after the full shutdown has occurred, I'm no expert on Toyota's so can't tell you what the time frame is but suspect it will be longer than 5 minutes but may be wrong.

[Corollanutter]

57 minutes ago, Deano68 said:

Most modern day cars have staged shut downs and don't tend to go into full sleep mode within 5 minutes, I would be checking the drain after the full shutdown has occurred, I'm no expert on Toyota's so can't tell you what the time frame is but suspect it will be longer than 5 minutes but may be wrong.

Thansk Deano,  all that has been addressed in later posts on this thread. In my case I had a duff Battery. Since replacing it I have had no more problems. You are correct in that there are numerous staged shutdowns - the keyless entry system apparently drops to a lower polling rate after around 5 days and shuts off all sensors / transmitters other than the drivers door after 14 days. I always leave the keyless entry system active as I love this feature - as I was involved in the very early days of the keyless system design concept around 30 years ago. However I do use a Faraday box for the key 🙂

[Hibird]

Here is an update on my disabled keyless entry experiment.

The improvment in available 12v Battery voltage with the keyless disabled is interesting and positive.

Most notible is that with a Battery that I believe to be fully charged (after 40 mins in ready mode) Battery voltage is still at 12.62 volts many hours after locking and leaving the vehicle. Pror to disabling the keyless system this volage would fall rapidly to around 12.56 volts. While these differences may seem small there are significant when trying to establish the battery state of charge.

I have now installed one of those bluetooth battery monitors wired into a OBD plug to enable a simpler way to track 12v battery voltage. The unit gives a surpisingly accurate reading and very low current loading (average of around 1ma).

I will come back with any worthwhile findings.

 

 

[Cyker]

19 hours ago, Chris Nutt said:

Thansk Deano,  all that has been addressed in later posts on this thread. In my case I had a duff battery. Since replacing it I have had no more problems. You are correct in that there are numerous staged shutdowns - the keyless entry system apparently drops to a lower polling rate after around 5 days and shuts off all sensors / transmitters other than the drivers door after 14 days. I always leave the keyless entry system active as I love this feature - as I was involved in the very early days of the keyless system design concept around 30 years ago. However I do use a faraday box for the key 🙂

That's a point... I wonder if you can change the cut-off to like, 2 days or something?

Will have to try and remember to ask my dealer next time I'm there...

[Corollanutter]

43 minutes ago, Cyker said:

That's a point... I wonder if you can change the cut-off to like, 2 days or something?

Will have to try and remember to ask my dealer next time I'm there...

You can certainly ask, however I can't imagine that sort of fine tuning to be user (or dealer) adjustable as it will be baked into the system software.

[Cyker]

I only wonder as there are some things you can tweak the timeouts on, but a lot of them are dealer-only settings.

Still, no harm in the asking!

[Tel_man]

This thread is very interesting and I would like to thank all of those members who have taken the time and trouble to conduct meaningful experiments. 

On balance I feel that it would make sense to disable keyless entry for periods of no use e.g. when going away on holiday. My only problem is that I have not found out how to do this - I have checked the system settings on my Corolla and can't find anything to switch off this feature. Can anyone please let me know how it's done as I'm sure I'm missing something 😕 

[Cyker]

IIRC the setting is changed in the infotainment unit, not the dash display.

Probably in Settings, Vehicle Customization or something like that off the top of my head.

 

[Ian.S]

1 hour ago, Cyker said:

IIRC the setting is changed in the infotainment unit, not the dash display.

Probably in Settings, Vehicle Customization or something like that off the top of my head.

 

It is in the online account settings accessed via Toyota.co.uk. 

[Tel_man]

Thanks for the responses guys  - but they indicate two differing opinions. Hopefully someone who has actually achieved this will respond to clear up my confusion .....

[Cyker]

4 hours ago, Ian.S said:

It is in the online account settings accessed via Toyota.co.uk. 

Are you saying you can turn the keyless entry on and off remotely?! That doesn't seem right...

[Ian.S]

 

10 minutes ago, Cyker said:

Are you saying you can turn the keyless entry on and off remotely?! That doesn't seem right...

Yes

[Cyker]

Yeesh, glad I denied them permission to enable that stuff on mine!

 

[Hibird]

16 hours ago, Tel_man said:

This thread is very interesting and I would like to thank all of those members who have taken the time and trouble to conduct meaningful experiments. 

On balance I feel that it would make sense to disable keyless entry for periods of no use e.g. when going away on holiday. My only problem is that I have not found out how to do this - I have checked the system settings on my Corolla and can't find anything to switch off this feature. Can anyone please let me know how it's done as I'm sure I'm missing something 😕 

On my Yaris I disabled keyless enytry by selecting the 'Settings' button on the infotainment unit then 'vehicle settings' on the touch screen. I hope this helps you find it. However I can not be sure if that will work on your Corolla.