12v battery maintenance

Interestingly, I just found this in the user manual:

To prevent damaging the vehicle (M20A-FXS engine)
The exclusive jump starting terminal is to be used when charging the 12-volt Battery from another vehicle in an emergency. It cannot be used to jump start another vehicle.

Stuart,  simply because the Hybrid system is not designed to turn over a starter motor. 

Hi Roy, I am just looking for the easiest place to attach my Ctek charger when we leave the car to go abroad on holiday. Sounds like I can attach it to the jump start terminal under the bonnet rather than remove the side panel in the luggage compartment and have cables coming out of a window.

The car is parked in a carport so a solar charger won't work I think.

Stuart,  I don't know.   The jump start terminal is what you would use for a Battery pack.   For the CTEK charger I have gone for hard wiring to the Battery. 

In your case,  with the car in the carport,  using the CTEK and letting it run on a float charge would keep the Battery charged but connecting directly to the battery would need you to run the cable into the locked car.   The cable is thin,  you could probably just run it through the door. 

Someone did suggest fitting a solar panel on the garage/carport roof. You could then used the OBD port. 

Thanks for your help Roy and David 

On 8/24/2022 at 11:25 AM, Roy124 said:

Stuart,  I don't know.   The jump start terminal is what you would use for a battery pack.   For the CTEK charger I have gone for hard wiring to the battery. 

In your case,  with the car in the carport,  using the CTEK and letting it run on a float charge would keep the battery charged but connecting directly to the battery would need you to run the cable into the locked car.   The cable is thin,  you could probably just run it through the door. 

Someone did suggest fitting a solar panel on the garage/carport roof. You could then used the OBD port. 

CTEK or NOCO charger has a good controller although CTEK can be very hot after a while. They are better than most unknown brand solar panel charger.  You only need charging the Battery if you leave the car for weeks. If it is less than 2 weeks, don't bother.  I never need to connect any charger in the past 6 years until COVID19 came and I did not drive for couple of weeks and start to worry if it may need charger.  Just drive the car regularly, once a week for at least 30 minutes, you never need charger. 

But does the hybrid Battery continue to charge the 12volt Battery even though the engine is not ticking over? So long as it is Ready mode is it charging the 12volt Battery?

Similar topics merged.

10 minutes ago, GrahamJGriffiths said:

But does the hybrid battery continue to charge the 12volt battery even though the engine is not ticking over? So long as it is Ready mode is it charging the 12volt battery?

I always thought it did, but according to others on here it doesn't always; If there's a volt meter plugged into the 12v socket it should show 13-14v+ when the battery's charging, but according to a few people it doesn't, not all the time anyway.

The hybrid Battery will only charge the 12v Battery if it requires charging.  Once a certain voltage is reached charging of the 12v Battery will stop, this then reduces the drain on the hybrid battery.   Frequent trickle charging of the 12v battery is a good idea as it maintains the voltage in the battery thereby reducing the load on the hybrid battery allowing more of the stored energy to be use to propel the vehicle which helps to reduce fuel consumption.

Here is the official maintenance procedure for both HV and 12V Battery. It is USA gov. Website, but still relevant to our car in Europe.

https://static.nhtsa.gov/odi/tsbs/2019/MC-10154807-9999.pdf

I was sitting in Morrison's car park this morning while my better half was in for supplies, probably for about 30mins.

Rather than switch the car off I switched off the heating/aircon, etc and left it on ready. No problem and something I may do as the opportunity arises 👍

4 hours ago, AisinW said:

Here is the official maintenance procedure for both HV and 12V battery. It is USA gov. Website, but still relevant to our car in Europe.

https://static.nhtsa.gov/odi/tsbs/2019/MC-10154807-9999.pdf

Very good information.
Thank you. 👍

Wow they really write those step-by-step to be idiot-proof don't they  

I do wonder how many of them actually follow those instructions tho', given how most of us have been finding the PDI hadn't been completed on our cars on collection...! (e.g. protective films not removed, QR code stickers not removed and the tyres still at storage pressures! (3+ bar!))

The hybrid cars rarely stayed on dealer parking lots more than 2 months. The worse part is, buyers have to bid to the highest price way above MSRP/sticker price. 

Have had my 2023 TS for just under two months and have done about 1300 miles. Came back from a 2.5 hour journey on mainly motorway and stopped at services for essential supplies. While wife was shopping I remained in the car and had the radio on with the car in Accessory mode. After two minutes I got a low Battery warning and after a further two minutes it auto shut down. On testing back home the 12v Battery showed 12.3v with the engine off and 13.4v with the engine on. Are these normal readings or is the 12v Battery underperforming? I don't remember ever having a "low battery. Turn power off" message with my other two hybrid Corollas.

I sometimes leave the power switched on for a couple of hours if the Battery voltage is a bit low. If you turn the heater off the engine doesn't run for long. The 12 volt Battery will charge from the traction Battery. The engine will probably run for a few minutes per hour just to charge the traction battery.

1 hour ago, RabButler said:

On testing back home the 12v battery showed 12.3v with the engine off and 13.4v with the engine on. Are these normal readings? 

Given Dala's table it looks fine. 

Just taken a reading on mine after 24hrs - 12.35v. Yesterday, a few minutes after switch off it was 12.47v.  You can expect a drop over 2 hrs after switch off then the discharge becomes very little. 

My Battery is now almost 8y old. Fortunately, i never have a problem to start the car up. The voltage on ACC mode is never below 11.7V. The open voltage is between 12.3-12.7 at all time. I noticed that Auris 2 never have issues with Battery draining. After about 20 minutes, all lights are off and no more current flow on the interior. The  dome fuse has no voltage drop between 2 terminals. We can detect how much current leak/flow from the voltage drop between fuse legs. Corolla must have similar behaviour but the emergency call system may drain Battery. Check and update it before warranty is over.

When I checked mine after been parked up for a couple of days it's  11.64v and there is a draw of 0.02 amps with every thing switched off.

Car might be used once or twice a week with approximately 9 miles clocked up per week .

John, assuming your reading is accurate and the draw is as you say, that suggests your Battery was below 12v when you last used it. 

I suggest you need to do some more checks.

6 hours ago, Roy124 said:

John, assuming your reading is accurate and the draw is as you say, that suggests your battery was below 12v when you last used it. 

I suggest you need to do some more checks.

In ACC mode it is normal below 12V. ACC mode take a lot of current and it is normal that the voltage reading will drop significantly. As long as it can start and the voltage is never drop below 10V, it can start and has no error. If we turn the headlight on in ACC mode, we usually will have 11.3-11.5V with halogen bulb. May be higher with LED or xenon bulb. 

Whenever the voltage dropped  below 10V, it will trigger C1241 code. It is not check engine light and only capable enough software+OBD2 can see it. I had it when the Battery terminal was loose.  

@tfc you should try removing the D/C cut fuse, and check again after 1 hour. I think you should no longer read 20mA current flow. 

@AisinW, unless I am reading @tfc post wrong, he was not in ACC, so what you say in paras 1 and 2 may be true but not relevant. The last paragraph might have a bearing but measuring such a small current drop, or lack of, might be difficult. 

My bad, i use ACC because i use OBD2 scanner. With voltmeter, my Battery is 12.3-12.9V. @tfc if the Battery below 12V when everything is off, it is not good. Below 11.8V, sulphation is permanent.