Flat 12V battery

[Roy124]

Mooly

Quote

"Without knowing the exact voltages your monitor changes states at it all becomes guesswork. What you really need to know is what the red LED illuminates at and how that is interpreted against the battery manufacturers SOC (state of charge) vs the battery terminal voltage. You will see slightly different figures quoted for this.  I would suggest around 11.8V as being a lower limit where the battery is only around 25 to 35% charged. A resting voltage of 12.5V and above shows a healthy SOC but that may be interpreted as showing 'Yellow' on your tester."

Makes sense,  unfortunately my volt meter has stopped working, powered on, correct range displayed but reading settles at zero 😞

The 12.65v was from a different forum and addressing the green/yellow drop.  AFAIK the yellow/red value was not mentioned.  As long as the READY light comes on the HV Battery will soon charge the 12v Battery.  Red and no Ready will point immediately to the 12v Battery with resort to a charger being required.  Where this happened to me it has taken only minutes for the 12v battery to recover.  So the next question might be what is the minimum voltage needed for the 12v battery to start the car systems 🙂 

[Roy124]

On 10/9/2020 at 8:21 AM, Gerg said:

You need to get some thin oil/WD40 etc. or equivalent into the lock, which is easier said than done,

Back to Gerg's earlier suggestion, rather than spray into the lock, spray the key.

[TonyHSD]

1 hour ago, Roy124 said:

Back to Gerg's earlier suggestion, rather than spray into the lock, spray the key.

Wd-40 or something similar works best for these locks either way you applied , just been outside for an hour cleaning my driveway and the car happily remained in Ready mode for the duration, lock works fine and added some more wd-40 for the next two months or longer. I done door, boot and bonnet seals with silicone all before the winter cold days started and never have any surprises. 👍🙂

[Mooly]

8 hours ago, Roy124 said:

Makes sense,  unfortunately my volt meter has stopped working, powered on, correct range displayed but reading settles at zero 😞

Check if the internal fuse has blown. Most DVM's have one. 

As to minimum voltage to power up all the systems... that is a real unknown and not easily determined. I would expect however that the systems should all power up as long as  the Battery terminal voltage holds above around 11.80 volts.  

 

[Roy124]

Mooly I will have a look, especially on the basis that it is F'd as it is even if it is displaying some numbers.

[Gerg]

 

9 hours ago, Roy124 said:

unfortunately my volt meter has stopped working

As Mooly said, it could be the internal fuse - It's all too easy, if you're not using the meter that regularly, to inadvertently plug your meter lead into the 'Amps' connection of the device, when you are actually trying to measure a voltage (this depends on the make and model of meter, of course).  A blown fuse is the price you pay for this, when the meter probes are put on to the 12v Battery.....

Also, don't overlook the possibility of one of the meter leads having gone open-circuit.  Some of the cheap far-Eastern ones don't last that long; the wire can pull off the probe end if it gets twisted too much in use.

[Roy124]

Mission failure.  Got one screw out the other screw failed to budge.  As you need to undo the screws to change the Battery that's a bit of a nonsense.  As I don't have much use for one I have ordered another cheap one.

Back on batteries. After a further 24 hours my 12v Battery state is showing Red.  I could switch on and charge or connect the charger but I have decided to leave it until tomorrow see how it works after two days. The car is sitting with bonnet open so access is not an issue.

[Mooly]

Your not having much luck are you...

I wouldn't worry at this stage over the red led showing a low Battery state, wait and see what the real voltage is when you check with the new meter. 

 

[Roy124]

15 minutes ago, Mooly said:

Your not having much luck are you...

I wouldn't worry at this stage over the red led showing a low battery state, wait and see what the real voltage is when you check with the new meter. 

 

Exactly though I will need to check tomorrow morning as we have an appointment in town later.  Give me time to recharge if the Battery is weak as the AA man had said.

[Roy124]

On 1/18/2021 at 8:05 PM, Mooly said:

Your not having much luck are you...

I wouldn't worry at this stage over the red led showing a low battery state, wait and see what the real voltage is when you check with the new meter. 

 

Exactly though I will need to check tomorrow morning as we have an appointment in town later.  Give me time to recharge if the Battery is weak as the AA man had said.

[Roy124]

Update:

The fuse in my volt meter had indeed blown but I could only find that by destroying it!

I checked the voltage yesterday.  After a 30 minute drive the charge indicator was yellow and the voltage about an hour later was 12.47v.  24 hours later the charge indicator had changed to red and the voltage was 12.17v.  I will continue to monitor the voltage drop but my initial conclusion is that the CTEK Indicator is more form over function and a waste of money.

[Mooly]

It is the actual measured voltages that are of interest. 12.47 volt for a Battery that has recently been 'on charge' is just about a realistic figure if a little on the low side, particularly if things like courtesy lights and so on are on.

12.17 volt I would consider quite low tbh.

Now is that because the SOC (state of charge) is just low to begin with or does it point to another problem such as current drain from somewhere. 30 minutes driving time wise is not enough to recharge a low Battery, and even more so if the charge into the Battery is current limited by design to prevent overheating and extend battery life. So a few unknowns here.

So if the car hasn't seen much use over an extended time period of weeks and months then the SOC will gradually fall away and not be fully replenished by short amounts of use. The results is a downward curve on the overall charge level.

 Recharging must be done with a proper charger that will not overcharge the battery and it may take 24 or hours or more to fully do this. Only when you have a known starting point (an assumed 100% fully charged battery) can you then a make a determination as to whether there is a problem.

 

[Roy124]

Mooly all true.  In my case the car has had regular runs of around 250 miles per month, an advantage of being locked down in a rural area.  The Battery had been recently recharged with a float charger and the CTEK had gone green.  The voltage drop might be normal and I will monitor it daily until we next go out.  After my previous issue the AA Man had suggested getting the Battery checked at the garage.  For obvious reasons I don't want to do this unless the voltage continues to drop off.

Regarding current drain, the car has been locked so the only drain, AFAIK, will be the alarm system.  My main point of the earlier post was to show that the CTEK indicator was as much use as a chocolate teapot.

[Mooly]

OK, so as to the CTEK do-dah, well I would say that showing Red at 12.17 volts was valid and that 12.47 volts and showing yellow was also valid. I just measured a smaller Battery I have (its a VRLA type not used for vehicle use) and it is showing an open circuit terminal voltage of 12.98 volts. It is less than 6 months old. I also have a similar but much older one (perhaps 8+ years old) that is showing 12.78 volts.

When you charge the Battery and the CTEK goes green it doesn't mean the Battery is fully charged, it just means the voltage has passed a threshold. The real test is to monitor the current into the battery from the charger and see if this falls away as full charge is approached.

Typically what happens with a current limited charger (as they all are) is that the current is initially to the chargers max output level and the voltage at the battery starts to gradually (over hours) rise as it charges. Once the batteries charging current falls below the maximum the charger can give the charger flips from a constant current to a constant voltage charge. It may now be able to maintain say 14 volts across the battery but the battery may still be drawing a couple of amps current. Over time that current reduces and reduces until it is perhaps just 0.1 amp or so, maybe even lower on small batteries. When that happens the battery is then assumed to be fully charged.

 

 

     

[Roy124]

As I said, I will keep monitoring. My charger couple of days ago went to green with the CTEK also green after 24 hrs.  The yellow range that I have found so far is very narrow which makes the monitor's utility doubtful.  This afternoon the voltage was below 12v.  It could well be that the Battery is indeed not very good.  I will monitor it over the weekend.

[Mooly]

Below 12V is definitely no good, that is an absolute. Once you reach around 11.80 volts then that pretty much signals fully discharged. Some figures quote a bit lower but either way it is right down at the wrong end of the spectrum. 

Although I have no experience with the Hybrids it would be reasonable to expect a fully charged and healthy Battery to still be capable of operating everything after several weeks... that's definitely not an unreasonable design goal. If you are seeing a fully charged Battery dip in voltage as quickly as yours seems to do then either there is a significant current drain and/or the Battery is faulty.

Also a high and constant current drain would soon cause deterioration of a good battery if it meant the battery was in a very low state of charge for most of the time.

Maybe time to have a word with Toyota and get the official line on this.

[Roy124]

Mooly, will monitor through the weekend.  No rush and plenty of time.  Thanks