12v battery maintenance, issues, etc.

[TonyFR]

I bought a voltmeter for the socket which I started using 2 days ago and observe the following:

When I put the car into Ready mode the meter shows instantly about 11.7 (don't blink or you miss it) and goes immediately to about 14.5. Stays there more or less while I am driving.

This morning for first time I did Accessory mode (the car had fully charged overnight by the way): the meter showed instantly 11.7 and then to my surprise settled at about 12.5.  I then went to Ready when it went to 14.5 again.

Not being at all technical in this area I have no idea why it went 11.7 to 12.5 but it was a good result all the same.

 

 

 

[ernieb]

20 minutes ago, TonyFR said:

I bought a voltmeter for the socket which I started using 2 days ago and observe the following:

When I put the car into Ready mode the meter shows instantly about 11.7 (don't blink or you miss it) and goes immediately to about 14.5. Stays there more or less while I am driving.

This morning for first time I did Accessory mode (the car had fully charged overnight by the way): the meter showed instantly 11.7 and then to my surprise settled at about 12.5.  I then went to Ready when it went to 14.5 again.

Not being at all technical in this area I have no idea why it went 11.7 to 12.5 but it was a good result all the same.

 

 

 

That would suggest that initially there is a reasonable load which reduces significantly after a short period.

[IanML]

I don't have any experience with the models under discussion, but I do know that with most modern cars it is necessary to wait a good long time (maybe 30 min) from unlocking the car, with the bonnet open and the doors shut, before taking a Battery reading.  It's the only way to get a valid no-load value for voltage, SOH and/or current drain, as the woken-up circuits need a longish interval to go to sleep again.

Clearly, no-one will want to sit in the car with nothing on and the doors shut for half an hour, which is why I said with the bonnet open.  Open the bonnet and, if the alarm monitors the bonnet switch, you start the waiting period again.

[Gerg]

5 hours ago, ernieb said:

That would suggest that initially there is a reasonable load which reduces significantly after a short period.

On our Auris hybrid, when the brake booster operates on first opening the driver's door, the load on the 12 volt Battery is just over 18 amps.  This only lasts a few seconds until the brake system is up to pressure, the current then drops to 2 amps.

When the car is put into 'Ready', a 20 amp current is drawn briefly. On the Auris, with the 12 volt Battery previously sitting at 12.1 volts, the Battery is then charged with a 5 amp current, which lowers to 2 amps after a second or so. After another second a 1 amp current is all that is being put into the battery. 

Note:  in this case the system was put into 'Ready' with 'EV mode' selected, as I didn't want to put the engine through a warm-up phase needlessly.

As TonyHSD has mentioned before, it's these initial loadings that can be what drags the 12V battery down to the point where the car can't start, even though the doors had unlocked correctly, interior light had come on, etc.

Well, that's how I've understood it.

[Derek.w]

The 11.7 voltage to me suggest the current capacity of the Battery is low if you using a CTEK charger then charge it using bike mode.

I prefere to check voltage using a Battery Monitor you can do this without opening the car.

[ernieb]

Does this connect to the OBD port?

9 hours ago, Derek.w said:

The 11.7 voltage to me suggest the current capacity of the battery is low if you using a CTEK charger then charge it using bike mode.

I prefere to check voltage using a Battery Monitor you can do this without opening the car.

 

[ernieb]

So I bought a Noco Genius 5A charger and got the Battery eyelet terminal connector. Just fitted the eyelet terminals to the 12v Battery having clamped the Battery lug to ensure when I removed the nut that tightens the connector to the lug to fit my eyelet terminal cable that the power was not disconnected from the car. The eyelet terminal cable is short but has a locking connector that fits the charger output cable. I ran a mains cable from the garage under the rear passenger door, just compresses the seal, and connected up, selected AGM battery and off it went. After a couple of hours the battery was fully charged so obviously not in a bad condition.

Quick update: the voltage before I started was 11.7v after letting the car soak in accessory mode or awhile it was 12.2v, started at 12.4v.

[Rigsby]

The RAV4 12v Battery capacity is around half of my previous 2 cars, my last car was a Jaguar XE R-Sport and the Battery was  95Ah and the one before that 80Ah.

I understand the Hybrid system relies less on the 12v Battery but is the OEM 45Ah really up to the job, and would there be any pitfalls to upgrading to a larger Ah (excluding cost)

[philip42h]

36 minutes ago, Rigsby said:

The RAV4 12v battery capacity is around half of my previous 2 cars, my last car was a Jaguar XE R-Sport and the battery was  95Ah and the one before that 80Ah.

I understand the Hybrid system relies less on the 12v battery but is the OEM 45Ah really up to the job, and would there be any pitfalls to upgrading to a larger Ah (excluding cost)

Yes ...

A traditional ICE powered car has a starter motor (and alternator) and needs a significant current to turn over the engine to get it started.

A Toyota hybrid uses the 'massive' traction Battery to start the ICE so, to that extent, a traditional starter Battery is redundant.

So, yes, a 45Ah auxiliary Battery is up to the job.

The question arises as to how long you can leave the car standing and still have enough power to get going again - a bigger battery could stand idle for longer. If you use the car once or twice per week then you should never have an issue; if you leave the car standing idle for six weeks you are likely to get to recharge the auxiliary battery in order to get going again.

If you need longer idle standing times you can get higher powered batteries that fit in the space available but I strongly suspect that the vast majority of us use the car sufficiently often for the auxiliary battery size not to be an issue.

[ernieb]

Philip, agree that the Battery capacity is easily up for the job. What I’ve noticed over the last few days of playing around and monitoring the Battery is the difference in the  voltage the car delivers against the voltage a dedicated AGM external charger uses.

In the car I’ve never noticed the voltage go above 14.4v and typically it sits at 14.2v. The NOCO charger I bought delivers 14.8v in the AGM mode. I’ve checked out a few on line AGM specifications and the recommendation is between 14.6 - 14.8v.

What are other peoples observations on the in car charging voltage?

If my observations are typical then it would suggest that the car is not providing enough charging voltage to fully charge the 12v Battery, this would seem to be strange.

[philip42h]

As I understand, when performing a full charge from a state of discharge a standard lead acid Battery is best charged at 13.8v – 14.4v, whereas AGM batteries are designed to able to accept a higher voltage of 14.6v – 14.8v. And that is what our Nocos deliver if we set them up accordingly. But:

• We would never expect to perform a full charge from a state of discharge using the in-car system. If the auxiliary Battery got that flat we'd use a mains charger.
• Anything over 13v will fully charge a 12v Battery - it's just that a lower voltage is slower, while a higher voltage is quicker. The lower voltage is always 'safer'.

Personally, I never change the Noco from it's default setting to accelerate the charging of an AGM battery - this saves me from bothering which type of battery needs charging. The standard lead acid setting will work just fine with an AGM battery (unless it's completely flat), while the AGM setting is 'too pushy' for a standard lead acid battery.

[ernieb]

The standard lead acid Battery setting on the NOCO gives 14.5v. I’ve always assumed the difference in the voltages is not to do with the speed of charge but the chemistry involved in the Battery. The AGM Battery needing the additional voltage to complete the full charge.

It still begs the question why the car never gets anywhere near 14.5 volts let alone 14.8 volts.

[nlee]

Is the Battery in our cars AGM? I thought I'd read somewhere it was a standard Battery, so when I charged last week I put the charger on standard setting.

@Derek.w why do you recommend charging in bike mode? I assumed that would be 6v but my thinking may be well out of date.

Another observation from having the gizmo plugged in while on a 50 min drive yesterday. For the first part of the journey, it was showing around 14.4v. Towards the end and for the last 10 mins or so, I glanced down and it was showing 12.4v. Would this suggest the car adjusted the output voltage because the Battery was full? Does an alternator on a standard car do that? When I pulled up at home and reversed onto the drive, it when back up 14.4v.

[nlee]

Another thought. I have kept my jump starter pack in the compartment with the charger lead under the boot floor. Thinking about it, I presume if the Battery is too flat to allow opening the doors with the fob, you can't open the boot and it will be a right PITA to get to it. Might have to rethink that one.

[IanML]

1 hour ago, nlee said:

Would this suggest the car adjusted the output voltage because the battery was full? Does an alternator on a standard car do that?

Yes, a lot of modern cars' alternators do that, as it saves fuel.

[JARC1]

21 hours ago, philip42h said:

Yes ...

A traditional ICE powered car has a starter motor (and alternator) and needs a significant current to turn over the engine to get it started.

A Toyota hybrid uses the 'massive' traction battery to start the ICE so, to that extent, a traditional starter battery is redundant.

So, yes, a 45Ah auxiliary battery is up to the job.

The question arises as to how long you can leave the car standing and still have enough power to get going again - a bigger battery could stand idle for longer. If you use the car once or twice per week then you should never have an issue; if you leave the car standing idle for six weeks you are likely to get to recharge the auxiliary battery in order to get going again.

If you need longer idle standing times you can get higher powered batteries that fit in the space available but I strongly suspect that the vast majority of us use the car sufficiently often for the auxiliary battery size not to be an issue.

My last car was a renowned model for heavy Battery discharge (parasitic may be). I used a CTEK MS 7 charger           re-conditioner  at least once per week and for at least 24 Hrs. It kept everything under control and cured the other renowned problem with the model of producing many many warnings and codes. I have no idea what a NOCO is ........... probably because I am (as my daughter tells me) a dinosaur.  I am only a young 72 years but am not educated on modern day phrases and sayings, especially when it comes to Smartphone language etc, etc,.

Best Wishes and Regards, John

[Gerg]

20 minutes ago, JARC1 said:

I have no idea what a NOCO is

NOCO is a competitor of CTEK's.

From what I can see they are the 'new kid'.

Smaller and with a generally higher specification for a given price.

Like CTEK - stocked in Halfords, if you wanted to view one.

HTH

[ColinB]

2 hours ago, nlee said:

 

@Derek.w why do you recommend charging in bike mode? I assumed that would be 6v but my thinking may be well out of date.

Bike batteries are 12V, but smaller capacity, so charging rates are generally lower. On my bike I have an Optimate charger permanently connected, which maintains the Battery rather than overcharging it, I use my car more so don't need to use a permanent charger although I do have a solar one for extended periods of not using it.

[philip42h]

2 hours ago, nlee said:

Is the battery in our cars AGM? I thought I'd read somewhere it was a standard battery, so when I charged last week I put the charger on standard setting.

Yes, the auxiliary Battery in the boot should be AGM. The OEM replacements are, and AGM is appropriate for a Battery stowed within the car.

You can do no harm by charging it on the standard setting - you'll just be using a fractionally lower voltage so the charge may take fractionally longer.

And yes it would be more sensible to stow the jump starter pack somewhere that you can access just using the mechanical key and manual opening ... 😉

(and, hopefully, never, ever use it!)

[ernieb]

Mines definitely an AGM it’s written on the Battery. 

[JARC1]

2 hours ago, Gerg said:

NOCO is a competitor of CTEK's.

From what I can see they are the 'new kid'.

Smaller and with a generally higher specification for a given price.

Like CTEK - stocked in Halfords, if you wanted to view one.

HTH

From what I can see this is a stand alone (not needing mains current to start a car) item. The CTEX although it will start a completely flat Battery, does need a mains connection to work. This is fine for keeping a Battery in good condition, but will not work in an emergency away from home.

What model NOCO model would be recommended for me to purchase . I presume I will be told the highest rating model so as I have no problems of not enough power.

Many thanks and Best Wishes, in anticipation of required help.  , Cheers , John

[ernieb]

This is what I bought:

https://smile.amazon.co.uk/gp/product/B0828HLDZC/ref=ppx_yo_dt_b_asin_title_o02_s00?ie=UTF8&psc=1

plus the M6 terminal kit:

https://smile.amazon.co.uk/gp/product/B004LWQ35Y/ref=ppx_yo_dt_b_asin_title_o02_s01?ie=UTF8&psc=1

this is a 5A model and more than adequate to charge the RAV 4 Battery.

[philip42h]

35 minutes ago, JARC1 said:

What model NOCO model would be recommended for me to purchase . I presume I will be told the highest rating model so as I have no problems of not enough power.

I went for the NOCO Boost Sport GB20. It is way powerful enough to boost a hybrid auxiliary Battery so that you can get into Ready mode. There are much more powerful ones if you need to start large diesel powered trucks but I don't ... 😉

[B Voros]

Hello all, that 14.4v in Ready mode is the charging voltage, you can see the open circuit voltages for a 12v Battery in the picture below.

[ernieb]

Is this the same for an AGM Battery or would that be different?