12v battery maintenance, issues, etc.

[MCatPG]

19 hours ago, Stopeter44 said:

OK, I think that wraps it up, nobody has commented on the dealer's position on the issue.

I'm only replying because nobody else has. There may be others with more knowledge and a different opinion but I think the dealer is wrong.

Any conventional Battery can be tested in several ways but there are two common methods. The first is with a device which imposes a heavy load (high amperage). This is usually a carbon pile tester. My favourite Battery guru says these have a mixed reputation for accuracy and can cause damage especially if there is one cell which is deteriorating more than the rest. If the dealer was planning to use one of these testers the delay wouldn't matter but I wouldn't want my Battery tested that way.

The second method is to charge the battery to full capacity (I allow at least an hour on steady float), then disconnect the charger and all loads, leave it for a short time, measure the standing voltage, leave it for a longer time - opinions differ about how long - and then measure the voltage again. Ideally a good multimeter should be used for the measurements. A new battery which has been stored properly since manufacture should hold the post-float standing charge or something very close to it for a long time. A battery which is on its last legs will start dropping voltage quite soon. An extremely badly damaged battery will either not reach float charge or will not hold the charge at all - you can literally watch the voltage dropping on the meter. Most batteries will be somewhere in between. 

If the dealer uses the second method with the battery disconnected from the car at the terminal posts it would not matter that there had been some time since the discharge incident. If the battery is still in good condition it will hold its charge for many days. If it has been damaged it won't. If the dealer is willing to use this test method, and you are willing to be without the car for perhaps a day, then the test can be done at any time. Or you could do it yourself and take photos of the readings.

[Stopeter44]

@MCatPG Nice post above. I don't know which method the service department (SD) was going to use, but I expect the Battery would be left in situ. The SD told me they check/test the Battery when the annual service is carried out. They have a Toyota supplied system that tells them if the Battery needs replacing.

The explanation was succinct, but it appeared that this Toyota tester, allowed 5 different statuses (is that the right plural ?). I expect that the battery is sub optimal, but within tolerance. OTOH, the car is under guarantee, and I don't want to replace the battery, without the aval of Toyota. I'm afraid that the guarantee may be compromised.

[MCatPG]

@Stopeter44 Thanks.

Leaving the Battery in situ is OK but disconnecting or isolating it is essential. You can't test a Battery using the voltage drop method if there is any load on it, even if the load is very small, because the load will always cause a slight voltage drop. If the load is small and the voltmeter is crude you might not notice the load-imposed drop but such a meter is inadequate for the job, you need a multimeter or a purpose-made device which will in fact be just a sensitive voltmeter in a different sort of case. All boats, aircraft, railway locomotives, and most other vehicles have (or should have) Battery isolation switches. Cars used to have them, a long time ago, but they don't now, so you have to physically disconnect the battery.

I am interested in Toyota's system for testing batteries. If anyone can find out about this I would like to know how it works. @Devon Aygo perhaps?

Plural of status - I have always used just "status" and worded the rest of what I am saying to suit. So for your sentence I would have said "5 different status values", but that's just me, and here's another way of looking at it:

 https://www.grammarbook.com/blog/singular-vs-plural/plural-of-status/

[anchorman]

8 hours ago, MCatPG said:

I'm only replying because nobody else has. 

 

Perhaps somebody did and you didn’t notice it 😉

[MCatPG]

36 minutes ago, anchorman said:

Perhaps somebody did and you didn’t notice it 😉

A quirk of the timing of the notification to my inbox? Or something 

Was the dealer right? Hmmm.

'If you charge a Battery for 24 hours then test it, invariably it will test ok.' That is true for any Battery that isn't completely wrecked (for example with a completely failed cell) but that is not how to do a voltage drop test. For a valid test the Battery must be disconnected, charged, rested (some say settled), the voltage measured, then left for some time, and the voltage measured again to see if it has dropped. A battery which is incapable of holding a charge might appear to be OK if you only test it immediately after charging and don't do the "wait and measure again" part of the test, and if that is all the dealer is offering to do then I can see why they might say a delay between the incident and the test makes the test useless.

But the dealer is missing the point. What we are really trying to test is the battery capacity, which is the amount of current it can accept, store and deliver. Battery capacity is conventionally measured in Amp hours (Ah). A 100 Ah battery is designed to hold and deliver 100 Amps for 1 hour (or 1 Amp for 100 hours) at its design voltage*. A 12V 100Ah battery is designed to deliver 12V x 100A x 1 hour = 1.2kWh of current, and that is the true measure of its capacity. A disconnected 12V 100Ah battery should show a correct voltage (usually around 12.7V) immediately after charging. If it is still showing the same voltage many hours later this would suggest it still has its full capacity. If that same battery is damaged it might show 12.7V immediately after charging but several hours later it might show only 12.2V which shows that it cannot hold its State of Charge and has lost some of its capacity. An indispensable part of a voltage drop test is the delay between the measurement immediately after charging and the second measurement and as I said earlier opinions differ about how long that delay should be.

*In fact any conventional (not lithium) battery can only deliver about 50% of its stated capacity without becoming damaged. 

[Derek.w]

A load test is a load placed on the Battery for a few seconds then the voltage drops.

Load dependant on Battery capacity and its lowest voltage point.

When the load is removed its its then down to the time it takes to recover voltage goes up.

If all goes well it pass some load testers are avaible with a pass/fail indicator you just select a Battery type & load from within the test kit.

[anchorman]

4 hours ago, MCatPG said:

A quirk of the timing of the notification to my inbox? Or something 

Was the dealer right? Hmmm.

'If you charge a battery for 24 hours then test it, invariably it will test ok.' That is true for any battery that isn't completely wrecked (for example with a completely failed cell) but that is not how to do a voltage drop test. For a valid test the battery must be disconnected, charged, rested (some say settled), the voltage measured, then left for some time, and the voltage measured again to see if it has dropped. A battery which is incapable of holding a charge might appear to be OK if you only test it immediately after charging and don't do the "wait and measure again" part of the test, and if that is all the dealer is offering to do then I can see why they might say a delay between the incident and the test makes the test useless.

But the dealer is missing the point. What we are really trying to test is the battery capacity, which is the amount of current it can accept, store and deliver. Battery capacity is conventionally measured in Amp hours (Ah). A 100 Ah battery is designed to hold and deliver 100 Amps for 1 hour (or 1 Amp for 100 hours) at its design voltage*. A 12V 100Ah battery is designed to deliver 12V x 100A x 1 hour = 1.2kWh of current, and that is the true measure of its capacity. A disconnected 12V 100Ah battery should show a correct voltage (usually around 12.7V) immediately after charging. If it is still showing the same voltage many hours later this would suggest it still has its full capacity. If that same battery is damaged it might show 12.7V immediately after charging but several hours later it might show only 12.2V which shows that it cannot hold its State of Charge and has lost some of its capacity. An indispensable part of a voltage drop test is the delay between the measurement immediately after charging and the second measurement and as I said earlier opinions differ about how long that delay should be.

*In fact any conventional (not lithium) battery can only deliver about 50% of its stated capacity without becoming damaged. 

I’m quite well aware that a “completely wrecked battery” won’t test ok but I’m not sure anybody has presented one completely wrecked or even mentioned it.   You’re obviously no fool but I’ve got a City and Guilds distinction in Battery and charging systems, I own a Battery analyser and a drop tester so can generally find my way around a charging and starter system.  I find that theorising has to be balanced with what is practical and as batteries and other components age you can’t expect perfect bench results in practice and you can’t have a workshop full of vehicles under lengthy theoretical tests.  Experience tells you if you’re going to have a problem after appropriate tests and you can get it fixed and move on to the next vehicle without pondering over differing opinions about the method.  

[chazbri]

Has anyone been given this advice from a Toyota dealership to leave the car in ready mode for an hour each week when it's not being used much? My Cross was in for repair for a week having some damage repairs and when it was ready it wouldn't start. The body shop charged the Battery and everything was OK with the car then after an enquiry with my local dealership was given the above advice. Any thoughts?

[Stopeter44]

1 hour ago, chazbri said:

Has anyone been given this advice from a Toyota dealership to leave the car in ready mode for an hour each week when it's not being used much?

No, but similar advice is common place on this forum. Such as, leaving the car in ready mode whilst waiting for someone, for example. Or, not turning the car off before the engine stops when leaving the car parked for a while. This is because the traction Battery keeps the 12v Battery charged (or not, when the car won’t start).

[Russ Taylor]

So my Yaris Cross is 13 months old and has 11500 miles fairly evenly spread. About 200 miles a week over 4 days (try to use our Panda equally in trips but YC for longer trips) and I’ve never had a starting issue. My friend around the corner has a YC and uses his less and has had a few “non start” occasions. He has purchased a Noco and has successfully (had to) used it.

We just left our YC for 8 days and I took the precaution of turning privacy on so that there was less communicating with the mother ship when we were away. Came back and turned on and no issues at all. When first into ready mode the car didn’t even start the motor to charge the Battery for some minutes until we were driving and calling for the motor. 

So all is still well and I haven’t panicked and bought a Noco. What I don’t know is how beneficial turning on Privacy was in helping. Does anyone have an idea?

[Stopeter44]

1 minute ago, Russ Taylor said:

We just left our YC for 8 days and I took the precaution of turning privacy on so that there was less communicating with the mother ship when we were away. Came back and turned on and no issues at all. When first into ready mode the car didn’t even start the motor to charge the battery for some minutes until we were driving and calling for the motor. 

An interesting thought. There's no mobile coverage, at all, in the underground parking garage I use, if my Yaris is trying to communicate with Toyota via the e-sim, that could be an issue.

[Roy124]

On 7/8/2023 at 2:36 PM, Stopeter44 said:

 I also notice the inexpensive ones, at least, do not have very long cables, which might be a problem on the Yaris ?

Why?

You fasten the positive clip to the positive blade terminal in the fuse box and negative to the bodywork. 

[Roy124]

7 hours ago, chazbri said:

Has anyone been given this advice from a Toyota dealership to leave the car in ready mode for an hour each week when it's not being used much? My Cross was in for repair for a week having some damage repairs and when it was ready it wouldn't start. The body shop charged the battery and everything was OK with the car then after an enquiry with my local dealership was given the above advice. Any thoughts?

Yes, it was published by Toyota in April 2020 after Covid lock down though it was not widely promulgated AFAIK.

[TopGeek]

It seems to me that the key factor in the state of charge of the 12-volt AGM Battery is the amount of driving time. Those who do daily long distances will charge their batteries to 80-100% capacity and probably never encounter the dreaded 'no start' situation. People who do shorter distances will probably be driving around constantly with the Battery never exceeding 50% of its capacity - but no-one will ever know. However, they may well encounter the 'no start' situation if they leave the car unused for a coulple of weeks. It's those who only use  their vehicle for short trips that are most at risk because their batteries probably never exceed 25% charge. Consequently, their static discharge time will be even shorter. Leaving the car in 'Ready mode' for an hour may offset the risk to a degree but it will not charge the Battery to full capacity.

The best option IMHO is to use an intelligent charger (designed for AGM batteries), on a regular basis, in order to keep the battery close to it's full capacity. Whether you connect the charger direct to the battery or to the jumper point is irrelevant although the jumper point charge current should not exceed 5 amps.

It's worth mentioning that the jumper point purpose in Toyota hybrids is purely to raise the battery voltage to a high enough level to power the on-board electronics. Once the 'Ready' light comes on, the jumper leads can be disconnected.

There is no high current requirement because the 12-volt battery does not start the engine. There is no starter motor; instead the 400-volt lithium battery spins the electric motor mechanically connected to the engine, So, if you buy a jumper pack, you don't need a high-current unit like you would need for a conventional petrol or diesel vehicle. All you need is a small jumper pack that will deliver 12-volts at low-current to the jumper point.

 

[CPN]

2 hours ago, TopGeek said:

The best option IMHO is to use an intelligent charger (designed for AGM batteries), on a regular basis, in order to keep the battery close to it's full capacity.

That's fine, however, many of us have found that most of our cars do not have AGM batteries.

[Stopeter44]

7 hours ago, TopGeek said:

All you need is a small jumper pack that will deliver 12-volts at low-current to the jumper point.

So Nico GB40, or equivalent, is fine ?

[Jasper.]

28 minutes ago, Stopeter44 said:

So Nico GB40, or equivalent, is fine ?

That's what I have and I've used it a couple times on mine when it's failed to start. 

[Graham47]

9 hours ago, TopGeek said:

Leaving the car in 'Ready mode' for an hour may offset the risk to a degree but it will not charge the battery to full capacity.

@TopGeekDo you have evidence to back this up ?
What is the charging rate of the dc-dc converter ?

[CruxisCore]

By the graphs it seems that when it's actually doing the most it can, we're looking at like 14,3-14,5v when charging and then theres the seperate lower smart charging thing that pushes like 12,7-13,5v. So probably pretty usual cycle of charging hard and then just more of a maintenance trickle charge

I dont think there is any reason to believe actually driving does anything more. Since regardless the power comes from the hybrid Battery and when that gets low, the ICE starts up to charge the hybrid Battery. There's a reason why alternators charge way more when driving, but none of that applies to how these hybrids charge. Of course, in a whole lot of cases short trips usually equal in short time in Ready-mode, while long trips equal more time in Ready-mode. Exceptions ofc exists in like heavy traffic, where distance may be short but you are still stuck in Ready-mode for a long time.

EDIT: That said, I guess it's possible that it will only go to the "smart charge" state when stationary in Ready-mode and push that +14v when theres more excess power coming into hybrid Battery. Cos surely driving around due to regenerative braking gets more energy and more efficiently than just running the ICE. However with a quick googling I already found that at least with RAVs it will push 14+ volts even when stationary in ready modes, so its not exactly that either.

The user @Dala has a lot of good graphs about this in his post history, check them out: Dala's Content - Toyota Owners Club - Toyota Forum

[TopGeek]

9 hours ago, CPN said:

That's fine, however, many of us have found that most of our cars do not have AGM batteries.

Then you don't need to use the AGM option that is available on most smart chargers.

[TopGeek]

5 hours ago, Stopeter44 said:

So Nico GB40, or equivalent, is fine ?

Logically yes. That unit is capable of delivering 1000 amps, whereas the current draw needed the raise the voltage sufficiently to enter 'Ready' mode would be unlikely to exceed 5 amps.

[TopGeek]

2 hours ago, Graham47 said:

@TopGeekDo you have evidence to back this up ?
What is the charging rate of the dc-dc converter ?

Not specifically but charging logic tells me that it is not possible to fully charge the Battery within an hour, during which the ICE will start and stop several times. All that can possibly achieve is to charge the Battery enough to offset the 'no start' situation.

[RickyC]

Sorry Brian, why are you correlating the 12v Battery change logic with ICE start and stop ?

[TopGeek]

4 minutes ago, RickyC said:

Sorry Brian, why are you correlating the 12v battery change logic with ICE start and stop ?

Not sure that I understand the question. Leaving the car standing in 'Ready' mode allows the ICE to charge the hybrid Battery, which then charges the 12-volt Battery. It is essenntially the state of charge of the 12-volt Battery that dtermines access to 'Ready' mode. It's all interrelated.

[RickyC]

I agree but I think that the charging process is totally idependent by how many time the ICE stays on or off.  I expect that an hour trip or an hour stand in Ready mode is quite equivalent for 12V Battery charge.  Probably one hour standby could be a little more efficiente because during drive you use more 12V powered components so part of the DC-DC generated power is immediately used and not sent to Battery, but I don't see any correlation between the ICE usage and Battery charge.