Battery.

[JasonO]

They charged it to 90%. Also after a long drive it was at 64%, explain that.

I already have, but let me try again.

They put it on an external charger. That charger is not governed by the system so it can charge over the 80% limit of the BMW battery registration. The BMW charger in the car doesn’t necessarily charge at full current and will allow some discharge within reason. The battery is taking charge, the car isn’t charging it to your liking.

My own anecdote. My battery from time to time if I turn the car off at the wrong time not have a high enough capacity for my signal generator to recognize the startup signal so it will fail to turn on my amplifier. This happens once out of thirty times at worst. This points to the charging system is controlling charge current and will only get aggressive on charging at lower battery voltage levels. You don’t see me shitting bricks over this and I’m an engineer involved with lead acid battery systems.

Like I said, IMO, you only deserve a new battery because they promised you one, not from the metrics as they are shit metrics. You absolutely may have a battery with less life, but I wouldn’t trust the data points you are giving to make that call. The system is meant to trend and alarm in absolutely concerning conditions, not make a snapshot based decision about marginal losses.

Sponsored

 

[John8]

I already have, but let me try again.

They put it on an external charger. That charger is not governed by the system so it can charge over the 80% limit of the BMW battery registration. The BMW charger in the car doesn’t necessarily charge at full current and will allow some discharge within reason. The battery is taking charge, the car isn’t charging it to your liking.

My own anecdote. My battery from time to time if I turn the car off at the wrong time not have a high enough capacity for my signal generator to recognize the startup signal so it will fail to turn on my amplifier. This happens once out of thirty times at worst. This points to the charging system is controlling charge current and will only get aggressive on charging at lower battery voltage levels. You don’t see me shitting bricks over this and I’m an engineer involved with lead acid battery systems.

Like I said, IMO, you only deserve a new battery because they promised you one, not from the metrics as they are shit metrics. You absolutely may have a battery with less life, but I wouldn’t trust the data points you are giving to make that call. The system is meant to trend and alarm in absolutely concerning conditions, not make a snapshot based decision about marginal losses.

Ok, the norm is 80% charge as set by the alternator system and electronics involved. If the car sits, say for 6 months or a year (we some times go out of country to do work abroad (I do medical work and do visual documentation), how do you trickle charge it, since this will often bring it to or near 100%, since the trickle charger doesn't have the programming the car does?

 

[Grendel-13]

Get one of the BMW smart chargers for the car. They are meant to charge the car for longer periods of time I doesn't just do a trickle charge which is bad for long term storage.

https://www.bmwblog.com/2016/01/28/bmws-new-ctek-battery-charger/

 

[JasonO]

You can still trickle charge it. The battery maintenance system of the car will just hold off or reduce charging until it feels it needs to.

I’m intimately familiar with a similar stationary system (not the BMW one) and it wants to hold the battery around 70% (for extended life) and will not charge above 80%. It will not commence charging until 60%. There are some caveats with it, but that is the gist of it. If I had to guess from what I’ve read of the BMW system, as I had similar concerns that you had, it wants to hold the battery at 70-80% but does not charge the system until it is somewhat lower than that.

In general, light discharges and recharges are better for AGM product than deep discharges or constant charges.

 

[Tkoch86]

Mine is doing that, while locked...they did some recall update on the rear camera and I think screwed up the update. When one is done it updates all systems. They didn’t seem to know what they were doing... the temp and fuel and the tach numbers. Also the hazard button. Been on for like 20 minutes now.

 

[akasonny]

Battery charging, condition at time of purchase and warranty has been discussed a few times here. I have posted that I got my Nitro, and was told that the battery had been replaced, because after I drove it, they tried to start it (days later and needing to move it) and it wouldn't start. After I purchased the Supra, I asked for confirmation that it had the new battery. They then said it had been charged, and that no battery had been replaced. A head person in service and a sales person had told me it had been replaced.

So I have an app now, for about 5 days, Bimmerlink, that shows the charge state of the battery. It has been down to 64% after driving, which concerned me because I have been driving it and not sitting with the battery on but with the engine off. Then I took a long drive, 3.5 hours and it stood at 80%, why not at 100%? I then got a charger and left it on slow charge until the charger showed "Full", at capacity. That capacity is 89%, not 100%. Bimmerlink shows the battery as a 105Ah battery, which it is (it is marked on the battery and with BMW, on the battery).

I work with a number of different types of batteries and this indicates to me, that the battery will not take a full charge and due to being run down to or near zero, at the dealership, has been damaged.

Does anyone have current state of charge on their battery using an app, that show what normal charge state it is in? Thanks for any info.

Others may want to confirm but I've been told the battery (for some odd reason) is considered fully charged at 80%...by design.

Where in Bimmerlcode do you see the charge state of the battery?

 

[John8]

Others may want to confirm but I've been told the battery (for some odd reason) is considered fully charged at 80%...by design.

Where in Bimmerlcode do you see the charge state of the battery?

Yes, after finding this out myself, I called a few BMW dealerships. One said they had never heard of that and of course, it should be charged to 100%. Another large BMW dealership in Calif. (manager) said, it was correct, they only charge to 80%. He had asked one of the top people why, when they were visited by BMW, and they would not tell him! But he confirmed that the batteries only are charged to 80%. Mine charges up to 82% and that is it.

 

[akasonny]

My short interpretation as someone involved heavily in lead acid storage as a career. Your battery is likely fine. It has had some factors that will shorten it’s life based on what you have said, but without real testing (expensive), it could be several months or a year or more lost. The monitoring software cannot truly say. Also, since conditions have improved for the battery (it now gets charged), degradation will slow down.

With that said, if they told me they replaced the battery as a condition of sale and admitted later that they did not, I’d make a scene and contact Toyota NA even if they replaced the battery at that point.

The long boring part as to the why monitoring systems suck at high resolution data:

SoC on lead acid batteries is not exact with the data available to Bimmerlink. I think it could be terribly off which is why the system flags are set conservatively and this data has to be pulled with diagnostic tools. It needs interpretation and understanding of limitations.

The BMW monitoring system pulls data from the negative terminal of the battery. It is getting post temp, voltage, and current. It is monitoring these over time and calculating snapshots based off this data through a set of formulas.

For lead acid product, cell voltage at rest or under stable float currents without power draw can be a reliable indicator of the state of charge. SoC and capacity are not the same. You could have shit capacity left, but high voltage as your battery is now capable of delivery all of that shit capacity. The flip side is you could have high capacity and low voltage, so you can only deliver part of the capacity. State of charge is relative to actual, not rated capacity.

The issues with this system are: you are measuring multiple cells (6) at once, so low cell voltages can be masked by high cell voltages, float voltage is not stable, power draw over the battery reduces accuracy, and voltage does not equal capacity. While there is a lot of data, it is not all good data.

Unless the internal flags get set for a bad battery, whatever SoC is shown will not be enough for warranty replacement. Batteries SoC varies during service, actual (not rated) capacity, temps, time of charge, and age.

Just some info below on what a real capacity test does:

To properly provide actual capacity of a battery per IEEE 1188, (VRLA product) the battery is taken offline and must undergo a controlled discharge using the battery specifications to the battery’s end voltage. There are bunch of other requirements as well, but that is the gist of a valid test to comply with minimum maintenance and regulatory standards. Once the test is complete, you have the capacity of the battery that is valid for warranty and maintenance purposes. The battery is then recharged and put back online.

The Supra uses AGM batteries.

 

[akasonny]

Yes, after finding this out myself, I called a few BMW dealerships. One said they had never heard of that and of course, it should be charged to 100%. Another large BMW dealership in Calif. (manager) said, it was correct, they only charge to 80%. He had asked one of the top people why, when they were visited by BMW, and they would not tell him! But he confirmed that the batteries only are charged to 80%. Mine charges up to 82% and that is it.

Mine was dead on the dealer's showroom...much to the chagrin of the embarrassed salesman. They couldn't release the car to me saying that BMW has to reprogram all ECUs...not just a charge. I was told they'd replace the battery. They didn't. They simply recharged, re-calibrated and delivered the car to my front door 2 days later. I've had considerable concerns over this issue...and documented the situation.

I haven't had any noticeable problems since though I suspect that condition shortened the battery's lifespan. I was careful to buy a charger with a specific AGM charge (I believe long-term use of a non-AGM charger is a bad idea).

 

[XtremeMaC]

I don't know much about the AGM batteries, but Lithium Ion / Nickel / Po.. etc. batteries which are commonly found in everyday devices (laptop, phone, etc.) always advised against fully charging. Most laptops do say though, if you keep it plugged in all the time, let the battery charge up to 80% (controlled via software), but seeing how phones are frequently replaced and charged every night, they're a different story than car batteries, but chemically they're similar enough to say don't let charge go down below 20% and charge over 80%...
yet again, software controlled devices show that it's 100% charged where in fact they're 80% to improve health/longevity.. Sounds like BMW is using this software control idea as well...

 

[puzzled]

Has anyone found a good way to wire the battery tender from under the trunk? I don't drive my Supra all that much and have been routing the cord from under the engine bay into the charge posts in the front using alligator clips. This way I can keep the hood closed completely and enjoy the beautiful car while parked in the garage.

Since I will be disconnecting the battery temporarily to install paddles, I would like to wire the umbilical cord at the same time directly on the battery terminals, and drop the umbilical cord under the trunk so that I can plug it from under the car without opening anything.

My car will never see snow nor rain so not really worried about water although I will take precautions to place in a dry location.

 

[XtremeMaC]

Since I will be disconnecting the battery temporarily to install paddles.

slightly off topic: There are several people in the forum with depleted batteries getting error messages... I don't remember right now if that's because ECU is getting lower voltage than ideal or if for some reason ECU doesn't like disconnects or cannot recognize new battery or whatever. You gotta be able to disconnect the battery. Chances are I'm misreading this whole thing

 

[John8]

Mine was dead on the dealer's showroom...much to the chagrin of the embarrassed salesman. They couldn't release the car to me saying that BMW has to reprogram all ECUs...not just a charge. I was told they'd replace the battery. They didn't. They simply recharged, re-calibrated and delivered the car to my front door 2 days later. I've had considerable concerns over this issue...and documented the situation.

I haven't had any noticeable problems since though I suspect that condition shortened the battery's lifespan. I was careful to buy a charger with a specific AGM charge (I believe long-term use of a non-AGM charger is a bad idea).

Mine was dead on the showroom floor, the day before I came back to see it again. They told me they replaced the battery. They lied, I found out later. I asked for the paper work and they admitted the recharged it but said, "it is under warranty". I hate lying and I lost most all confidence in them. This is main dealer in Tucson.

 

[puzzled]

I read another thread about not connecting the tender directly to the battery so scratch my idea. I wish there was a safe way to plug the car in from under the car without needing to open the hood each time.

As for unplugging and plugging the battery, I think if you do it in one shot on a charged battery you'll be fine. It's usually when there's insufficient power and people open doors or what not, the fluctuation in current causes the errors.

 

[akasonny]

Mine was dead on the showroom floor, the day before I came back to see it again. They told me they replaced the battery. They lied, I found out later. I asked for the paper work and they admitted the recharged it but said, "it is under warranty". I hate lying and I lost most all confidence in them. This is main dealer in Tucson.

This happened to me too. I live in Tucson but bought the car in Phoenix. That dealership promised a new battery but, later, said they recharged it. Argh!

Sponsored