[PearlJam]

Modern cars today are equipped with all kinds of sensors. You name the potential problem, and there's a sensor for it. These in turn are connected to the dashboard display to give visual feedback to the driver. For example, my swift dzire has indicators for power steering problems, ECU, brakes, oil. There's also an indicator for battery charging, which I'll come to later.

After servicing my car last August, I was driving my car with no issues. Life was monotonously predictable and good, when suddenly one morning last week, two indicators continued to be lit up even after starting:



According to the owner's manual, The left one idicated "service reminder" (how considerate!), and the right one was "Water in the fuel filter, that needs to be drained". However, there was absolutely no problem in starting the car. Switching off and starting again would always fix the indicators.

Since I was busy that week, I ignored the problem. Every morning was the same result - the two indicators would light up, and stopping and starting again would fix it. Yesterday morning was no different. Since I had to stop somewhere for some work, I switched off. When I came back to my car to start, it would keep cranking and refused to start. There was no noticeable "struggle" during the cranking. Waited for some time and started again, and I was lucky to get it started on the fourth try. And no indicator lights were lit up, giving an impression of absolute normalcy (I felt that this was my car's way of getting back at me for ignoring her!).

Went immediately to the service center and explained the problem. The SA immediately analyzed it as a battery problem. He connected the battery diagnostics tool, which rated my battery health as a poor 3/10 (that delivered the harsh and expensive verdict: Replace battery). He then connected the SDT and cleared the error codes.

When I asked him why some random indicators lit up, he said that all sensors will start to malfunction when power is not optimum. Got the battery replaced, and everything got fixed. Happy but expensive ending!

However, the big question now is: Why can't cars have a "battery problem" (or replace battery) indicator? If the battery tool could accurately guage the battery health, why not embed this logic in the ECU itself? This is one issue that each and every owner will be facing once every 2.5 to 3 years of ownership. The current battery indicator just indicates charging problems, which I'm sure is a rarity. Given that there are indicators for all kinds of rare problems, why not an indicator for this common problem? In addition, the two indicators above had no relation to the actual issue.

I'm sure why none of the cars sold today here this indicator (please correct me if I'm wrong). Thoughts on this appreciated!

[CrackedHead]

Is it possible to distinguish a discharged battery(one that can be revived) from a dead battery (one that needs to be replaced). My understanding is that a discharged battery must first be charged before it is checked.

Where did you replace the battery - they are quite overpriced at the A.S.S and much cheaper at the battery dealers.

[sgiitk]

I have a feeling that this may have to do something with the following:

1. Lower cost since a battery status meter costs more than a pilot light.
2. With an Alternator having an electronic regulator the meter will not be much use. The light is equipped to sow if there is no excitation, that is all.

[PearlJam]

Mod Note : Please use the EDIT or MULTI-QUOTE buttons instead of typing one post after another!

Originally Posted by CrackedHead

Is it possible to distinguish a discharged battery(one that can be revived) from a dead battery (one that needs to be replaced). My understanding is that a discharged battery must first be charged before it is checked.

I definately feel that it is possible to distinguish the two cases. From what I observed, the battery diagnostics tool works something like this:

1. Switch off car, and connect the two wires to the battery.
2. Start the tool. Tool will tell you what to do next.
3. Tool says "Start the car". So you start the car.
4. Tool says "Switch on head lights now". So you switch on the headlights
5. Tool says "Raise to 3000RPM". So you do that.
6. After a few more instructions, tool gives a printout.

The tool basically senses the load on the battery during the various operations.

Given that the charging system is working alright (as inferred from the absense of the battery indicator), shouldn't it be possible to embed the above kind of logic directly in the ECU?

Originally Posted by CrackedHead

Where did you replace the battery - they are quite overpriced at the A.S.S and much cheaper at the battery dealers.

Yes, the dealer was expensive. So got a new Exide matrix with 5 years warranty (2.5 years full replacement, 2.5 years of depreciated discount for replacement) from a place called Karuna Auto electric near Sagar Automobiles. Costed me 9300 minus 800 for exchange = 8500/-.

Originally Posted by sgiitk

2. With an Alternator having an electronic regulator the meter will not be much use. The light is equipped to sow if there is no excitation, that is all.

I'm not sure I understand. Which "light", "meter", and "excitation" are you referring to?

Note that the battery dealer did open up the battery and found two of the six cells to be dead, basically confirming the battery diagnostics tool output.

[Aroy]

Originally Posted by PearlJam

I definately feel that it is possible to distinguish the two cases. From what I observed, the battery diagnostics tool works something like this:

1. Switch off car, and connect the two wires to the battery.
2. Start the tool. Tool will tell you what to do next.
3. Tool says "Start the car". So you start the car.
4. Tool says "Switch on head lights now". So you switch on the headlights
5. Tool says "Raise to 3000RPM". So you do that.
6. After a few more instructions, tool gives a printout.

The tool basically senses the load on the battery during the various operations.

Given that the charging system is working alright (as inferred from the absense of the battery indicator), shouldn't it be possible to embed the above kind of logic directly in the ECU?

Yes, the dealer was expensive. So got a new Exide matrix with 5 years warranty (2.5 years full replacement, 2.5 years of depreciated discount for replacement) from a place called Karuna Auto electric near Sagar Automobiles. Costed me 9300 minus 800 for exchange = 8500/-.

What the tool was doing is to gauge the battery charge holding capacity, by analysing the voltage at various loads. If you have a load verses voltage graph from the manufacturer even you can gauge the battery health - the further away from the line the worse it is.

As noted in some other thread, once the voltage drops below a threshold, electronics starts misbehaving, hence the first sign of a bad battery would be random lights lighting up.

By the way, did the battery really cost Rs.9300/ new? Here in Delhi a battery for my Esteem costs between 2200 and 3500 (Exide, Amaron, Base etc). 9 k is in the realm of 150AH Inverter grade battery not a 50-60AH Automotive one.

[mayankjha1806]

These days batteries themselves have indicators to let the owner know if its getting bad and take preventive action, although i agree its not user friendly and one needs to open the hood occasionally. I have found these indicators to be fairly accurate and when the battery went bad the indicators were complaining for sometime, its just that i was ignoring them.

A battery meter or indicator would mean even more electronics and chance of them going bad or reporting false cases of battery problem when its just a loose connection that might be causing it.

[sgiitk]

Originally Posted by PearlJam

I'm not sure I understand. Which "light", "meter", and "excitation" are you referring to?

Light : Warning light on the dash. Also called the i%%%%t light.
Meter : battery condition meter or Voltmeter
Excitation: Current fed to the Alternator rotor to get it going.

[PearlJam]

Originally Posted by Aroy

What the tool was doing is to gauge the battery charge holding capacity, by analysing the voltage at various loads.

Wouldn't that be a simple thing to implement in the ECU? Or is there a limitation in doing that within the ECU?

Originally Posted by Aroy

By the way, did the battery really cost Rs.9300/ new? Here in Delhi a battery for my Esteem costs between 2200 and 3500 (Exide, Amaron, Base etc). 9 k is in the realm of 150AH Inverter grade battery not a 50-60AH Automotive one.

Yes, it cost me 9300-800(for old)=8500/-. It is a DIN65(LH). Look at http://www.exidedealer.co.in/pricing-2feb2011.pdf. If you opt for a 3 year warranty (1.5 year replacement + 1.5 year depreciated discount) then it comes to around 7500/-.

Originally Posted by mayankjha1806

These days batteries themselves have indicators to let the owner know if its getting bad and take preventive action, although i agree its not user friendly and one needs to open the hood occasionally. I have found these indicators to be fairly accurate and when the battery went bad the indicators were complaining for sometime, its just that i was ignoring them.

My OE battery had no indicator. But the battery in one of my friend's Maruti 800 had this indicator showing green, even though the battery was almost dead. I guess the indicator doesn't take load into account. So I'm not sure of it's reliability.

Originally Posted by mayankjha1806

A battery meter or indicator would mean even more electronics and chance of them going bad or reporting false cases of battery problem when its just a loose connection that might be causing it.

Well, let's not get into that area, because in that case anything can go loose anywhere, right? Why have any sensors at all

[esteem_lover]

I guess since the battery is very much 'up front' and easily accessible for testing and fixing and also sometimes needs regular checks, it is considered not worthy of a place in the instrument panel.

[SmartCat]

Dead batteries are probably responsible for majority of breakdowns in modern cars. Get rid of this problem and you will have a car with higher reliability. Measuring battery charge must be technically feasible - you have all the hybrids & EV cars with gauges to measure how much battery life is left.

Else, manufacturers should put a second battery in the car and ignition system should alternate between the two batteries every time you start the car. If one battery completely conks out, the system should automatically switch to the other battery and let the user know that one battery is dead.

If a college gives such a project to even mechanical/automobile engineering students, I'm pretty sure a simple cost-effective solution will come up.

[1100D]

The potential across the terminals can be used as a start point.
If the battery is not able to provide sufficient starting amps, thats another indicator.
Coupled with the full load voltage provided by the alternator in recent times. The systems can be made to understand that a bettery is getting bad, progressively.

One more thing, the alternator indicator can be made more useful. It only indicates when an alternator has failed completely, but what if its potential across its terminals is lower than normal (at any given load, considering the potential drop as well).

[sgiitk]

@smartcat; I like the idea of a second battery, but that too may run out at the same time as the primary battery.

Most modern batteries have a pretty flat discharge curve. In other words there is very little change in the voltage from say 90% charge to 20% charge. We all know how unreliable the battery indicators on our mobiles are. Also, conventional Pb-Acid and (near) zero maintenance ones have slightly different working voltages. Furthermore, this tends to drop as the temperature goes up.

[Guna]

Originally Posted by PearlJam

However, the big question now is: Why can't cars have a "battery problem" (or replace battery) indicator?

Isn't the 'battery malfunction' indicator already present? The one inside the speedometer dial?

[PearlJam]

Originally Posted by smartcat

Dead batteries are probably responsible for majority of breakdowns in modern cars. Get rid of this problem and you will have a car with higher reliability. If a college gives such a project to even mechanical/automobile engineering students, I'm pretty sure a simple cost-effective solution will come up.

Exactly. I've seen countless situations (and faced a few within the family myself) where people just get stranded due to a dead battery. And surprisingly, you would absolutely not have had any indications of this. Headlights and horn, usually the first indicators of a weak battery in older cars, would have continued to work perfectly till yesterday in these modern cars!

Originally Posted by 1100D

The potential across the terminals can be used as a start point....

Yes, we need some logic like that, and I'm sure it's not rocket science to come up with something!

Originally Posted by Guna

Isn't the 'battery malfunction' indicator already present? The one inside the speedometer dial?

No, as I mentioned in my original post, that (misleading) indicator is just for reporting problems with the alternator charging.

[pganapathy]

I think the main problem with a battery malfunction indicator is that there needs to be the following installed in the car.

A voltmeter for reading the battery.

Without this, it is impossible to tell if the battery is dying or not. At present this does not exist, though to be fair it is not very difficult or expensive to fix. Though this leads to the inevitable issue of how cars are becoming more electronic (more potential problems to fix when something else breaks down).