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Why not build battery/charging/starter test electronics into new cars as p/o OBD II diagnostics?

Problems with batteries and starters would probably top the list of questions here. I wonder why auto manufacturers don’t put OBD II diagnostic electronics into new car to test these systems on-board. Like they do for the fuel tank evap system, O2 sensor, cat, EGR, etc.

It seems like all they’d have to do is monitor the battery voltage, everything-off current, starter terminals voltage and current during cranking, and a function to load test the battery. Then the car could tell the driver when the battery was past it’s prime, or the starter is about to give out.

The OBD II system is already there right? And it already tests stuff more complicated than the battery and starter. I can’t imagine the electronics package to test these two functions as part of the on-board diagnostics would cost more than $100.

Problems with batteries, wire connections and starters are easily diagnosed and repaired by someone with some experience with these things and with simple tools including a battery terminal wire brush tool, a wooden handle wire brush, a DMM and a battery load tester. The wire connections to do what you suggest could be a fairly large number including waterproof disconnects. The probable increased vehicle expense is likely not worth the effort in my view.

Replacement, formerly somewhat universal batteries and battery wires would need custom waterproof connections for each brand of vehicle until the repair world got fed up with the confusion as has happened to result in OBDII. Unless the design was done correctly, terminals for diagnosing wires would also be subject to corrosion.

I think that would run afoul of the Feds mandate regarding the OBDII system. Despite what many people think, the check engine light is not illuminated for random reasons.

Part of the regulations governing the OBD system is that the light is only illuminated for a fault that pertains to an emissions control device or a failure that can cause tailpipe or evaporative emissions to rise above 1.5 times the federal limit, or cause damage to a primary emissions control device.

There are already a number of fault codes that may be stored in memory that have nothing to do with emissions or driveability but they don’t turn on the engine light as a warning to the driver. For example your car may have a fault code stating it sees an open circuit in the washer pump circuit, but you’d never know it unless you had a factory level scan tool. Generic OBD tools and code readers are limited to powertrains, and at that only offer maybe half the info needed to accurately diagnose and repair a car.

One of the biggest problems with the OBDII system is that it’s really poor at determining fault. Probably half of the catalytic converters sold are because of some other component that’s faulty. A bad 02 sensor fault for example has dozens of other possible fixes other than replacing the 02 sensor. Bad gas, a dirty air filter or even a faulty engine component can trigger an erroneous fault. Adding to the system would only make it more unreliable than it is right now.

@missileman I disagree with you. IMO the problem is mechanics that are “really poor at determining fault.” If a mechanic automatically thinks a misfire code means bad plugs, he should be looking for another job. Yet I see this all the time.

I wouldn’t care how the warning was displayed, as a CEL, or some other dashboard display. But it would be helpful for me to know that – through the use of the ECM’s on-board battery load test – the battery (or starter motor via its test) was nearing the end of its useful life. Or that a phantom current draw has suddenly appeared, threatening to drain the battery. It would give me some warning to get the problem fixed, before I couldn’t start the car to get to work the next morning, or I was left stranded on the side of the road.

I added a voltage meter on my Corolla which helps somewhat. I can see the engine-off battery voltage and the engine-on charging voltage. And I can turn the headlights on when the engine is off to see how much the battery voltage drops. It gives me some indication of the battery situation at least. Maybe adding a voltage meter as standard equipment to the dashboard display would be a good start for the auto manufacturers.

@GeorgeSanJose here’s what would happen.

Some guy is perfectly happy with his car for 4 or 5 years. Suddenly the multifunction display tells him he needs a starter or battery.
He calls around to see how much that part costs.
Then he complains about the high cost of the part.
Then he has that part installed.
Then he feels cheated, because, in his eyes, there never was a problem.
Or . . . he questions the manufacturer’s integrity because the thing’s been starting fine, with no problems.

George they absolutely could put something into the ccockpit of cars to help the driver diagnose impending problems. The technology is certainly out there, new fighter jets have sensors that measure current draw for individual components, vibrations on components, etc. they will soon, but the auto industry is always lagging the airline industry. For instance B-52’s had ABS in the 50’s, we didn’t see that on cars until what? The 80’s? Of course the older version of ABS were all mechanical, rather expensive even by the aircraft standards. In my humble opinion, the auto manufacturer caters to the average driver, whatever age that is, and most people would not care to pay extra for any on board diagnosis widgets whatever the cost. And as was said earlier, any mechanic worth his salt can easily troubleshoot a starter,battery, alternator problem. For now, I guess you and me need to continue to buy 20 dollar digital voltmeters until the technology comes out.

The cost to engineer, jump through the government hoops for years, and put into production something like this would run into countless millions of dollars.

It would also add in yet another layer of complexity (WHAT! It’s going to cost me…) and lead to a CarMD scenario.
On-board display/CarMD says that X is bad, customer wants X replaced, and X doesn’t fix the problem so the car owner tells everyone in the county they were had by the shop.

To be honest, the majority of drivers would never pay attention to a voltmeter. Most are only concerned with the gas gauge and at times the speedometer. Even temperature gauges and oil pressure lamps are a nuisance to many… :slight_smile:

The average driver would not have any idea what the computer said. They would have to take it to a mechanic for an interpretation. They already do that now.

db4690…you are certainly entitled to your opinion but I think you are wrong. Why? Because the OBDII system is like your porch light going on to indicate that you have a problem somewhere in your house. Why have the OBDII system in the first place if you need a mechanic to determine the problem?

OBD 2 is around for standardization purposes.
In other words, to make diagnosis easier for me.
And it works.

OBD 2 is NOT around to give the car driver all the answers.

Who should diagnose your medical condition?
Or an MD?

OBD 2 is around for standardization purposes
OBD 2 is NOT around to give the car driver all the answers.

Right. I’ll also add that it’s there to alert drivers to issues they may not be able to tell even exist from the driver’s seat. Many are mandated by government such as emissions faults. Some are driveability issues that ultimately may impact the emissions or safety of the vehicle.

Convenience diagnostics wouldn’t appear to add a lot of cost but in fact do (relatively, when they seek to reduce some things by pennies that add up across huge volumes) and open them up to liability. “Ladies and gentlemen of the jury, the manufacturer created a false sense of security on the part of my client when their diagnostic process failed to identify a weak battery, leaving my client stranded and subsequently injured when he tried to fix the car on the side of the road”…Sad but true…

"The cost to engineer, jump through the government hoops for years, and put into production something like this would run into countless millions of dollars."

I agree and let me add to this. This translates to an additional dollars per vehicle. So here is the current scenario, there is a problem with the battery/starter/altenator. Dealer diagnostics ~$100.
Scenario with onboard diagnostics, vehicle cost ~$100 more, check engine light comes on, dealer diagnostics ~$100.

Wheres the benefit?

Ah. OBDII does monitor the charging system

P0560=System Voltage Malfunction
P0561=System Voltage Unstable
P0562=System Voltage Low
P0563=System Voltage High
P0620=Generator Contol Circuit Malfunction
P0621=Generator Lamp “L” Control Circuit Malfunction
P0622=Generator Field “F” Control Circuit Malfunction