[Pynummoottil]

My 5 months old Jeep Compass Limited Plus' Stop & Start function stopped working 3 weeks ago. When I contacted the dealer, they informed me that certain conditions have to be fulfilled for it to work. (See attachment). However, since all those conditions seemed to have been met, I was not satisfied with their answer and so, I sent the vehicle back to the Jeep Service in Kottayam (Hyson) and their conclusion was that the battery charge is less than 50% and that the battery charge has to be over 70% for the Stop& Start to function. They felt that it maybe because the U-Connect Display is on all the time and that the display consumes a lot of power. I found this extremely hard to believe that a display can reduce the charge in a new battery. First of all I do not believe that a display system can draw so much power that it reduces the battery's charge. Moreover, the system has been put in there for use is it not?
I feel that the original battery supplied is faulty and that the dealer is just finding excuses to replace it which is something not uncommon in my experience in this country.
I just wanted the experienced BHPians comments on this, because I am a Surgeon by profession and not an Engineer. However, in spite of my not being an Engineer, common sense tells me that I am right.

[Mr.Boss]

Originally Posted by Pynummoottil

battery charge is less than 50% and that the battery charge has to be over 70% for the Stop& Start to function.

This sounds perfectly logical

BUT, not this.

Originally Posted by Pynummoottil

U-Connect Display is on all the time and that the display consumes a lot of power.

If the above is true, almost every compass on road should face the same issue.

- Is there any added accessory in your vehicle?
- If your usage is less, get the battery charged once (on bench) and check if the issue is getting sorted out. Later check if the battery holds the power (if not, check for any parasitic current drain or battery issue)

[Tarrodie]

They have given you a reason that not many will believe including the manufacturer itself.

The next step would be escalate directly to the company through an email with the same details and logic as above. Once you involve the company directly, it could be the same workshop you may have to go to in case it is the only one in the area, but there is a different set of people who will follow up on your issue, hopefully till resolution.

Also, there will be some pressure from the company to resolve the issue, so if it is indeed the battery that is at fault, there are high chances that you may get a replacement. But then they should check once again whether there is any other reason for battery drain.

[Indian2003]

It need not be a faulty battery. If the car is a Euro 6, you have a smart alternator that charges at low voltage and you have regenerative braking that dumps the load into the battery that stays at 80%. This to have space for the load that the brakes dump into the battery.

Dont let the battery drop to much below 50%. Recharge and you should be fine.

[Pynummoottil]

Thank you all for your replies. The fact is the battery charge has dropped below 50% without doing anything. Obviously, something is not working as it should.
There are no accessories.

[Jeroen]

Originally Posted by Indian2003

It need not be a faulty battery. If the car is a Euro 6, you have a smart alternator that charges at low voltage

That is not how a smart alternator works I think. Actually, smart alternators charge at a higher voltage compared to a regulator alternator, initially at least

What is the correlation between Euro 6 and a smart alternator?

Originally Posted by Indian2003

Dont let the battery drop to much below 50%. Recharge and you should be fine.

How does an average driver knows what the charge is of the battery? Unless you test it or put it on a charger that can actually tell you the load, it is going to remain unknown I think.

Jeroen

[Indian2003]

Originally Posted by Jeroen

That is not how a smart alternator works I think. Actually, smart alternators charge at a higher voltage compared to a regulator alternator, initially at least

What is the correlation between Euro 6 and a smart alternator?




How does an average driver knows what the charge is of the battery? Unless you test it or put it on a charger that can actually tell you the load, it is going to remain unknown I think.

Jeroen

Smart alternators were fitted from Euro 5 onwards together with automatic rear lights. This to save fuel. The average car owner will hardly notice this saving. The ECU regulates the charge as needed.

The smart alternator charges at between 12,8 and 13,7V while a conventional alternator charges at 14,4V. It charges when you are slowing down or braking.

Sure the average driver will not know the charge level of the battery but a trickle charger is needed for all cars to keep the battery in charge. Otherwise you will get a shop to do this for you. A simple battery monitor which you plug in sometimes will help a lot.

A car battery is not not a fit and forget component in a car. It has to be maintained.

[Jeroen]

Going a bit off topic, but as part of a stop & start thread it is good to understand smart alternators. As they have become an integral part of start/stop technology

Originally Posted by Indian2003

Smart alternators were fitted from Euro 5 onwards together with automatic rear lights. This to save fuel. The average car owner will hardly notice this saving. The ECU regulates the charge as needed.

Smart alternators were “mass” introduced from 2009 onwards. The technology in itself is not that new. There have been a few cars that were fitted with similar system since the mid 90s’. There is no specific or defined way on how a smart alternator works. All manufacturers have their own way. although the main principle are similar. For instance, depending on brand/make it could be the ECU, the BCM or the PCM controlling the charge. The biggest difference is how the charge is actually controlled.

Originally Posted by Indian2003

The smart alternator charges at between 12,8 and 13,7V while a conventional alternator charges at 14,4V. It charges when you are slowing down or braking.

This is what a conventional alternator looks like:



And this is what it looks like on a smart alternator:



Contrary what most of the internet will tell you, smart alternators do also charge at higher voltage than a conventional alternator. Actually voltage level can be very high to produce fast inrush of current into the battery to reduce start battery recovery time. So this is typically immediately after you have started your engine, or have not used your car for a long period of time and the battery has lost its charge.

Originally Posted by Indian2003

Sure the average driver will not know the charge level of the battery but a trickle charger is needed for all cars to keep the battery in charge.

A normally well maintained car should not need a trickle charger ever. If it does there is something wrong with it, or you are leaving it unused for too long period of time.

I have three classic cars that are always on a trickle charge. The reason is simple. these cars don’t get used much, especially during the winter months. So each has its own CTek charger. Actually, some of the more high end Ctek chargers are effectively “smart chargers”.

Next to my three classic cars, we also own and run three modern cars. All have start/stop system and none have ever been on a trickle charger.

Originally Posted by Indian2003

A car battery is not not a fit and forget component in a car. It has to be maintained.

I don’t agree. If your car battery is not properly charged either something is wrong, or you have not used your car often enough. It should not require any attention or maintenance. My classic cars are the exception (low usage).

Modern cars do put quite a bit of load on the battery, even when the engine and ignition is switched off. We have some other threads on this phenomena. Obviously, ambient temperature plays a significant role in how long a battery will hold a sufficient charge. But as long as the temperature doesn’t drop below 0oC any car should still start up after 6 weeks of no use easily.

I see you live in Oslo, maybe batteries require more attention especially during winter month. I spend a lot of my time in Sweden and I don’t see any Swedes hooking up their cars to trickle charger enmass during winter either.

Jeroen

[GTO]

Originally Posted by Pynummoottil

My 5 months old Jeep Compass Limited Plus' Stop & Start function stopped working 3 weeks ago.

On a lighter note = If everything else is working fine, I would consider this to be a blessing in disguise . And I hope the same malfunction happens in our new Superb! I hate the feature so much that I went to a tuner and got it disabled in my 5-Series. Sure, manufacturers provide a "disable" button, but most cars restart with the function enabled by default.

[saur95]

Originally Posted by Pynummoottil

My 5 months old Jeep Compass Limited Plus' Stop & Start function stopped working 3 weeks ago. However, since all those conditions seemed to have been met, I was not satisfied with their answer and so, I sent the vehicle back to the Jeep Service in Kottayam (Hyson) and their conclusion was that the battery charge is less than 50% and that the battery charge has to be over 70% for the Stop& Start to function.

I just wanted the experienced BHPians comments on this, because I am a Surgeon by profession and not an Engineer. However, in spite of my not being an Engineer, common sense tells me that I am right.

I'd say you're right on this not being related to the display, and if it is, it is entirely the manufacturer's fault, unless you've been using the display in Accessory mode for long periods (I trust you haven't).

Does the MID display any error message every time you come to a stop? If yes, then there is an issue with the components and not the activation conditions.

If not, when the dealer opens the vehicle diagnostics, it usually states as 'FALSE' if any condition is not met, just as it's mentioned in the leaflet you've attached. Ask the dealer to give you a screenshot/photo of the entire page (we can see the voltage etc as well). Ideally do this after a 10-20 minutes drive so most of the conditions are met.

With Toyota's S&S in the Indian Fortuner, other than battery SOC, the battery sensor calibration was an issue. Some electrical fault can cause the calibration to be lost. Try asking the service centre to recalibrate this sensor (can be done using the diagnostics software) and try again.

One item missing in this leaflet (which is universally applicable for S&S systems) is the difference in cabin and ambient temperature, or it is not defined properly. If the compressor has to run longer cycles to maintain cabin temperature (in Kerala heat!), the engine will be kept running. Try setting your AC at a higher temp, maybe 24-26 deg and fan speed at medium or low and drive around for maybe 20 minutes and see if it works then.

I have no personal experience with Jeep or other FCA vehicles and this is based on the Toyota system. Hope it helps.

[Nanolover]

Originally Posted by GTO

On a lighter note = If everything else is working fine, I would consider this to be a blessing in disguise . And I hope the same malfunction happens in our new Superb! I hate the feature so much that I went to a tuner and got it disabled in my 5-Series. Sure, manufacturers provide a "disable" button, but most cars restart with the function enabled by default.

Exactly as GTO sir has mentioned, consider it a blessing in disguise.

This stop/start puts a lot of load on the engine and transmission mounts due to constant rocking during start/stop. (No manufacturer explicitly mentions this ).The mounts end up getting replaced much faster ( manufacturer recommended intervals) . Better to disable this function permanently.

[funkykar]

Are you using your car enough? In recent weeks, was car unused for many days like a week or more around time issue started. I ask this as we are in a pandemic and car usage is quite less for most of us. Good chances are many of us faced drained battery or low charge battery in last 15 months more than once.

I don't know how superior is the alternator on the Compass. But if I were to relate it to my Linea which I used less in the last 6 weeks, but used 2-3 times a week at night, I ran into a low charge issue twice. My battery mechanic clearly told me everything is good on the car, the specific gravity or whatever its called is less, the charge is low. He also told me the reason is low usage and usage only at the night (as h/l will be on). HE said to drive your car in the day for say 50-60kms and try not to turn off much or get it to bench charged. I chose to go on a drive and since 3 weeks, no issues.

So until you check this issue with a fully charged battery, can't blame the car. Again, if your usage is low and happens to use at night, ensure your car is getting enough charge too.

Unless all questions on usage answered, cant conclude that the battery is bad either.

[KaurDiCar]

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[rahul_kej]

I think battery issue shouldn't be there in a 5 month old car. This feature is still working fine in my 6.5 year old XUV with stock battery. I hardly use this feature but still we want everything to run fine in our car specially a 5 month new car. Would suggest to get the battery fully charged once and try using this feature.

[Pynummoottil]

Thank you all for your replies.

During the week, the car is used only perhaps twice to do local shopping, but I do drive 115 km one way every Sunday to play golf. Moreover, as one of you mentioned this should never happen in a new vehicle.

Anyway, the dealers have agreed to change the battery after I had a (little bit of a tough) talk with them over the phone. Obviously, the original battery is defective and like most dealers (in my experience) they were trying to put the blame on the customer.

Once again thanks to all the BHPians who took the trouble to respond.