2018 Jeep Compass Start Stop Not Working

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

Quote:

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.

Quote:

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.

Quote:

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.

Quote:

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

2018 Jeep Compass Start Stop Not Working

Source: https://www.team-bhp.com/forum/technical-stuff/235903-new-jeep-compass-engine-idling-stop-start-malfunction.html

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