I don't mind the car shutting off at all, what I do mind is with AC on (68-70*) and the stereo going (solid bass and sub @ ~30 volume) the engine remains off for only maybe 5 seconds or so and then starts up again. That's fine for a stop sign with a few cars but surely not enough for a light. It's annoying that it turns off and then almost immediately turns back on.

I've tried disconnecting the module in the trunk behind the passenger side cover. That keeps the "ECO OFF" yellow light activated on my dash.
I also tried removing the ground from the ECO battery in the trunk and that also gives the same result of the yellow ECO OFF light on the dash.

The dash light is no good for me. I hate looking at that light. So I got to thinking what is causing the short duration? I turned the AC & Radio off and got a MUCH longer engine off time. So it must be measuring the drain on the battery. Two ways to get around that, either use a electrical work around OR get a bigger battery?

Has anyone tried hooking up a larger battery or spliced into the harness to trick the system? Looks like there's plenty of extra room for a bigger battery so I think I'll try that option first.

 

Digital,

You risking voiding your warranty if you install a battery that doesn't meet OEM specifications, or if you disconnect the small stop/start battery.

I'm not sure what you're trying to accomplish. Do you want your engine to remain off for a longer period of time and, therefore, save gas? Is that why you want to install a larger battery? Just because you found another battery with larger dimensions doesn't mean that it will outperform the OEM AGM battery; it may, in fact, be worse.

You do realize that while your engine is not running, your air conditioning compressor is also not running and, therefore, your interior will quickly get hot and humid in the Miami sun. I suspect that the system not only monitors battery drain but may also monitor interior temperature and humidity when the A/C is on to determine when to restart the engine.

If you're trying to turn off the stop/start system, so that your A/C keeps running and you're not annoyed by the short "stop" time, then simply press the ECO button on the dash, to the right of the NAV button.


You will have to press the ECO button to disable the STOP/START system every time you start your car. By default, STOP/START reverts to being ON whenever your start the car. I'm not sure, but your dealer may be able to reset the default to off.

I've noticed that the amount of pressure on the brake pedal affects stop/start. The lighter the pressure, the sooner the engine will restart.

If this was helpful, please press at the bottom right.

Stuart

 

Digital, I am not completely familiar with the ECO system as my car was not equipped with it. BUt, I can give you a little bit more information as it relates to the electrical side of things and what you will be looking for.

When it comes to batteries, size is not everything these days. So, just because the battery is physically bigger does not mean that it will last longer. What you really want to look for is the "capacity rating" of a battery. This is normally measured in amp-hours (or "AH"). The larger the number, the longer the battery can last with a given load on it. Most batteries that are meant to start the car have a rating of "80 AH" (or will last 80 hours with a 1 amp draw). In the case of your car, with the dash fan going (about a 25 amp draw assuming maximum fan speed) and the stereo going (assuming 10 amp draw), you have a 35 amp draw. This would mean that a normal size battery would last about 2 hours. If you have a little battery in there with say a 35 AH rating, it would in theory last 1 hour. This is the problem, that rating is based on a given current draw. If you go above that, the time the battery lasts is not proportional. What I mean by this is using an 80 AH battery, if you have a 10 amp draw, it will last about 8 hours, but if you have an 80 amp draw, it will only last about 45 minutes (or you are only getting 60 AH out of the battery).

Now, just to add confusion to this whole argument, you have to know what type of battery you are dealing with. I know this sounds silly, but follow me here. If you do some detailed looking, you will find that there are 3 basic types of batteries on the market: starting, deep cycle, and marine. A starting battery is just what the name implies, it is meant only for starting a vehicle. This type of battery is meant to remain at 100% charge all the time and only dip away from 100% charge for a few minutes. To pull a lot of power out of this type of battery and then charge it back up to 100% actually damages the battery and will result in a shorter lifespan of the battery.

You now have the deep cycle and marine batteries. These are very similar, so I am going to talk about them together. The only difference between the two is the internal structure where the marine battery is built with stronger internal plates to handle being knocked around and shaken to death. With a deep cycle/marine battery, these are actually meant to be deeply discharged (taken to near 0% capacity) and then charged right back up to 100%. To leave them at 100% charge results in a shortened life span. This is the style battery that if you are looking to increase the time the engine is off to say minutes for stop and go traffic you should be looking for.

As for how the ECO system operates, I think the first question you would need to answer is what is the trigger for the ECO computer to start the engine back up. This is a multi-answer thing. The obvious one is stepping on the gas pedal to make the car go. But, is it also triggered on the A/C temp rising XX degrees above the desired temp (where XX is a defined value)? Is it started based on the battery dropping to a certain voltage? Or is it ........? The owners manual might give you some clue to this.

If the system is triggering on a temp rise, there isn't much you can do about that other than turning the A/C system off and letting the inside of the car warm up.

If the system is triggering on battery voltage, then going with a larger AH battery should help extend this time. What you are counting on is the larger AH battery not having quite as much voltage drop for a given current draw. With an 80 AH starting battery, the general rule of thumb I use is 10 amps of draw results in a 0.1 VDC drop. If the ECO battery is say a 40 AH battery, you will most likely see something in the neighborhood of 0.2-0.3 VDC drop for the same 10 amp draw. You can possibly do a little bit of playing and connect a multimeter across the ECO battery and then turn on various loads in the car to see if the engine restarts at a specific voltage on the battery or if the voltage seems to be all over the place. You will need to be reading things out to 2 decimal places to get good info. You can also play with this some by having the same electrical loads going, but doing it one day where the morning temps are say 60F and then in the afternoon when the temps are hitting 90F. If you are seeing a dramatic difference in time, then there is a A/C temperature aspect to the ECO system.

 

An added note that if you do change to another battery, it must be one that the vent tube can be attached to as it is in an enclosed area, namely the trunk.

My issue is that the ECO mode has ceased working on my XJ and there are no warning lights. My tech says that he has seen that when one of the batteries, I think its the ECO Battery, falls below a certain charge ability. Mind you I,m not complaining, but thought it was interesting. I will be servicing the JX on May 10th and will have them check and remedy the issue.

 

Robert,
I'm pretty sure that the small "ECO" battery is available only from a Jaguar dealer. Any fault codes? Let us know what Pete A at JNP has to say about the cause and cost to repair. Do you use a battery maintainer, such as a CTEK?
Stuart

 

Jaguar referes to it as Intelligent Stop Start and IMO it is every bit of it. During the winter months it hardly goes into the ECO mode at all and during the summer when the AC is running the stop intervals can be short to supply the AC to keep the car cooled.
I have learned to work around the system by how I use the brake to shorten the stop time as needed.I have yet to to drive with the ECO Mode in the off position. In the summer I average 22.5 MPG, mostly in town with some highway, in the winter 19.5 MPG.
As far a the battery is concerned I will stay with the OEM for both, I just think this to be for the best. I did not know about the drain tube until I took my car in for a dead battery.
Two months after the repair I was in the trunk just checking out things when I notice this long black rubber tube not connected to anything. My gut feeling told me that it should be connected to something.
As this tube was right next to the battery I kept looking for the connection point. I finally found the connection port on the battery and connected it. I guess they forgot to connect
when the car was in service.
I later searched the web and found out that this was a vent tube used when a car battery was located in an enclosed area.
After 10 months and 4,700 miles I am still a satisfied customer and have no complaints. I am happy with the OEM tires and find the tires to be one of the quietest and smoothest riding tires on all surfaces in this size that I have driven on and I am talking, Michelin, Bridgestone and Continental.

 

YOu need to worry about the vent tube if you have a battery with the caps on the top. If you get a maintenance free battery, it is sealed and therefore the gases of concern cannot escape.

What you are worried about is the production of hydrogen gas and it building up in an enclosed area. If you have a battery with the caps so you can add water, the hydrogen can leak out and build up. If the battery is sealed, then there is no place for the gases to go other than inside the battery.

As for where these gases come from, this is easy. When you have water with a something in it (in this case, sulfuric acid), it causes the water to be conductive. When you pass a current through the water, it will use up some of the current and break down the water (made up of hydrogen and oxygen) into its separate gases. This concept is used in hospitals (to generate pure oxygen) and it is used on a submarine to keep the concentration of oxygen up. I am sure there are other places where it is used, but these are two common ones that I am aware of.

 

Unless I am missing something the OEM battery in my Jag appears to be sealed and has a vent tube.

 

Went in to the dealer today as a check engine light came on and wanted to get that diagnosed. Turned out to be a bad fuel evaporator sensor. So ordered that. The "pure gold" secondary battery is at 11 volts, resulting in the ECO mode not functioning. So no stop start or ECO warning indicators. They want over $300 for this modified motor cycle battery that you can buy for less than $80 and that is an AGM 12V/14ah/200cca battery with different posts. I am looking into an alternate battery from Interstate Batteries and modifying the cable ends to attach the battery. I'll keep the thread posted on how I resolve this. Jaguar only used this secondary battery for 2013 through 2015 cars and has now gone to a capacitor system and you cannot update to caps on the older cars. But, seriously $300+ for a Chinese Exide Battery is crazy.

 

"Sealed" or "maintenance free" lead acid batteries still need to be vented, as the gasses are still being produced and thus still need to escape somewhere. None of my Jag batteries have had removable caps. All have included the standard hole at the top edge in which to attach the vent tube to route the gasses out of the trunk.

 

My car shuts off for probably less than 10 seconds and starts again. Some times it's even less than thought. That's very annoying. I'd like to extend that to a longer time and I believe using a "larger" battery will allow that.

XJsss if you do go after market I'd like to see if you can get a beefier battery and comment on if it has extended the time you stay in ECO mode.

Thermo you have a '12 XJ right? Would you be willing to test what you laid out to see if it's voltage triggered?

Also I'd like to confirm that if you purposely kill the battery it won't go into Eco mode ? If you take off the ground it will throw the Eco off light.

 

Digital, my car is a 12 XJ, it was not offered with the ECO mode. So, I do not have the ability to test what I mention above. if there is someone in the DC area that would want to come over so we can play, then I would be willing to play and see what we can figure out.

 

If you have Intelligent Stop/Start and you're in ECO mode with your engine stopped and your goal is to keep the engine from restarting for as long as possible while you have the A/C set to AUTO or in manual mode (even though the A/C compressor is not running since the engine is stopped), press the recirculate air button AND HOLD IT until it displays Latched Recirculation On. Using "inside air" keeps the hot and humid outside air from entering the cabin, which minimizes the demand on the climate control system (one of the factors the "Intelligent" part of the stop/start system uses to determine when to restart the engine).

Per the Owner's Handbook, the engine will restart if one of the following occurs:
• Stop/Start is deactivated.
• The accelerator pedal is pressed.
• A shift paddle is used to select a gear.
• Reverse (R) is selected.
• Climate control system demand increases.
• The vehicle’s speed exceeds approximately1 km/h (0.5 mph).
• Battery charge becomes low.
• Brake vacuum has been reduced (e.g.using the brake pedal repeatedly with the engine off).

If this was helpful, please press .

 

It's south florida aka satans ball sack, the climate control is in great demand. I've thought about another method to get around it, where is the switch that activates it on the brake pedal and what else does it do?