I think this is what has happened to mine. My car doesn't have a working Eco mode and the wiring all looks hooked up to the second battery. In the service history I see that a new battery was fitted about 9 months ago so presumably the folks that did this also didn't sync. Don't get me wrong, I don't want Eco (who buys a 500bhp car and cares about gas mileage?) but I would like to understand why it is not functional.

- Is there a way to check *why* Eco might not be working? Presumably a dealer diagnostic tool would be required
- How *do* you sync the battery with the module? I did this on my BMWs using a diagnostic tool, I can't see anything similar available for the Jaguar so again go to someone with the tool available?
- Now that my battery is 9 months old is it possible / advisable to sync it anyway?

-- Chris

 

The tech at the dealer uses a laptop to sync the battery, I presume with a connection to the OBD port. No harm to do it after 9 months, but the you would have to disconnect the appropriate wire to disable the ECO start.

 

OK thanks. I might take it in for a diagnostic first. If that shows that the only reason Eco isn't working is the lack of a battery sync I will just forget about it as I'm in no need of that feature. If I do end up with it enabled it's not the end of the world as my car is in Dynamic virtually the whole time and my understanding is that my model disables Eco when in that mode.

Thanks again

 

I’m assuming they replaced the main battery only, and not the ECO battery too? Try measuring the voltage on the ECO battery (under trunk liner, right rear corner.)

 

Good idea, I'll get the meter on it when I get home, thanks. My understanding is that the secondary battery is isolated from the main one when it's not being used or charged so the reading should be real I guess.

 

Would probably be best to disconnect one lead of the battery before measuring. I know that FETs (transistors) are used to isolate the ECO battery + car electronics from the main battery + starter during starting. Don't know what state it's in otherwise.

 

The iCarsoft LR V2.0 supposedly resets the BMS, see here: https://www.ebay.com/itm/iCarsoft-LR...aa4060796598da

I have one and tried it on my F-Type (which has never had a single battery or electrical problem) but it didn't work, kept saying "process failed" or similar. Maybe because I have disconnected the secondary battery?

Anyway it's a damn good diagnostic tool for an F-Type and you really need such a tool.

 

That does look pretty neat actually so I just bought one. I'm sure this won't be the only time I need to poke around like this, thanks for the heads up

 

I left second 2nd battery failure as is. It only stopped the start/stop function. When I had the first repaired I took some good natured heat for doing it. I don't miss start stop at all!

 

I'm with you Sir. I just have a couple of months where the seller will need to pay for anything that was advertised as working. I don't want stop/start at all, but I do want to know if something else is fubar in the electrical system. If I can be sure that the problem is simply the second battery or lack of a battery sync then I'm cool to leave it alone at that point, I just don't want to be dumb and find out that I've got a failing alternator, BMS or some other expensive problem when it's too late and is my cost to wear.

 

OK so I got my iCarSoft today and it does indeed offer the BMS sync option, for both the main battery and the Eco one. I tried the sync but it didn't fix the problem. However the ODB2 section of the tool allows you to measure the voltage of the main battery (but not the second one as that's non-standard for ODB2 AFAIK) and I was getting a reading of 11.4v when parked and nothing operating which unless I'm sorely mistaken is badly low. I'm surprised the car isn't throwing more problems than just a stop / start failure. I still haven't gotten around to measuring the second battery voltage as my electronics toolbox is inconveniently buried for now but will in the next few days as I'd also like to verify that 11.4 reading with the battery isolated from the rest of the car.

 

Yep, 11.4v is way low and pretty much confirms the battery is knackered.
It should read 12.5v - 12.7v straight after a drive or charge up, and then after a while the BMS will put it in rest mode and drop it to around 12.3v.