[ninjag]

You can check the voltage on your dash (if you've an x250 classic, not sure about FL though) by putting the car into into engineering mode.

Oh, what's this engineering mode?

 

[Gav]

See here;
https://www.jaginfo.org/showthread.php?4310-Secret-menu-jaguar-XF

 

[ninjag]

See here;
https://www.jaginfo.org/showthread.php?4310-Secret-menu-jaguar-XF

Cool, thanks!

 

[Rooster5555]

Hi lm reading here about the small battery which does start stop is this correct as other posts lve read say it doesn't also l have just replace my main battery does the small one charge from the main or should l charge the small one while fitted on the car like you do with main battery many thanks

 

[OzXFR]

Hi lm reading here about the small battery which does start stop is this correct as other posts lve read say it doesn't also l have just replace my main battery does the small one charge from the main or should l charge the small one while fitted on the car like you do with main battery many thanks

The small battery doesn't power the starter motor that is still dome by the main battery.
All the small battery does is run the ancillaries (lights, HVAC, infotainment etc) for the second or so that it takes to restart the car from a stop/start initiated stop.
AFAIK the small battery is not charged from/by the main battery but it is charged (along with the main battery) when you connect a battery tender to the usual/recommended charging points.
If not then it is easy enough to charge by connecting a tender directly to it's positive and negative terminals.
As an aside I have had the small battery disconnected in my F-Type for the last 3.5 years, and completely removed from the car for the last month or so, and three days ago I tried a little experiment - I connected my battery tender to it to check it's state and see if it would charge up again fully/properly, and it charged up fully in a couple of hours no worries.

 

[bmcl26]

thanks. my stop start is not working- sounds like this could be worth a try.

It is actually the Large battery that controls the Eco Stop/Start. I have a2013 2.2d Portfolio and the Eco Stop/Star stopped working. Having read a few forums I suspected the batteries may be suspect and as I only had an old charger which is no use for the AGM batteries fitted to vehicles with Stp/Start I bought myself a Ctek MSX5 Charger. As I suspected it was the small battery causing the problem (as the car was starting fine and everything else was working OK) I connected the Ctek to the smaller one first. After only a few minutes the lights reached 4 (which indicated the battery is not fully charged but serviceable) I then connected it to the main battery after only about one minute the fault light on the Ctek started flashing, I reset this a couple of times with the same result. Reading the charger manual this advised that I was one of three things 1) The battery was heavily sulphated, 2) The battery could not be charged) or 3) the battery could not hold a charge and advised that in all these instances it needed replacing. I obtained a replacement may battery (Exide) from Tayna Batteries for £136 delivered next day. I replaced the battery reset the BMS with an iCarsoft LR2 (although I believe that if the new battery is fully charged the BMS will self reset after a couple of days. Only other thing needing reset was the electric windows. I took the car for a drive and hey presto Eco Stop/Start kicked in at the traffic lights half a mile from home and has worked perfectly ever since. Since the lockdown and the fact that the car is only used once a week now for shopping, I purchased the CTek Comfort Connector and Indicator (just over £20) This comes is now connected (fused) directly o the Positive Post of the main battery and the negative to a nearby bolt on the chassis. The small indicator is fitted to the sidewall of the boot (template provided for cutting the hole and I can now see at a glance the battery condition Green LED + Fully Charged, Amber LED = Charge Soon & Red LED = Charge immediately. When I need to it is now simply a case of plugging in the charger to the adapter on the indicator and let it do its own thing. If required it can be left plugged in and will monitor and trickle charge the batteries to maintain it in peak condition.

 

[brake-buster]

great explanation ,

i replaced my small battery last month ( 2015 2.2d sportbrake ) , but still no stop/start and everything is indicating the main battery , i see there are Exide 850 , 900 and 950 output versions, i may as well go for the 950 for the few extra quid i suppose

BB

 

[OBC John]

After my recent experience with battery changing (I replaced both the main and auxiliary batteries) I'm convinced that you do need to "tell" the car about it. The stop-start still didn't work until it went in for its service. I mentioned it and all was well when I picked it up.
The iCarsoft LR II can reset the battery module. I have one but didn't realise until I read about on here. Doh!

 

[Gav]

I hear you John, but think by resetting it just tells the bms - you’ve got a new battery so therefore no need to do your battery run down testing capacity, but in my experience the bms will sort itself out.
ive had the car on trickle and the ss kicked in a few days after been sat around.

 

[Fred00]

Anyone who needs a new battery and gets a quote of £300 by a dealer to fit and replace it should have a read below.

The official battery sold to you by Jaguar will cost approximately £191 with the rest of the quote for fitting.

The auxiliary battery on mine (2012 facelift) is the small secondary battery in the boot just along from the main large battery. Its held in place with a covering bracket with 2 size 10 bolts and then the standard battery post bolts which are also size 10. It takes about 5 mins to remove this battery.....

From my research I found that the battery is an Exide EK151 model. This tends to retail from around 50-60 pounds on the internet but I found it online here :-
You searched for 3a57dabab0ae60af7fd0f75b4cd69ba2 - BBL Batteries

I phoned them up and had one delivered next day for the total amount of £40.20
I was surprised to find that when opening the package it was exactly the same as the official Jaguar part, including the stickers. I have attached a picture of both the original and new batteries side by side. The new one has the label EK151 on it.

I fitted the battery and almost immediately the stop/start began to work. No additional work was needed at all.

I hope this helps anyone avoid being ripped off by the dealer for this part.
View attachment 154626

I hope this helps anyone avoid being ripped off by the dealer for this part.

Hey Chris did you have to program the battery

 

[JohnnyJaguar]

It's one of the commonest misconceptions about our cars. The dealers all tell you the same thing.
The truth is that they can tell the system the size of the battery from the outset, but over the course of a few days the system will automatically let the battery drain down and relearn the capacity.

It's something which the system does on a regular basis anyway as batteries (as we know) degrade over time.

hi Phil, thanks for this post. I’m asking for dealer quotes and I’m pretty shocked! My worry is the reports of all manner of things going wrong when not ‘programming in’ the new secondary battery. Was there a specific procedure you followed to ensure a trouble free removal of old and install of the new battery? It turns out my alternator seems shot so I’ll need a pro garage to do that, but I will try to save on the bill by doing the battery myself.

 

[MalcXFR]

I believe the problems can occur when disconnecting the main battery not the small secondary one.