Hi Folks,

Looking for advice please, ie. Do's, don'ts, caution, regarding the replacement of a stop start battery on a 2016 Ford Focus ST-3, please? 

Most retailers/suppliers advise replacement by a professional as the battery will require registering with the cars on board computer system.

Would value your thoughts please, particularly from those who have carried out this replacement. 

Thanks for reading 👍

20 minutes ago, SilverRocket said:

advise replacement by a professional as the battery will require registering with the cars on board computer system.

100% untrue for Ford vehicles. All it requires is for the Battery Monitoring System (BMS) to be reset which you can do yourself - NO tools required.

Many of us here would recommend the Yuassa as a good replacement. Usually the best price online is from Tayna Batteries. https://www.tayna.co.uk/

8 hours ago, unofix said:

100% untrue for Ford vehicles. All it requires is for the Battery Monitoring System (BMS) to be reset which you can do yourself - NO tools required.

Many of us here would recommend the Yuassa as a good replacement. Usually the best price online is from Tayna Batteries. https://www.tayna.co.uk/

Thanks for your reply, much appreciated.

Do I need to keep power to the car or is it just a case of disconnect the old battery and replace with the new and reset the bms? 

 

9 minutes ago, SilverRocket said:

disconnect the old battery and replace with the new and reset the bms? 

 

This. 
 

Just make sure you get an EFB battery. And that it’s the right size for your car. Check what you currently have fitted. You can go slightly bigger if the battery compartment will take it but never go smaller than the capacity fitted from factory. 

10 minutes ago, alexp999 said:

This. 
 

Just make sure you get an EFB battery. And that it’s the right size for your car. Check what you currently have fitted. You can go slightly bigger if the battery compartment will take it but never go smaller than the capacity fitted from factory. 

Yes thanks for your reply. I understand I require an EFB battery. 👍

...unless you have an AGM battery already fitted. Then replace it with an AGM battery. 

34 minutes ago, erictcleric said:

...unless you have an AGM battery already fitted. Then replace it with an AGM battery. 

2016 ST will be EFB. Ford have never fit AGM to the Focus. 

13 hours ago, erictcleric said:

...unless you have an AGM battery already fitted. Then replace it with an AGM battery. 

No it's an EFB 👍

13 hours ago, alexp999 said:

2016 ST will be EFB. Ford have never fit AGM to the Focus. 

Yes indeed it is Alex 👍

With the Ford Owners 15% discount the best battery is Halfords own EFB Battery, at £127.50 with 5 years warranty! 

19 minutes ago, SilverRocket said:

With the Ford Owners 15% discount the best battery is Halfords

Sorry to have to tell you but the discount at Halfords has been cut to 8%

FOC admin post last year:

 

19 minutes ago, SilverRocket said:

Yes indeed it is Alex 👍

With the Ford Owners 15% discount the best battery is Halfords own EFB Battery, at £127.50 with 5 years warranty! 

Probably cheaper to get one from tayna given unofix’s post. Yuasa make the Halfords ones. (Or at least the EFB ones)

Oh OK thanks!

On 8/19/2023 at 9:49 PM, unofix said:

Sorry to have to tell you but the discount at Halfords has been cut to 8%

FOC admin post last year:

 

Thanks for all your comments and feedback. 

All sorted 👍

Hi there,

Newbie Bondeo here, but a fair amount of experience over the years, some of it out of date.  My car is a Kuga but the problem is with my wife's Fiesta (2012 Econetic with a 1.6 diesel engine).  The battery has discharged overnight and I suspect initially that it is due to the battery's old age.  I wish to change the battery myself and I am aware that I need an EFB battery of a certain size.  The post above seems to assume that everyone knows how to reset the BMS.  I don't.

 I have got a computer memory saver that keeps the computer live by feeding a voltage through the cigarette lighter.  What I do not know is whether the computer memory has already been lost.

How is the BMS reset? 

Any advice appreciated. 

To reset the BMS after a new battery it will be one of the following two methods.

On 3/29/2023 at 8:13 PM, unofix said:

How to reset the BMS method 1                                                                         Search Tag: BMS1

 

 

Or this method:

On 3/29/2023 at 8:14 PM, unofix said:

How to reset the BMS method 2                                                                         Search Tag: BMS2

 

 

12 hours ago, unofix said:

To reset the BMS after a battery it will be one of the following two methods.

 

Thanks for that unofix.  I will try one of the methods soon.  incidentally I am from Murton.

Reporting back on my experiences with my wife's Fiesta.  The battery had completely gone and the car would not start even with my battery booster.  I called in the AA who came very promptly.  The AA man had a powerful booster pack which he connected to the car and the Fiesta started straight away.  The car obviously needed a new EFB (enhanced flooded) battery.  I went on to the internet and the best price was at the nearest GSF, a new Yuasa 7000 series battery for £101.32, with a 4year guarantee.   The AA man said that he could change the battery for £266.  At that point I decided to do it myself.  I asked the AA man about resetting the BMS.  He said that it was not necessary on Fords (they have an internal electronic self check?).  So I disconnected and removed the battery that night.  I collected the new battery the next morning and fitted it and connected it up.  The car started straight away.  The radio worked and the channels seemed to be as they were before the new battery.  The car computer seemed to be reset eg. the average fuel consumption is working through again from scratch.  Is there something I am missing?  I did not need to go through with the BMS reset.  The car, as far as I can see, is working fine.

33 minutes ago, Bondeo said:

  I did not need to go through with the BMS reset. 

Then you need to get it done ASAP 👍

I do love the AA patrol guys who are a 'Jack of all trades, and a master of none'

The Ford BMS has a days in service counter which is used to adjust the charging algorithm according to how old or how new a battery is. If there was no reason to reset then Ford wouldn't have bothered with a reset procedure !!

So at the moment your smart charging system still thinks it's dealing with and old battery, which the BMS has by now determined is very well charged. I can only guess at the possible results that might cause.

Thanks for the reply Unofix, it is much appreciated..  I had begun to realise that everything is not as it should be.  The stop/start does not work and the date display has defaulted to 03.07.2012.  Presumably that is the date that the car was first switched on.  I must admit to being happy that the car actually started.  I have now gone through the SY Diagnostics BMS reset.  It did seem to work.  I have reset the date.  When I go out tomorrow I will see if the stop/start works.  How else would one know that it is now functioning properly?

 

On 2/24/2025 at 1:22 PM, unofix said:

Then you need to get it done ASAP 👍

I do love the AA patrol guys who are a 'Jack of all trades, and a master of none'

The Ford BMS has a days in service counter which is used to adjust the charging algorithm according to how old or how new a battery is. If there was no reason to reset then Ford wouldn't have bothered with a reset procedure !!

So at the moment your smart charging system still thinks it's dealing with and old battery, which the BMS has by now determined is very well charged. I can only guess at the possible results that might cause.

Always strikes me that these Smart charging systems are not that "Smart" lol

20 minutes ago, mattsminiresto66 said:

Smart charging systems are not that "Smart"

Yes !! 👍

The same can be said about "Smart Governments" 🤣

and "Smart Energy Policies" 😂😂

Many Smart things are very dumb 🎉

For those following this post.  Having reset the BMS the Start/Stop system is now working.  Changing the battery was a relatively easy job and GSF is worth looking at for a good EFB battery (Yuasa) at a good price.  Having changed the battery it is necessary to reset the BMS for the Start/Stop to work.

My thanks to Unofix for his knowledge and prompt replies to this post.