Hello all

Sorry if this has been covered somewhere, but I did a quick search and didn't find anything.

I recently bought a 2016 Focus estate and the stop start wasn't working so I took it to the garage. The garage recharged the battery and the stop start worked again for 2 days/about 40 miles of city driving. On the 3rd day the stop start had stopped working again.

I know that the battery is going to drain quicker with city driving but I'm surprised that the stop start would stop working after such a short amount of time and distance of city driving, I think that the battery needs replacing. Is this expected behaviour or do you think that I need to send it back to the garage again?

Thanks in advance

50 minutes ago, leegypt1 said:

 I did a quick search and didn't find anything.

You sure?

https://www.fordownersclub.com/search/?q=Stop start&updated_after=any&sortby=relevancy&search_and_or=and&search_in=titles

1 hour ago, leegypt1 said:

I did a quick search and didn't find anything.

That would be the case if you searched for "My Stop Start is working" 🤣

1 hour ago, alexp999 said:

You sure?

https://www.fordownersclub.com/search/?q=Stop start&updated_after=any&sortby=relevancy&search_and_or=and&search_in=titles

I may have searched focus stop start.

I see a lot of people saying it does and doesn't work but nothing definitive, but I have just had a brainwave: I should check the date on the battery; if it's as old as the car it likely needs replacing.

I should have mentioned that the voltage on the battery with the engine off was 11.5V before I sent it to the garage, and the car was driven 175 miles to be delivered so it had a good run before I got it. With the engine running the voltage was 14.6V

11.5V is pretty low. If it’s on the original battery it has probably had it. 

Hello @leegypt1, just wondered if you had a figure in mind of the amount of fuel you will save, and therefore the reduced emissions in any given year ?

Do you think it will be more or less than £35 each year ?

3 hours ago, leegypt1 said:

II should have mentioned that the voltage on the battery with the engine off was 11.5V before I sent it to the garage, and the car was driven 175 miles to be delivered so it had a good run before I got it. With the engine running the voltage was 14.6V

If your battery reads 11.5V when there's little load being drawn,  then it's completely flat. I'm surprised it was OK starting. Voltage with the engine running isn't clear cut. You could get 14.6V by pushing a huge amount of current into a flat battery, or by a trickle into a fully charged one. But at least that shows that the car is trying to charge the battery. 

To make it worse, lead acid batteries have a form of memory, so the voltage is affected by what the battery was doing a few minutes ago.

2016 MK3.5 shouldn’t have a lead acid.. should have an EFB or AGM if it’s been swapped. 
 

I’m surprised it even started on 11.5v, ran my 1.6 diesel down to that and the starter didn’t even engage.. trickle charge sorted it out though.

EFB and AGM are types of lead acid batteries. But yes, if AGM then discharged voltages can go a little lower. 11.5V off load is still verging on permanent damage even with AGM.

A 2016 Focus should only have an EFB fitted.

11 hours ago, alexp999 said:

A 2016 Focus should only have an EFB fitted.

May be wrong but they could take an AGM right? 
wouldn’t be recommended due to being 15mm taller than standard and probably won’t fit in housing + agm isn’t that great with high heat.

although there are some new high heat ones coming out now 🤔

9 minutes ago, Foxxyblieu9 said:

May be wrong but they could take an AGM right? 

The Focus does not have a profile for charging an AGM type battery. Fitting a different type of battery will result in the AGM battery not being charged correctly, which will potentially shorten it's life. Also you will get no benefit from the battery type since the car's charging algorithm will not be able to take advantage of the AGM battery. 

6 minutes ago, unofix said:

The Focus does not have a profile for charging an AGM type battery. Fitting a different type of battery will result in the AGM battery not being charged correctly, which will potentially shorten it's life. Also you will get no benefit from the battery type since the car's charging algorithm will not be able to take advantage of the AGM battery. 

Ah didn’t realise that. Assuming it’s a similar story for lithium too? Although I have seen quite a few people swapping to lithium batteries on the RS

1 minute ago, Foxxyblieu9 said:

Assuming it’s a similar story for lithium too?

to be honest, it's probably much worse changing to a Lithium battery unless you are able to somehow load the correct charging algorithm. I would hate to think what would happen if a lithium battery was to be overcharged, become over heated and become yet another thermal runaway.

Perhaps those that have fitted lithium batteries have some third party charging/monitoring system fitted ?

22 hours ago, aesmith said:

If your battery reads 11.5V when there's little load being drawn,  then it's completely flat. I'm surprised it was OK starting. Voltage with the engine running isn't clear cut. You could get 14.6V by pushing a huge amount of current into a flat battery, or by a trickle into a fully charged one. But at least that shows that the car is trying to charge the battery. 

To make it worse, lead acid batteries have a form of memory, so the voltage is affected by what the battery was doing a few minutes ago.

Just had a look tonight, it read 11.2V this time! I didn't drive it at all yesterday. Still starts fine though. I am using the test function on the dashboard so, maybe the car's reading it wrong?

I've seen a reset procedure mentioned somewhere though, I'll have a look into that and report back tomorrow

Don’t rely on the dash display. Use a proper multi meter 

3 minutes ago, leegypt1 said:

I've seen a reset procedure mentioned somewhere though,

Do not reset the BMS unless you fit a brand new battery.

Having read through the above posts, I would say your battery is now beyond recovery and probably needs replacing. 

10 minutes ago, unofix said:

to be honest, it's probably much worse changing to a Lithium battery unless you are able to somehow load the correct charging algorithm. I would hate to think what would happen if a lithium battery was to be overcharged, become over heated and become yet another thermal runaway.

Perhaps those that have fitted lithium batteries have some third party charging/monitoring system fitted ?

Going off a couple forums that I just relooked at and This videos I can’t see that they have.

odd 🤔

9 minutes ago, Foxxyblieu9 said:

I can’t see that they have.

odd 🤔

Check out the comments.

It would seem that the RS Focus has a profile for an AGM battery.

Setting the battery type to AGM with Forscan and the car’s firmware knowing what that setting means is two very different things. 

14 minutes ago, unofix said:

Check out the comments.

It would seem that the RS Focus has a profile for an AGM battery.

Right in front of my eyes and I missed it. 
 

should’ve gone to spec savers 😅

15 minutes ago, alexp999 said:

Setting the battery type to AGM with Forscan and the car’s firmware knowing what that setting means is two very different things. 

May be asking a silly question but is that not exactly what that setting is for?

would be kind of a useless setting if it didn’t actually change the charging profile although I suppose it is an older BMS 🤔

5 minutes ago, Foxxyblieu9 said:

May be asking a silly question but is that not exactly what that setting is for?

would be kind of a useless setting if it didn’t actually change the charging profile although I suppose it is an older BMS 🤔

Forscan shows a lot of settings that are an interpretation of the developer based on other vehicles. If a car never came from factory with AGM battery there is nothing to compare against, no way of knowing the firmware would understand the change in setting. I frequently see Forscan offering battery options which are wrong for the model in question or change from version to version. I try and only make changes that can make obvious verifiable changes or can be compared against other cars of the same model but different spec that have the exact same firmware calibration. 
 

Forscan didn’t even recognise the factory setting for my battery. 

40 minutes ago, unofix said:

Do not reset the BMS unless you fit a brand new battery.

Having read through the above posts, I would say your battery is now beyond recovery and probably needs replacing. 

Thanks, this is what I thought. I'll call the garage tomorrow and have them take another look.

They told me that they had to charge it overnight to rule out a flat battery rather than a worn battery, but aren't there ways they can test that without having to charge it overnight? I felt messed around

Just now, leegypt1 said:

Thanks, this is what I thought. I'll call the garage tomorrow and have them take another look.

They told me that they had to charge it overnight to rule out a flat battery rather than a worn battery, but aren't there ways they can test that without having to charge it overnight? I felt messed around

Most places should have a battety tester which can give some statics.

 

if they don’t have one I’d take it somewhere else that does have one and get them to test it.