Our battery went flat today randomly. 2018 1.0 ecoboost stop/start. Got it jumped and then took it to a garage half hour later, tested it and it was 47% health 75% charge. He did say that it probably needs changing soon as it’s below 50% health. 

But said that it would be more expensive than normal as it needs fitting and programming to the cars computer otherwise it would still think it’s the old battery.  
 

is this the case? Or can I do it myself? I’ve replaced a standard non stop/start a few times but not one of these 

19 minutes ago, Paddyposh89 said:

Our battery went flat today randomly. 2018 1.0 cohost stop/start. Got it jumped and then took it to a garage half hour later, tested it and it was 47% health 75% charge. He did say that it probably needs changing soon as it’s below 50% health. 

But said that it would be more expensive than normal as it needs fitting and programming to the cars computer otherwise it would still think it’s the old battery.  
 

is this the case? Or can I do it myself? I’ve replaced a standard non stop/start a few times but not one of these 

Doesnt need "coded" to anything. Buy the correct battery, charge it fully before you fit it, then do a simple BMS reset, its simple dont pay some rip off garage to do it for you, do it yourself.

37 minutes ago, Paddyposh89 said:

But said that it would be more expensive than normal as it needs fitting and programming to the cars computer otherwise it would still think it’s the old battery.  

Was he a comedian ? 🤣

Buy a Yuasa battery and a 10mm spanner if you haven't already got one. Then spend twenty minutes to fit the battery and reset the BMS no tools or computers required. Total cost around £110 and 99p for an Lidl spanner.

https://www.tayna.co.uk/car-batteries/yuasa/ybx7110/

Thanks both. Would this be suitable ? 

3 minutes ago, Paddyposh89 said:

Would this be suitable ? 

It would do, but you can get a more powerful battery (see my link above)

Just now, unofix said:

It would do, but you can get a more powerful battery (see my link above)

Thanks yep just seen after I posted ! Appreciate it. And the reset looks simple too

2 minutes ago, unofix said:

It would do, but you can get a more powerful battery (see my link above)

Found it on GSF and reckons it won’t fit based on reg, don’t see why not as it looks the same just more powerful 

Just now, Paddyposh89 said:

Found it on GSF and reckons it won’t fit based on reg

100% will fit. It is the battery used in the Focus 2.0 Diesel. The cars use the same battery tray and the same connections. I've just fitted the exact same battery to my son in-laws 2017 Focus ST

11 minutes ago, unofix said:

100% will fit. It is the battery used in the Focus 2.0 Diesel. The cars use the same battery tray and the same connections. I've just fitted the exact same battery to my son in-laws 2017 Focus ST

Thanks for the info, much appreciated. Dunno why reg check says otherwise. Will look to order one 🤝

3 hours ago, Paddyposh89 said:

Thanks for the info, much appreciated. Dunno why reg check says otherwise. Will look to order one 🤝

Registration check will not say it fits because it's not standard fitment for your vehicle. As said previously, it will fit!

Hi just a bit of advice before you purchase a new battery.measure the height of your existing battery because a lot of the battery websites recommend a 175 mm tall battery. I have a mk8 fiesta and got caught out mine is 190mm tall even though website recommended 175mm. I believe that the mk8 fiesta battery tray varies from model to model so best to check.

On 4/30/2025 at 5:49 PM, unofix said:

100% will fit. It is the battery used in the Focus 2.0 Diesel. The cars use the same battery tray and the same connections. I've just fitted the exact same battery to my son in-laws 2017 Focus ST

Sorry just to check, my current OEM one appears to be 278mm long. One you mentioned is 317mm

 

shouldnt be an issue assuming it’ll be ok as you say?

 

the other I linked which is slightly less powerful what’s the downside just generally less life?

Just wanted to triple check before ordering (was made redundant and had a lot to deal with so put it off and it happened again today whilst I was at the shops!)

 

So keen to get sorted this week

The Focus 2017 models all use the same size battery tray which can accommodate any of the batteries that the Focus uses.

To save money Ford will always fit the lowest powered battery they can during production.

1 minute ago, unofix said:

The Focus 2017 models all use the same size battery tray which can accommodate any of the batteries that the Focus uses.

To save money Ford will always fit the lowest powered battery they can during production.

Thanks yeah that makes sense. Would that be the same for 2018 models too I presume?

1 minute ago, Paddyposh89 said:

Would that be the same for 2018 models too I presume?

All Focus Mk3.5 up to 2018 use the same size battery tray.

All Focus Mk4.0 from 2018 use the same size battery tray.

On 5/27/2025 at 11:49 PM, unofix said:

All Focus Mk3.5 up to 2018 use the same size battery tray.

All Focus Mk4.0 from 2018 use the same size battery tray.

Might be a stupid question but how do you know if it’s MK3 or 4? Was looking at BMS resets you sent in another thread and notice there’s two different ways

 

battery should be here tomorrow, it states it will arrive charged. I don’t have a charger. Should I be ordering a certain type of charger and connect it to the battery prior to fitting? Will need to use it tomorrow so hoping not to have to do it but wanted to check 

46 minutes ago, Paddyposh89 said:

Might be a stupid question but how do you know if it’s MK3 or 4?

In pics below, silver one is a Mk 4, white one is a Mk 3:

 

 

 

On 4/30/2025 at 5:04 PM, Paddyposh89 said:

Our battery went flat today randomly. 2018 1.0 ecoboost stop/start. Got it jumped and then took it to a garage half hour later, tested it and it was 47% health 75% charge. He did say that it probably needs changing soon as it’s below 50% health. 

But said that it would be more expensive than normal as it needs fitting and programming to the cars computer otherwise it would still think it’s the old battery.  
 

is this the case? Or can I do it myself? I’ve replaced a standard non stop/start a few times but not one of these 

hi im 74, easy job bought on amazon efb battery, Tanya site is good to took 20 mts, reprogram easy go on u tube tell u how its dead easy, Halfords wanted 189 fitted, only cost me 75,bought and free delivery,go for it

On 5/27/2025 at 11:46 PM, Paddyposh89 said:

Thanks yeah that makes sense. Would that be the same for 2018 models too I presume?

put reg in on amazon or e bay they tell you what fits your model easy to change yourself, and easy to reprogram get on you tube diy,half the cost

put reg in on amazon or e bay they tell you what fits your model easy to change yourself, and easy to reprogram get on you tube diy,half the cost

On 4/30/2025 at 5:24 PM, Delboy777 said:

Doesnt need "coded" to anything. Buy the correct battery, charge it fully before you fit it, then do a simple BMS reset, its simple dont pay some rip off garage to do it for you, do it yourself.

Hi just on the charge point, it’s arriving today and I need to use it today but don’t have a charger. Is there any issue with me not fully charging it first? I can buy a smart charger tomorrow but will need to use the car beforehand - or is there a big detriment to it

New battery in, took around half hour maybe total. What a pig to get in! But got there. Thanks @unofix for the recommendation 

 

will try get hold of a smart charger in next day or two but got a couple of local trips to do first