I fit this in mine:

YBX7096 Yuasa EFB Start Stop Car Battery 12V 75Ah

<h4>Yuasa</h4> <i>Advanced Engineering, Premium Quality, Unmatched Reliability</i> GS Yuasa located in Japan, all started in 1895 and is one of the biggest battery manufacturers in the world. Manufacturing batteries for the automotive, commercial and infrastructure markets. Yuasa Battery, Inc...

www.tayna.co.uk

 

thanks, i see that ones a 700/75 too

 

Yuasa make the Halfords branded one. But the Yuasa is a lot cheaper from Tayna.
A lot of us have fitted this battery to Mk4 on another forum (non ST mostly) it’s a lot more reliable than the one Ford fit from factory.

 

Bought 3 Ford's wont buy another. Just got off the phone to Ford Customer Relations regarding the latest issue I have had with my MK4.5 Ford Focus ST I bought a year ago.

Matrix LED headlights failed within 6months, which meant driving on single carriageway country roads at 30mph (no high beams). When I rang around dealers they said they were unaware of a known issue - yet someone on a Ford Owner's website had found the service number for it for me no problems. Contacted my point of sale dealer, and the first slot they had was in 3 months time (booked up apparently). Had to drive 30miles to another dealer and back. Was given a transit van as a courtesy car as they had no cars available. The software they were using failed so the car had to be kept overnight. They did fix it in the end, which I was obviously pleased with.

The battery has degraded over time to the point the car goes into energy saving mode after less than 24hrs. Meaning you get into a car with no lights at night until the engine turns on. The battery never reached a state of charge sufficient for the engine to cut out since day 1 of ownership. Rang dealers they said the car needs to hit specific conditions for it to work - so motorway journeys and 365 days of ownership and it never reached the optimum conditions. I managed to get a dealer to look at it at the first service and they assured me the battery charged fine, and there was nothing wrong with it; essentially I imagined the FordPass warnings, the dash energy saving warnings and the fact the car reports it has done 0 stop/starts.

In the end got a new battery fitted outside of Fords, and surprise surprise the car is now fully functional almost a month later. Worth pointing out that the Ford Owner's Forums are littered with messages about battery issues on Ford's. Apparently all these customers have active imaginations too. Ford wouldn't reimburse me for the £110 battery I had to buy for a 1 year old car.

My experience of Ford is they will do everything they can to weasel out of fixing things under warranty - I therefore see the warranty as a marketing ploy, and not a guarantee. Anyway lesson learnt, next time it is a Honda Civic Type R for me, and wave goodbye to the big blue oval with no regrets.




I went for varta 700cca 70ah. looks like mk4 had this and the miserable gits went for 600cca 60ah in mk4.5 . They also removed the plastic drains to the wheel arch covers in the front wings too .You will need to reprogramme it using forscan or get a garage. Bsm reset won't pick up the new battery size. If you need info let me know

 

I had exactly the same problem with my 8 month old focus ST 4.5.
Stop start never worked even after a 200 mile moteorway run.
Dealer told me I wasn't doing enough miles. Then the cold weather arrived. Ford pass kept alerting me of low battery and dashboard warning too.
They charged the battery. Lasted 48 hours. I complained profusely to the dealer principal. He said Ford and his technicians know there is a problem with batteries and I had it changed. Probably because I and my family had purchased over 10 cars from this dealer. See how long it lasts. Be my last Ford!

 

yes that wouldnt suprise me, fitting the minimum battery they can get away with i know someone who can do the reprogamming so thats no problem but like you say it shouldnt be necessary on a nearly new car,i had my mk3.5 for nearly 6 yrs,still on its orig battery with no problems at all

 

Same here. The MK3.5 was a cracking car. On the smaller engine sizes the clutch slip recall was obviously a black mark and the head gasket on the RS focus on release.

Reducing the battery size is a bit of a joke. My mk4.5 has heated seats, steering and all the gismos.........yet my wife's 1.0 100PS ecoboost Fiesta had a bigger battery. I've noticed when you turn on the power to the car without ignition, there is like a continuous 14amp draw. God knows what is chewing that up

Most likely the short battery life is Ford setting the alternator to only charge the battery to 80% state of charge (can be changed on ForScan), smaller batteries and the fact that the car is probably busy talking back to the mother ship every 5minutes sharing data with the world. If I could be faffed, I would take my Hall effect current meter, and look around the wiring looms with the car powered down. However, for what gain - not like Ford would do anything if you found the issue anyway.

 

Be really careful changing battery values. They change depending on calibration (firmware) there is not a one size fits all. I changed mine by looking at the asbuilt of a diesel built around the same time using the same calibration and copied that.
Forscan UI values are often wrong it didn’t recognise my factory as built value or the one I changed it to.
That said, I did it more as an OCD/because I could. It’s really not necessary. It makes 1 or 2% difference to the SoC calculation. Just change the battery reset the BMS and that’s enough.

 

i was going to say the mk4.5 will be the last focus i buy also,but then it will be as there wont be any more made

 

hello again mate.

sorry to raise this thread from the dead, but I have a 100% dead Focus ST 4.5 that seems to have the issues outlined in this thread… in a way I hope it does, as the alternative feels like an ECU fault or similar with the errors it threw.

I just wanted to ask what battery you went for in the end? I don’t have coding facilities and the car is dead on the road, so I need a plug and play option - which I suppose might even just be an OEM replacement and I kick the issue down the road.

thanks
Matt

 

Fundamentally these cars keep drawing 100-200mA on the battery 24/7 might reduce a bit in energy saving mode. Unless you drive the car regularly you are going to end up with a dead battery. Smaller batteries will die quicker.

My wife's fiesta mk8 doesn't have this. 0 draw after the car fully shuts downs.

I heard that when the mk4 came out people had 700mA draws and it needed a software update if I recall the video (German chap with subtitles) . He posted a lot on mk4 focus.

 

I have had my brand new 4.5 built this February for 3 weeks. It had stood in the dealers compound for two weeks. I did around 100 miles first week and didn’t use it again until Friday so stood for two weeks. So basically this car has stood unused most of the time since being built. It has never sent any sleep mode or shutdown notices, I started it Friday and drove 1/2 mile to a junction where it immediately activated the stop function even though it was still effectively cold, the stop start worked consistently just as it did all the time during the first 100 miles. What I am trying to say is this is a car that has mostly stood since being built yet shows no battery issues whatsoever.

They seem to have done something with the latest version wether it is just software or updated hardware who knows. But I know my others would have sent messages, gone into sleep mode and the stop/start stopped working in that period, but not this one. There has always been a benefit in getting last versions of model runs imho

 

Presumably it isn't software or they'd patch all cars on service to save fitting new batteries. So perhaps it is a hardware update. Be interesting to know if and when this happened if theory is correct. What battery is in your mk4.5 2025 Feb ?

 

the last update must have altered something because i never got round to replacing the battery as im on the lookout for another car now and have only had one sleep mode warning since the update, i used to get at least 3 per week before that, the stop start has never worked but im not bothered about that

 

Puma’s and especially mhev versions are even worse. Totally unnecessary battery replacements going on there. I used to get sleep mode messages from my previous mk4’s but never failed to start or go flat even after many weeks in the garage. I used to do a BMS reset when the stop start packed in and that usually gave months of zero problems afterwards

 

After a complete battery (12v) failure a month ago on my wife’s Kuga, I’ve just logged into FordPass and received this notification…no available resolution as yet.

Great.

 

"May" have a problem. Nice.Oh and don't use that key feature you purchased, while we are waiting to get our butts into gear. Ford have really dropped the ball.

I remember when the first mondeo and focus came out. Ford were very much on their A game then. I get the feeling they only care about the US pickup / ute / suv style cars now as that is where the real sales are. The stuff for the European market went downhill. The mk3 focus had loads of issues with coolant pipes etc I waited for mk3.5. I heard mk4 had loads of issues waited for mk4.5.

Mind you just realised the US market argument falls flat with the kuga as they sell that as the escape over the pond.

Puma’s and especially mhev versions are even worse. Totally unnecessary battery replacements going on there. I used to get sleep mode messages from my previous mk4’s but never failed to start or go flat even after many weeks in the garage. I used to do a BMS reset when the stop start packed in and that usually gave months of zero problems afterwards

yeah to be fair I've had it go into power saving mode weekly but after 2 weeks it fired. Pretty sure the battery must have been down to 50% by that point or worse. Doesn't fill you with confidence in the winter. Also sucks getting into a dark car at night when you've paid good money etc

You wonder how much environmental damage has been caused with all the premature battery replacements with batteries that continually drain down to damage inducing levels.

Keep an eye put of for legal firms in future saying did you ever own or lease a vehicle. No win no fee etc

 

as already mentioned,when buying a new car nowadays its best to wait at least a couple of yrs until all the bugs and problems have been rectified,now production has finished the focus should be the great car it always promised to be but was constantly let down by electrical/battery problems

 

I feel the root cause of the battery issues in the Mk4 & 4.5 is the smart charging system limiting charge to 80%. I have changed mine to 90% and fitted a higher amp hour battery.

 

see how you go in a few months . I did it and ended up back at square 1 after 6months . fundamentally on mine it is constantly draining battery at background level so you can charge it all you like if you leave it more than a week it will go into battery saver.

 

yes the smart charging isnt smart at all another stupid idea,in the good old days before all this technology a battery lasted for many many years if you looked after it

 

I went for varta 700cca 70ah. looks like mk4 had this and the miserable gits went for 600cca 60ah in mk4.5 . They also removed the plastic drains to the wheel arch covers in the front wings too .You will need to reprogramme it using forscan or get a garage. Bsm reset won't pick up the new battery size. If you need info let me know

How do you do the reprogramming through forscan?

Bought 3 Ford's wont buy another. Just got off the phone to Ford Customer Relations regarding the latest issue I have had with my MK4.5 Ford Focus ST I bought a year ago.

Matrix LED headlights failed within 6months, which meant driving on single carriageway country roads at 30mph (no high beams). When I rang around dealers they said they were unaware of a known issue - yet someone on a Ford Owner's website had found the service number for it for me no problems. Contacted my point of sale dealer, and the first slot they had was in 3 months time (booked up apparently). Had to drive 30miles to another dealer and back. Was given a transit van as a courtesy car as they had no cars available. The software they were using failed so the car had to be kept overnight. They did fix it in the end, which I was obviously pleased with.

The battery has degraded over time to the point the car goes into energy saving mode after less than 24hrs. Meaning you get into a car with no lights at night until the engine turns on. The battery never reached a state of charge sufficient for the engine to cut out since day 1 of ownership. Rang dealers they said the car needs to hit specific conditions for it to work - so motorway journeys and 365 days of ownership and it never reached the optimum conditions. I managed to get a dealer to look at it at the first service and they assured me the battery charged fine, and there was nothing wrong with it; essentially I imagined the FordPass warnings, the dash energy saving warnings and the fact the car reports it has done 0 stop/starts.

In the end got a new battery fitted outside of Fords, and surprise surprise the car is now fully functional almost a month later. Worth pointing out that the Ford Owner's Forums are littered with messages about battery issues on Ford's. Apparently all these customers have active imaginations too. Ford wouldn't reimburse me for the £110 battery I had to buy for a 1 year old car.

My experience of Ford is they will do everything they can to weasel out of fixing things under warranty - I therefore see the warranty as a marketing ploy, and not a guarantee. Anyway lesson learnt, next time it is a Honda Civic Type R for me, and wave goodbye to the big blue oval with no regrets.

You would be better off with the Civic for sure. Unfortunately that car plays in the league of its own, both in terms of driveability and price. If you were to buy an FK8 used, be aware of the infotainment crashes and the gearbox grinding issue (which I might add, was not treated very well by Honda, despite the many customer complaints). The FL5 does not have these issues

 

How do you do the reprogramming through forscan?

Ive read that you can do the following(Ford Focus MK4 Battery - Page 2 - FORScan forum):

bodycm for as built (hex stuff) .
take backup (saved the settings as abt file)
mk4.5
726-02-01 = 1111 | 0909 | 0C70
600cca 60ah and h5(small size)
11(hex) = 17(decimal)

sounds like mk4 was
726-02-01 = 1C1C | 0909 | 0C86
1C (hex)= 28 in dec

write it

Then go into body control module (not the "as built" hex one) with the standard key value pairs

search for battery

Change "battery type factory" from 17 to 28 (shows as 720 CC 70ah h6)

While you are there you might want to change your Battery State of Charge % from 80% to 90-95%(based on what I have seen on forums people have done). Seems Ford set it so the alternator stops charging the bat when it gets to 80% to improve fuel economy and/or preserve battery life.

Then reset the bms using the headlight/brake trick or use forscan.

You would be better off with the Civic for sure. Unfortunately that car plays in the league of its own, both in terms of driveability and price. If you were to buy an FK8 used, be aware of the infotainment crashes and the gearbox grinding issue (which I might add, was not treated very well by Honda, despite the many customer complaints). The FL5 does not have these issues

test drove the civic type R (model before latest with the £47k price tag and the waiting list longer than Fords list of outstanding field actions) before I went for ST. Has to be said that thing is built for the track. Way better handling and the engine is something else. I believe they squeezed another 40bhp out of it on the new one. Also I see the Focus ST track pack gets floored by a standard Civic Type R on every circuit hot lap review I've seen. Appreciate if you lob a mountune on focus you can take it to 365bhp (Focus RS territory) but I found the honda front diff way better than Focus....so can use more of that power on corner exit. Also the Type R beats the Focus RS (with awd and the extra power) round the Nordschleife. The gearbox on civic is a work of art n'all. Main benefit I see on focus was it was nicer inside, had 5 seats not 4, cheaper and a better all rounder (more comfortable for day to day). Must say why oh why do Ford not allow ppl to select Sport mode but with the dampers set to Normal. VW, Hyundai and Honda both allow it.Civic is stiff and twitchy and hates you if you don't drive it fast. Read a review saying it is too widefor British B roads, almost as wide as an Audi etron. Honda are super reliable, built well and hold their value better than precious metals, which is why I will be going that way next time.

Guess the other option is i30N if my wife won't let me spend that kinda a money