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Mk3 Focus battery replacement


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For the second time in around 3 weeks the battery on my daughter's 2013 1.0 Ecoboost has gone flat whilst I have been working on it, so I'm guessing it's on it's way out as it's the original battery (I was only hoovering it out today with the doors open for about 15 minutes, so I'm fairly happy it's nothing I've done !!).

As I work for a motor factors I will get a replacement from work on Monday and will swap it over but can someone please confirm that the BMS re-set procedure is as follows :-

1) Ignition on

2) Sidelights on

3) Press rear fog light switch 5 times

4) Press hazard light switch 3 times 

5) Wait for battery light to blink twice. 


Thanks guys.

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Cheers YOG...will get the new one tomorrow and charge it up tomorrow night and then hopefully fit it on Tuesday.

Is the above procedure correct for the Mk3 1.0 Ecoboost as there are different procedures for different models ??

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On our 62-plate Mk3 1.0 Ecoboost I fully charged the battery then successfully used the following to reset the BMS:

Ign on for 10 secs

Press rear foglight switch 5 times

Press hazard switch 3 times

Wait 10 secs, battery light flashes

Ign off.

I didn't need sidelights on.

@JW1982recommends fully charging the battery before performing the reset. Normally one would connect the charger negative lead to the body rather than direct to the battery so that the charge current goes through the BMS sensor on the battery negative post. However if resetting the BMS after charging I guess this is not important.

Since replacing the battery and using the above procedures Stop/Start has been working reliably on our car.

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Cheers mjt....I got a Yuasa YBX7100 from work today and as per the above recommendations am currently topping up the charge on it before fitting it tomorrow morning 👍

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