Fiesta ST Forums banner
1 - 20 of 28 Posts

·
Registered
Joined
·
1 Posts
Discussion Starter · #1 ·
Hello guys. I’m changing the battery on my mk7 st, are the batteries a straight swap out and drive? I’ve had a look online and in some cases, the battery needs to be registered on the system for it to work at full capacity. Is this the case with fiestas or are they a straight swap? I’m replacing it with a Yuasa HSB010 Silver 12V Car Battery 5 Year Guarantee.
 

·
Registered
Joined
·
140 Posts
I am very sorry but this is not true. In Fact you must reset the learned values of the battery monitor system. You find this Sensor on the Minus/Ground Contact Cable ,a connector with 2 wires. Every Fiesta ST 182/200 has it.
You will reset the Age of Battery to zero Days in PCM Powertrain Control Module with following steps
Ignition on, press 5 times Rear fog light switch, then press 6 times or more hazard flasher switch, if you make it correct,the battery light in the instrument cluster will flash 3 times.
See my YouTube Video where I show you how to do it.
 

·
Registered
Joined
·
140 Posts
I am very sorry that you don't understand the modern car. I am a Ford mechanic since the year 1999,i know a few important things from Ford. If you put a new battery in a modern Ford vehicle it is very important to reset the BMS System. It is very easy to do. This is official Order from Ford Motor Company. There is a TSB Technical Service Bulletin Number 40/2013 where you or a mechanic can read very important information about battery system,Battery monitoring system, how it works and so on.
 

·
Registered
Joined
·
140 Posts
Don't waste your time.. The garage fitted my battery was a straight swop plus I fitted a smaller one to get the car going until the new one went in.
I am very sorry , but I must say your garage is crap if they didn't tell you that you have a BMS Sensor in your car.
At Ford we have the BMS Sensor System since the Year 2010,welcome to the year 2022 my friend. Wake up! Learn the truth!!!
 

·
Registered
Joined
·
140 Posts
Hello guys. I’m changing the battery on my mk7 st, are the batteries a straight swap out and drive? I’ve had a look online and in some cases, the battery needs to be registered on the system for it to work at full capacity. Is this the case with fiestas or are they a straight swap? I’m replacing it with a Yuasa HSB010 Silver 12V Car Battery 5 Year Guarantee.
Method to reset BMS
NOTE:NOTE: Do not conduct the reset unless a battery has been replaced, refer to <When should the BMS be factory reset?>.
If the sequence is interrupted with other button or pedal presses for any reason, the steps must be repeated from the beginning.
Vehicle has a rear fog light button:
1. Enter vehicle and perform the steps 2 to 4 within 10 seconds.
2. Switch ignition ON, engine OFF (Position II).
3. Push and release the rear fog light switch five times.
4. Push and release the hazard warning light switch three times.
5. If successful the charging system warning light on the instrument cluster will blink three times within the next 15 seconds.
6. BMS reset done
Vehicle does NOT have a rear fog light button:
1. Enter vehicle and perform the steps 2 to 4 within 10 seconds.
2. Switch ignition ON, engine OFF (Position II).
3. Pull and release high beam switch five times.
4. Press and release brake pedal three times.
5. If successful the charging system warning light on the instrument cluster will blink three times within the next 15 seconds.
6. BMS reset done
 

·
Registered
Joined
·
2,644 Posts
I was unaware of that process or requirement. What is the downside of not having the system relearn?

I've changed a few batteries in different STs and they've all been fine with just a straight swap. I have a Yuasa battery in mine after it was replaced in 2019, still healthy.

Edit: It seems that BMS reset is only required on cars with AGM batteries for start/stop. This makes sense given the constant on/off. I'm yet to find anything that suggests it's also required for standard fiestas without the system, such as the ST.
 

·
Registered
Joined
·
2,644 Posts
Looks like it's correct, although Ford's manual suggests either doing it via Forscan or by detaching the sensor on the negative cable for 4-6 hours to force a relearn:

If the vehicle battery is replaced, it is very important to perform the battery monitoring system reset using the scan tool. If the battery monitoring system reset is not carried out, it holds the old battery parameters and time in service counter in memory. Additionally it tells the system the battery is in an aged state and the may limit the Electrical Energy Management system functions. For more information, refer to: Battery and Cables - System Operation and Component Description (414-01 Battery, Mounting and Cables, Description and Operation).
NOTE: The battery monitoring sensor relearns the battery's state of charge within 4-6 hours after the sensor is removed from the battery. For additional battery monitoring sensor information, refer to section 414-00.
 

·
Registered
Joined
·
140 Posts
Looks like it's correct, although Ford's manual suggests either doing it via Forscan or by detaching the sensor on the negative cable for 4-6 hours to force a relearn:
Not true. The only way to reset the counter to zero Days is to push switches as you can See in my YouTube Video or you can read in TSB above. You can also use forscan to reset the counter to zero Days. If you don't have done it yet you can do it now. But you must do it. Its better for the battery, if the PCM (or at other Ford the BCM Body Control Unit) knows how old the battery is. Its fine tuning.
 

·
Registered
Joined
·
1,581 Posts
...oh, and a potentially stupid question too...

If its reset to zero on installation, how does it retain this information if the battery is disconnected for any engine/electrical work or, say, the battery runs flat?
 

·
Registered
Joined
·
2,644 Posts
Not true. The only way to reset the counter to zero Days is to push switches as you can See in my YouTube Video or you can read in TSB above. You can also use forscan to reset the counter to zero Days. If you don't have done it yet you can do it now. But you must do it. Its better for the battery, if the PCM (or at other Ford the BCM Body Control Unit) knows how old the battery is. Its fine tuning.
Interesting your method isn't listed in the service manual for the car, why is that?

What does detaching the sensor do in that case? To me it reads as if it hard resets the learnt parameters:

The battery monitoring sensor relearns the battery's state of charge within 4-6 hours after the sensor is removed from the battery.
 

·
Registered
Joined
·
140 Posts
@Jorg - I know this is a Mk7 thread but did this requirement continue into the Mk8's?... lots will be at or coming up to their 1st battery change soon.

Cheers in advance👍🏻
Yes,the same Procedere is for the Fiesta mk8. I have done the second manual, with the high Beam and brake Switch.at Every Ford Vehicle that has an BMS Sensor at the ground Cable ,you MUST Do it!!! Very Important for the health of your New battery.
 
1 - 20 of 28 Posts
Top