Advice Needed for Battery Change

[Dave666]

The 2019 Focus SA Active was a no start this morning and made all sorts of strange noises.

The terminals were all good, so I tested the battery with the multimeter - 10.5 volts = very dead battery.

I found a compatible battery replacement, but I am a bit unsure about any issues with changing the battery. Specifically whether I need to reset the BMS (Battery Monitor System)?

Do I need to reset the BMS if I dont use the cars auto start/stop?
If yes - how do I reset the BMS?
Any other tricks or traps to be aware of?

Cheers
Dave

[russellw]

From your owners manual

To disconnect or remove the battery, do the following:

1. Apply the parking brake and switch the ignition off.

1. Switch all electrical equipment off, for example lights and radio.

1. Wait a minimum of two minutes before disconnecting the battery.

Note: The engine management system has a power hold function and remains powered for a period of time after you switch the ignition off. This is to allow diagnostic and adaptive tables to be stored. Disconnecting the battery without waiting can cause damage not covered by the vehicle Warranty.

1. Disconnect the negative battery cable terminal.

1. Disconnect the positive battery cable terminal.

1. Remove the battery securing clamp.

1. Remove the battery.

1. To install, reverse the removal procedure.

Note: Before reconnecting the battery, make sure the ignition remains switched off.
Note: Make sure the battery cable terminals are fully tightened.
If you disconnect or replace the vehicle battery, you must reset the following features:

• Window bounce-back. See Power Windows - Vehicles With: One-Touch Open and Close Front Windows .
• Clock Settings.
• Pre-set radio stations.

Unlike earlier BMS models it doesn't look like there are any steps required to reset that system.

[Dave666]

Thanks Russell.

I did actually check the manual. Must have had a "man look" because I didnt find it first time.

Thanks Again

[stefcio007]

You can also reset the BMS system using the following procedure -
Ignition on, don’t press clutch/start engine, then flash the headlights 5 times then press the brake pedal 3 times, after approximately 15 secs the battery light should flash, once it does ignition off- BMS reset.

[Dave666]

New battery went in ok, and everything is working and charging well.

The only strange thing is, we now have to manually turn off the engine start/stop system every time we start the car. Its a real pain, however, I dont think you can turn this off permanently?

We have owned the car for about 2 years and during that time we never had to manually turn off the start/stop function? I assume the battery volts were low over this total 2 years, so the system dosnt run the start stop.

I preferred it when the volts were low

[stefcio007]

It’s been a while since so played with ForScan but remember there was a “default state” every time the car starts that could be set such as which drive mode, default drive mode is Normal but apparently you can change it to Eco or Sport. I assume there’s also an option for start stop. Otherwise I’ve seen looms that you connect between the existing loom and your drive controls but they disable start stop entirely, as in you can’t use the button to turn it on either. Maybe worth looking in to one of those?

[DeKa]

Originally Posted by Dave666

New battery went in ok, and everything is working and charging well.

The only strange thing is, we now have to manually turn off the engine start/stop system every time we start the car. Its a real pain, however, I dont think you can turn this off permanently?

We have owned the car for about 2 years and during that time we never had to manually turn off the start/stop function? I assume the battery volts were low over this total 2 years, so the system dosnt run the start stop.

I preferred it when the volts were low

Correct - Start Stop doesn’t work when the battery isn’t healthy.

I use Start Stop to my advantage to save a little bit of fuel at times - I start the car and press the button to disable Start Stop. Most of the time it stays like that but if I get stuck at a long traffic light cycle I press the button again to let the engine stop, and then again to disable Start Stop when I move off.

[prydey]

Stop/start may not make much difference individually but on a global scale, less cars sitting idling will add up.