Hi.

My car is at Ford for it's convenience check.

They have said that the battery is low and needs a trickle charge and then the BMS will need to reset.

They will do this for £80. Does this seem fair?

I am not even slightly technical but is this something I could do myself?

Fiesta ST line 1.0L MHEV

Cheers

The BMS should not be reset unless the battery has been replaced.

You can charge the battery yourself at home as long as you have access to a mains plug socket near the car.

Thanks for the quick reply Tom'sFocus.

They said it was 48% and the air-con wasn't working so would need to be trickle charged and the BMS reset.

Yes I have a socket near the car in the garage.

Can you / anyone recommend a suitable charger and a basic guide for charging.

I understand a blast on the motorway doesn't help these things anymore.

Cheers

Resetting the BMS resets the battery age to zero. That means the charging system will treat it as a brand new battery, which will reduce it's lifespan.

Generally the car should update the State of Charge (SOC) after mains charging within a couple of drives, so the BMS should not be reset in this case.

If the SOC does not update then you would have to reset the BMS, but only as a last resort. That is done using a simple button sequence, so you can do it at home if necessary.

Maypole chargers are often recommended on here. This one is the newer version of the one I own myself.

MAYPOLE MP7425 Electronic Car Battery Charger 5A Fast Trickle 6v / 12v 5 AMP | eBay UK

It really is as simple as clipping the red clamp onto the red battery terminal, and the black clamp onto the chassis earth point. The switch on the wall plug and leave it to charge overnight.

18 minutes ago, Casbantam said:

They have said that the battery is low and needs a trickle charge and then the BMS will need to reset.

They will do this for £80. Does this seem fair?

Well, my local dealer has in the past charged mine foc and didn't misinform me about the BMS either!

NB You need to use a "smart" charger. If you don't have one, you can buy one for well under £80**. Based on the experience of most Fiesta Mk 8/8.5 owners, it'll get plenty of use!😀

**Most expensive options are the C-tek MXS 5 and NOCO Genius 5, Maypole 7423A or 7425 are cheaper options, all have their fans on here. Widely available via Amazon, Halfords Ebay, etc.

All will come with instructions but ensure you connect the negative to an earth point on the chassis, not the battery negative terminal, to avoid confusing the BMS.

Let the charger run through its full cycle preferably overnight.

A motorway blast is of little use with modern charging systems as you suggest. A varied drive, with lots of opportunities for engine braking, is far better for charging.

Brilliant.

Thank you TomsFocus and EricBloodaxe you've been most helpful.👍👍

8 minutes ago, Eric Bloodaxe said:

Well, my local dealer has in the past charged mine foc and didn't misinform me about the BMS either!

NB You need to use a "smart" charger. If you don't have one, you can buy one for well under £80**. Based on the experience of most Fiesta Mk 8/8.5 owners, it'll get plenty of use!😀

**Most expensive options are the C-tek MXS 5 and NOCO Genius 5, Maypole 7423A or 7425 are cheaper options, all have their fans on here. Widely available via Amazon, Halfords Ebay, etc.

All will come with instructions but ensure you connect the negative to an earth point on the chassis, not the battery negative terminal to avoid confusing the BMS.

Let the charger run through its full cycle preferably overnight.

A motorway blast is of little use with modern charging systems as you suggest. A varied drive, with lots of opportunities for engine braking, is far better for charging.

Might have to go to your dealer in future😁