Hi All,

That's just how it feels, like when you screwed up an iphone jailbreak and you ended up with a fancy paper weight (if you know, you know...). So what I mean here for the car is that nothing electrical works. Doors dont close/open, the boot doesn't open either, no lights, no nothing. I also plugged in an OBD2 scanner but wouldn't get power at all. 

So it first happened Saturday, the car was running fine and went for some groceries after 30 miles on the road. When I came back an hour later the car just turned itself off before I could push the start button. RAC used a battery booster to jumpstart it and drove it for an hour or so to get the battery recharged. I thought the kids had left something on and got the battery drained.

Yesterday, I went to go out and same thing happened, no electricity at all. So today I got the multimeter out to check how low did the battery got to and I was surprised to see that it was at 12.38v.... so pretty normal for a car battery isnt it?

In my very limited experience with cars (I did work a bit on motorbikes but never cars) I deduct the following:

1) The battery seems to be ok as it managed to keep a high enough voltage over 2 days unless 12.38V is not enough to even light up the dash?...

2) If the alternator wasn't working, would the battery have 12.38v after 1 hour driving? I think the alternator works.

3) If the battery and alternator work, would it be a fuse that blew up and is blocking power to run through the electrical system?

Any light cast in this mess would be much appreciated!

Cheers,

Romain

Have you checked that the connections to the battery and chassis ground are all clean, free of corrosion and tight? This sounds like a possible connection issue.

47 minutes ago, rdcteodosio said:

The battery seems to be ok as it managed to keep a high enough voltage over 2 days unless 12.38V is not enough

That is actually a little low, but not enough to cause problems.

I would be suspecting that the battery has a faulty cell that is collapsing while under load.

With the engine running at a fast idle measure the voltage across the battery terminals. It should be at least 14.5V if the alternator is charging correctly.

Does sound like a connection issue of some kind - if you’ve got 12V at the battery you should get some life showing electrically before you hit the system with bigger loads such as starting etc 

Or a main fuse gone, worst case being the mega-fuse which is built into the battery positive cable (assuming your model has one)

1 hour ago, unofix said:

I would be suspecting that the battery has a faulty cell that is collapsing while under load.

With the engine running at a fast idle measure the voltage across the battery terminals. It should be at least 14.5V if the alternator is charging correctly.

but would that faulty cell be enough to not even light up the car? Dash lights, tft screen etc? I’ll try measuring the voltage if I manage to jumpstart it again. 
 

1 hour ago, mjt said:

Have you checked that the connections to the battery and chassis ground are all clean, free of corrosion and tight? This sounds like a possible connection issue.

That’s how they look.. I’ve seen a lot worse. I think they are tight but I’ll have a look. 

6 minutes ago, rdcteodosio said:

would that faulty cell be enough to not even light up the car?

On a modern car like your 2020 Focus, as soon as you turn the ignition on it draws 20Amp or even a little more before the current falls back to around 9Amp. It very much depends on how faulty the battery might be.

I see from the photo that the battery appears to be the factory fitted original. If that is the case then it is 4 years old and is very likely at the end of it's life.

Maybe I misunderstood the original post but I thought @rdcteodosio was saying the electrical system was totally dead, no lights, no central locking, before turning on the ignition. That's what made me suggest a connection issue.

Although the battery connection posts look clean in his photo I think it would be worth disconnecting them and cleaning the contact surfaces of posts and clamps and do the same where the negative cable connects to the suspension tower, just as an easy way to eliminate these as possibilities.

Always disconnect the negative connection of the battery first and reconnect it last (sorry if you aleady know that ).

From above, definitely get the battery tested if possible or charge and get it taken to somewhere?

High discharge or Midtronics at dealer (or both to rule out different faults?) then if totally dead before ignition on check heavy leads and body/engine strap  then big fuses (check the handbook) as suggested?
One intermittent faulty cell can do it - batteries are like people, they have multiple failure modes so if you test for one factor you may not find the actual problem.
If you do the basics above then come back with exactly the state of play i.e. what happens ignition off, then on then try to start etc?

28 minutes ago, mjt said:

Maybe I misunderstood the original post but I thought @rdcteodosio was saying the electrical system was totally dead, no lights, no central locking, before turning on the ignition. That's what made me suggest a connection issue.

Although the battery connection posts look clean in his photo I think it would be worth disconnecting them and cleaning the contact surfaces of posts and clamps and do the same where the negative cable connects to the suspension tower, just as an easy way to eliminate these as possibilities.

Always disconnect the negative connection of the battery first and reconnect it last (sorry if you aleady know that ).

You understood correctly, there’s no power at all in the car. I can’t even open the boot and the car is opened as it didn’t close when there’s still was a bit of power. I’ll check the connections, what do you use to clean them? 

Maybe try measuring the battery voltage while you get someone to turn the ignition on, or test it yourself once the ignition is on - you can see them if there is a significant voltage drop once the battery is under any sort of load. 
 

Might help rule out or confirm the battery being faulty or not. 

Or if you can get access to a boost charger/power pack and try connecting to the positive terminal once it’s removed from the battery? 
 

May be some issues with the BMS system getting confused so not 100% sure this would work for you, I’ll defer to others who have better knowledge of the later Focus electrical systems here

2 minutes ago, troy45 said:

Or if you can get access to a boost charger/power pack and try connecting to the positive terminal once it’s removed from the battery? 
 

May be some issues with the BMS system getting confused so not 100% sure this would work for you, I’ll defer to others who have better knowledge of the later Focus electrical systems here

Yes I think that’s what I’ll do. I’ll charge my booster power bank and give it a try tomorrow. 
one thing that I remembered as is that even though the auto start/stop is on it never really worked which means the battery would be below 40% from what I read. There’s that battery reset thing I’ll try as well once I’ll get it to start. 

41 minutes ago, rdcteodosio said:

There’s that battery reset thing I’ll try as well once I’ll get it to start. 

NO !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

It is NOT a battery reset 'thing'. The Battery Monitor System is designed only to be reset when a new battery is installed.

Resetting the BMS when the battery is still the old firstly causes the 'days in service' counter to be set back to zero, and secondly the charging algorithm which adapts as the battery gets older will also be reset and the battery will be charged as if it were new.

If no power at all then there's a major battery or heavy duty connection issue Or BIG fuse(s) if it's now impossible to get a known good battery to supply the vehicle?
Regarding cleaning contacts, I always use wire brush (+ hot water to get any flaky corrosion off) then either Vaseline (not normal grease, it's different) or use more modern "dielectric grease"
Unless someone younger and wiser has a better solution? 😉

35 minutes ago, unofix said:

NO !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

It is NOT a battery reset 'thing'. The Battery Monitor System is designed only to be reset when a new battery is installed.

Resetting the BMS when the battery is still the old firstly causes the 'days in service' counter to be set back to zero, and secondly the charging algorithm which adapts as the battery gets older will also be reset and the battery will be charged as if it were new.

🤣

lol… got it. Thats a good one to know if I get a new battery. 

So I replaced the battery last week as per a RAC guy that came to help me start the car.

New battery, fully charged when installed. The car has today done exactly the same thing. I open the doors, sit and push the start button and it just turns off, doesnt even want to start the engine. I figured out something that Im sure I shouldnt do but I did, I opened the  bonnet and scrached the plus lead on the battery with a key, there were some sparks and the lights turned on. I then ran back inside and could start the car.... Had to do it 3 times though for it to work. I checked the battery and its at 12.4v with the car off.

I drove the car quite a few miles over the week so its not that I dont take the care out. It just seems to drain the battery when its off..

Any ideas?....

So "scratchng" the positive terminal fixes the starting - there may be a bad connection there or somewhere else... unless it's a coincidence?

But still looking like a bad connection somewhere for the starting issue and some other drain if the battery loses charge over a few days?

Sounds like the battery terminals are loose or dirty/corroded.

the title should say "Dead" not "Bricked"

Bricked is user instigated death of electronic modules - you have an easily resolved electrical connection issue - not destroyed bootloader firmware

Not a coincidence. I pressed the start button, the car would die, I would then go to the battery and scratch it with a metal part and voila, headlights on everything on.. I had to do it several times though to get the car to start as other times it would just die again.

Tomfocus -> That's my feeling as well.. Im working on it this weekend, hopefully that will be enough.

Botus -> You are entirely correct sir. Though it's not for lack of power as the battery as enough to get the car started... I should say as well, once the car is started I can turn on and off the  auto start-stop option. If I am not mistaken, this option doesnt work if the battery doesnt have enough juice?.. so that would mean the battery is fine. "easily resolved electrical connection issue".. may the gods be on your side 🙏

1 minute ago, rdcteodosio said:

I would then go to the battery and scratch it with a metal part

This was a strange but common fault on a lot of 2019/2020 Focus. I even had it happen with the negative terminal on my own car. The battery posts have a very slight taper like a cone. It seems the battery clamps even when fully loosened were still a little tight. This meant that the clamp did not get fully seated down on the battery post. When the clamp was tightened it tended to cause the battery clamp to slide slightly up the post and make a loose connection.

Take a firm grip of the battery lead and see if you can rotate it around the battery post. If you can then you need to fully loosen the clamp and tap it fully down on the post before re-tightening the clamp.

17 minutes ago, unofix said:

This was a strange but common fault on a lot of 2019/2020 Focus. I even had it happen with the negative terminal on my own car. The battery posts have a very slight taper like a cone. It seems the battery clamps even when fully loosened were still a little tight. This meant that the clamp did not get fully seated down on the battery post. When the clamp was tightened it tended to cause the battery clamp to slide slightly up the post and make a loose connection.

Take a firm grip of the battery lead and see if you can rotate it around the battery post. If you can then you need to fully loosen the clamp and tap it fully down on the post before re-tightening the clamp.

that makes a lot of sense. The battery I got, even though it is the one recommended on the Varta website (Varta EFB 100 Car Battery D54), has a different positive lead that the former one and the clamp doesnt get all the way down. I will definitely check that and clean the clamps properly. 

batteries have two terminals - each as important as the other....

the connections to the battery should be with as big a surface area as can be achieved - loosen the clamp bolts till is spreads open and ensure the clamp always sits lower than the post top - plus sound, clean connections, done up properly tight (lead builds up grey oxidisation - it should look shiny and clean where the terminals sit.  

the wiring to these terminal clamps should be secure not floppy and falling off - if you follow these thick wires to the other ends, its also vital these are clean tight and with zero corrosion - no idea on later ones but the mk 2 splits off and has two earth points - one is always a rusty joke on to paint !!! of one of the strut top bolts

these things will try and move around 300 amps when cranking, which is why they are big large surface area clamps and thick wiring - these experts suggest you can actually pass up to 1000 amps for a split second on only a 33amp/hr battery....  and remember as an example of what 1000 amps can do, IF the voltage was right up there (600v) you can electrocute a human with just 0.1 amps !!!

https://electronics.stackexchange.com/questions/246085/how-many-amps-can-a-car-battery-supply