I'm wondering if I can pick your brains to figure out what's going on with my car's battery.

 

My battery went below 10.8v last night, and the car wouldn't start (obviously). I connected my Noco Genius 5 for a couple of hours until I got it up to 11.9v, then started the car and drove around for an hour.

During that drive, I was in the TEST MENU looking at the battery voltage and could see that the alternator was doing its job - charging the battery at around 14v.

Once I got home, I checked the voltage - it was at 12.2v. Went to bed and woke up this morning to find it at 11.9v.

Started the engine, and the TEST MENU still showed the same voltage (11.8 - 11.9). At this point, I'm questioning why it appears the alternator isn't working, as it was last night.

Does anyone know what might be happening here? I replaced the alternator back in 2021, so I'm surprised if it died after only doing 21k miles.

 

Another few things to mention:

On 4th September I had the timing belt, water pump, and serpentine belt replaced by the dealer.

Yesterday, I hardwired my dashcam back in (took it out for a couple of months as I thought I was going to sell the car, but didn't). I used 2 fuse taps in F79 (batt) and F85 (acc), in the correct orientation and with the top fuse (for dashcam) being equal or lower to the bottom fuse (for original fuse)

 

Right after testing to make sure the dashcam worked in normal mode and parking mode, I moved on to plug in my laptop and loaded up Forscan. I connected with Forscan for over 30 minutes with the car in switched mode with the headlights on while waiting for my Forscan extended licence email to come.

After a while of sitting there, I got a warning about a headlight malfunction, followed by service required, chimes and almost every light on the dashboard blinking. I couldn't turn the headlights off and none of the dashboard or SYNC controls were responding. I couldn't even turn the car off with the start button. After about 20 seconds things started responding and I was able to turn it off.

That's when I tried starting the engine... It got about halfway and then immediately shut down, at the same time, the rear brake lights flashed rapidly. Before thinking about the battery voltage, I immediately thought I'd caused a problem with the electronics with my dashcam hardwiring. Tried starting the car again, wouldn't turn over. That's when I knew the battery was dead, and then I did everything as mentioned at the top of this post.

So, could it be an issue with my hardwiring? or is the alternator at fault?

I'll also mention that the dashcam hasn't been plugged in this entire time, so I don't think it's the wiring.

The only other thing I've done is take the front passenger seat out to give me easier access to the passenger fuse box. There's a permanent open circuit, but I don't think that's going to cause any issues either.

 

Sorry for the wall of text. :)

How old is the battery ?

It sounds to me like it has a dead cell.

Battery was replaced in 2020. It is draining very fast from full. Within minutes it dropped by 2% shown in Forscan.

Unplugged the dashcam wires just in case.

Forscan showing another 2% drop in minutes.

While engine running, alt_cur is reading 3A

 

I would get the battery health checked. Worth checking also if you have a guarantee on it as many batteries come with a good length of time on guarantee. Had to get one in January (stop/start type) for my recently parted Fiesta and it came with a 5 year guarantee.

49 minutes ago, BenM91 said:

Battery was replaced in 2020. It is draining very fast from full. Within minutes it dropped by 2% shown in Forscan.

That would confirm my suspicions that the battery has a dead cell. Most, but not all batteries come with a 3 year warranty (some even come with a 5 year). Go to Halfords, or KwikFit and get the battery tested for free. Better if you disconnect it from the car before testing to get a more accurate reading.

Cheers for the invaluable advice, guys. I bought it from Halfords so I'll go back to them. 🙂

My Focus ST has been having battery drain problems.  Took it to the dealers as it is still under warranty, battery OK, charging system OK but battery turns itself off at 49% charge, hence all the problems I have been having with the display not working properly, it doing updates when it shouldn't, auto stop/sstart not working, interior lights not coming an and lots of other things.

Turns out there is a drain in the system which Ford have not yet identified - GARRSP!  This has been going on for years I see from this topic.

Customer service said that there is a fix/update in the system but the dealeer thought it would not work on my car - WHY?  SO they did not apply it!!!!!

Next good news is that updtes are not covered under warranty - but this is not an update as far as I am concerned, it is making the car work properlyu as it should.  I see a battle ahead.

I am now waiting to hear from the dealer to arrange a time for the supposed fix.  They have not rung me back so I am going back to Ford Customer Service to help chivvy them up (polite version of what I was actually about to write)