Electrical Dilemma

[Mike23864]

Had electrical issues on and off since buying my converted T6 MY 2017.
Thought I had a parasitic drain as starter battery power draining over a couple of days of use

Had an auto electrician come out - no parasitic drain, starter battery ok (new 4 months ago) alternator charging ok. It’s been sat on drive for 3 days after I fully charged it and it’s still at 100%.

However- I take it out for a run and the starter battery drops hugely and I start getting issues with stop/ start and the fuel gauge which fluctuates between empty, off the scale full and 3/4 which is where it should be.

Only fault code relates to oil pressure gauge.

Any ideas chaps?

 

[JOG]

Those are weird symptoms and a bit disappointing that an auto sparky failed to help. Electrics are witchcraft for me….someone who knows more will be along soon

 

[Dellmassive]

Wonder if we have dodgy main conection somewhere.

Corroded cable?

Rubbed through cable?

So issue comes back when driving or vibration..
I'd ask auto electrician to come back and take him for a test drive with his meter connected up.

Did he scan for codes?

What faults were logged?

Can you get voltage readings...

At rest.?
During cranking?
At tick over?
At 2500rpm?

Post some pics so we can see what's what.

 

[oldiebut goodie]

How about:
Old fashioned split charge to a leisure battery.
Absolutely flat and fooked leisure.
The 2 batteries trying to equalize, dragging down starter.

Just a thought due to it draining whilst on a run.

 

[Mike23864]

Thanks all. I’ll run a Carista scan tomorrow and post findings. For now here’s pics of my BM2 and Victron MPPT which shows leisure battery voltage. Thanks again

 

[Pauly]

I would start checking the main negative connections, there is one in front of the battery to the right (behind headlight) and the main one is too the left of the battery and a bit lower down (engine side of the divider)
Corrosion or loose connection here will make strange and sometimes sporadic things happen

 

[Mike23864]

Thanks I will. To help exclude anything associated with the B2B system do I just need to isolate by removing the big in-line fuse on the additional cable going to the starter battery positive?

 

[Murdoch]

Moll battery ?

 

[Mike23864]

It’s a Halfords AGM 80 ah stop start. Fairly new

 

[Dellmassive]

You have a BM2.... Thats great.

Just the one on the starter battery,,?

Can you post BM2 screen shots.

For the last 7 to 14days.

Do one screen shot per day like you did above.

We will then be able to see the alternator charging the battery...

Plus the rate of decay after switch off.

Thanks I will. To help exclude anything associated with the B2B system do I just need to isolate by removing the big in-line fuse on the additional cable going to the starter battery positive?

Yes. Remove that main fuse.

 

[Dellmassive]

For reference here are some BM-2 plots for my Starter battery (using the BM3 app)

..

24 HR slice over various days.

Note my Starter battery drops to a resting voltage of 12.2v.... which is normal for my van. 75Ah Varta AGM. 3.5yrs old.
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[Mike23864]

Thanks @Dellmassive. I am pulling the historical charts but tbh I haven’t used it much over December.

I charged it fully and for the past 2 days it’s been sat on the drive at 100% consistently.

This morning i opened the drivers door, attached Carista to run a scan (didn’t start it) and I got this

 

[Dellmassive]

that looks ok to me . . 12.7 to 12.6 volts over 12hr period.

its not dropping while parked up. . . . ( to indicate a massive problem )

The blip at 10am will be you playing with Carista etc as you unlocked the van and powered up the modules.

all looks normal.

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and shows a good health starter battery voltage . . . much better than mine at 12.2v over night.


...........



now go for a drive and post the BM2 plot later. ( it will show whats going on when the engine is running )



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what was the original complaint? - dead battery / failed to start?

what makes you think you have a problem?


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