Voltage

[Broadleybenz]

I’ve got a electrical nightmare with the car it’s a e320 cdi
A lot of people were convinced it’s the batteries
So, main battery reads 13.76v when running but car cut out and couldn’t get started again so the aux battery was reading 12.93v whilst ignition off,
Does this sound correct?

 

[John]

Sounds a bit low to me.

This was my previous experience with my W211 (albeit E55K):

W211 Stero, indicators, lights, parking sensors etc.. | Electronics and Audio

It could be the batteries or you alternator.

How old are your batteries do you know?

 

[Broadleybenz]

Sounds a bit low to me.

This was my previous experience with my W211 (albeit E55K):

W211 Stero, indicators, lights, parking sensors etc.. | Electronics and Audio

It could be the batteries or you alternator.

How old are your batteries do you know?

I have no idea how old they are tbh with you, recently bought the car
So I need to figure out why it’s doing this.
It’s a nightmare I can’t use it.
Most times it won’t even crank over
Sometime it does but cuts out
Very rarely starts and stays started
It’s torture

 

[AMGeed]

I would check the power to the starter motor, and the earth, if its intermittently starting.
Could simply be a loose connection.

 

[Broadleybenz]

I would check the power to the starter motor, and the earth, if its intermittently starting.
Could simply be a loose connection.

I also get no glow plug light most of the time, and couple of faults pop is abs and esp fault but when car starts if it starts they go away

 

[Fastard]

Have you tried charging the battery ?

 

[markjay]

You should get 14.4-14.7v with the engine running, and 12.4-12.7v with the ignition switched off.

And you should be measuring the starter battery.

 

[wrdcc01]

What is the main battery voltage with the ignition off? Check the ECU connectors for corrosion, check main earth from battery to body and engine.

 

[Broadleybenz]

What is the main battery voltage with the ignition off? Check the ECU connectors for corrosion, check main earth from battery to body and engine.

Thanks for reply
I get 12.43 volts with ignition off
And 13.76 on
Ecu connectors as in the plugs ? Or further down? It’s driving me mad honestly

 

[Broadleybenz]

Have you tried charging the battery ?

Had jump leads on it from my discovery but havnt charged it now
I’m just wondering would this actualy cause the issues I’m having and making no glow plug light and cutting out

 

[chic0821]

I think I put this in before about voltages

 

[markjay]

Thanks for reply
I get 12.43 volts with ignition off
And 13.76 on
Ecu connectors as in the plugs ? Or further down? It’s driving me mad honestly

12.43v with ignition off is fine (80% charged).

13.76v with engine running is low - your alternator or voltage regulator may have a problem.

But neither explain why the car wouldn't crank.

I think you'll need to have the fault codes read by STAR (or iCarsoft).

 

[Petrol Pete]

I have no idea how old they are tbh with you, recently bought the car
So I need to figure out why it’s doing this.
It’s a nightmare I can’t use it.
Most times it won’t even crank over
Sometime it does but cuts out
Very rarely starts and stays started
It’s torture

The mnf date of the battery is often stamped on the battery posts or elsewhere on the battery itself , not massively relevant , new(ish) batteries can still fail.

example one post will have '07' stamped on it , the other '15' . The battery was made July 2015

 

[Broadleybenz]

Aux battery was reading 12.56 v whilst running but then it cut out

 

[wrdcc01]

OK sounds like the batteries are fine. There may be some voltage drop between the alternator and the main battery as the output is a wee bit low. The intermittent no crank could also be a bad connection at the battery along with the alternator. Just to eliminate some main things I would remove clean and tighten all the battery terminal wires and check the earth to body and engine strap.

 

[GeorgeR]

I’ve got a electrical nightmare with the car it’s a e320 cdi
A lot of people were convinced it’s the batteries
So, main battery reads 13.76v when running but car cut out and couldn’t get started again so the aux battery was reading 12.93v whilst ignition off,
Does this sound correct?

See the correct and incorrect readings for the AUX battery here.

AUX battery - testing replacing | Parts, Maintenance & Servicing

I have spent some time testing and finally replacing the AUX battery. Let me share the knowledge here, it may help others. Nearly all MB cars manufactured in the last 10-15 have AUX battery. (So the hybrid models have 3 batteries in total, while the regular ones have two.) It is a small, 10-15...

forums.mbclub.co.uk

I tried to explain the concept of self-testing and trickle charging of the batteries here.