Voltage drops below 9V when trying to start

[Mikester349]

Hi all, I have read mods post and any help given will be much appreciated and reciprocated.

For the last couple days I haven't been able to get my 2.0tdi A4 to start. OBD showed no fault codes but battery light is on when turning on the electrics. Noticed the battery was sitting at 12/12.6V idle but dropping right down to 8V when cranking. When hooked up to another vehicle for a jump start to goes up to 13.7V but still drops down to around 9V when attempting to start it just cranks and doesn't ignite. 

Got a replacement battery today but still have the same issues with a brand new battery. I was told this might be a DPF issue or a glow plug issue. What do you all think?

Also within the last couple months I've had the EGR replace and the timing belt and pump replaced too. Screenshot is from a couple days ago, still showing the exact same reading with the new battery.

[Mark M.]

I've seen batteries with a weak cell drop to under 9volts when cranking but if the new battery is ok then I'd wonder if the starter motor is faulty/jamming causing the power drain.

[Mikester349]

Thanks Mark, 

I'll have a look at that tomorrow, also forgot to check the fuses but the starter is turning so I doubt it's the fuse.