E70 Voltage issue

[Black-Forest]

I was attempting to jump an 07’ 4.8 I had my code reader hooked up at the time as I wanted to see if there were any pre-existing codes in the modules. I noticed with the jumpers hooked up and electrical donar vehicle running all I was seeing on my code reader as far as voltage was sub 12 volts 11.65 to be exact. I was surprised I didn’t see 13.5 plus. I jumped using the terminals under the hood. As I did not have a volt meter with me I was unable to confirm how much current was getting to the battery. Although after looking at the electrical diagram I don’t see any reason there shouldn’t be the 13 plus volts getting to the battery. Any reason there wouldn’t be 13 or so volts seen at or by the DME? I did check connections at the battery and connections tight and clean. I did attempt a start but engine turned over very slowly no start. Thinking IBS or poor ground perhaps? Thank you for any guidance.