Cummins ISX issue

I have an ISX and here’s the problem. It has an automatic shutoff and I think I left it running at the shop one day and it shut off and I forgot to turn off the key. So it sat there with key on and I had to jumpstart it this morning after it had been sitting for at least 10 days. Took a while and when it started I couldn’t give it any throttle and it was belching black smoke. This truck has a complete delete with no DEF or egr valve. I’m thinking the batteries aren’t putting enough amps for it to run right but wondering what you guys thought

 

It’s been running great for over a years since said mods. I’m thinking it’s a battery issue

 

Welded, but it’s weird how it just happened after dead batteries....

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2012. Don’t know which ISX it’s in one of my fleet trucks

 

No codes.....ran fine before batteries went dead