There really isn't a lot we know about Sharinganless Kakashi, but I was always under the impression his chakra reserves were so low because he had a constantly activated sharingan.
I can't make a complete conclusion with such a broken character, who admittedly probably wasn't meant to be given much thought to begin with. For all we know, Kakashi without sharingan could have 10x more chakra, and use techniques to a bigger scale.