Take into consideration that this plane is flying on the limits of opperational lifetime.. and beyond. Their resources actually expired in '95 and major overhaul was needed. But as you know, the counry was under sanctions and no such thing was possible. So, high ranking air force officers extended their lifetime by simply signing a document, without ever touching the aircraft. Imagine going to a doctor when you're sick, and he just pronounces you healthy, without even looking at you. Not much use of that.
So, mechanics and pilots adopted ways to squeese as much juice out of their machines as possible. Opperating combat systems on non-combat flights was actually forbiden, and so was unneeded use of afterburner etc..
You can see that big external generator, that is used for startup. I think batteries can also be used, but they are also preserved for emergencies.