For a first i see a great textureer in you my heads were only 3/4 as good as yours when i started ( i tried to make somthing like velis hea dbut with no detail XD WHAT A FAIL I WAS
Duno also you using gimp or paint cause you could use select zone on batteries and then make bottom of them both darker using a select zone on ahlf the battery then using the blend tool or what ever it is with a sarker colo then repat on top witha lighter color to detail a little