Maybe this line:
current = ((bmestat | grep "battery current") | awk '{print $3}' )
is too complicated for someone like me, who knows very little about sh or python.
But maybe split the job up into 3 smaller pieces would be easier:

#!/bin/sh
#Place the output of bmestat into string bmestring
bmestring = bmestat

#Extract the 'battery current' element out of the string in bmestring
element = ($bmestring | grep "battery current")

#Extract the numeric value out of element
current = ($element | awk '{prit $3}')
echo -n $current

Now you can see my lack of knowledge.
Maybe it would be easier in python.
Can someone please help put me out of my misery with this?
Thanks