My original foams have turned to dust on the inside of my battery cover. Is there anything sold on the market i can use to replace them?

Now that is a nice question !

strips of draught excluder will do the job 

or if you want to try something a little more original you could use mould proof insulation like the ones they use on large piping.

http://REPLACEMENT ERROR/topic...ery-compartment-foam

Pay special attention to Deliverance's suggestion in the link above

 aye i remember that brutus