I have been done a lot of research and reading the last few days to figure out how I can solve my problem.  Finally I ended up at the following page about DC Motors.  See DC-Motors.

There is a part about noise caused by the DC motors.  To isolate both circuits (Raspberry Pi linked/Battery holder linked (l298n->DC-motor))  I have to use an opto isolator (opto coupler).  I did some further investigation and yes, that’s the way I wanna go.  It explains the issue that I have.  So I immediately decided to buy a couple of those opto isolators(4n35 FSC Optocoupler) on EBAY.  I can’t wait to get to work but I’ll have to work delivery which will take a few weeks :-(.  The opto couplers are on their way from China.