Had a relatively nice day today... And I wasn't crazy busy doing something else. So I uncovered the Mustang. I installed the battery again which I removed in November. My question is does everyones battery move left to right approximately 1/4 to 1/2 inch? My battery is flat in the tray. The hold down strap and bolt are in place and the bolt is tight. I double checked everything. Just do not remember it moving before. It is the original battery. Thanks!

 

Should be zero movement of a battery

 

Figured out my issue. Was a simple mistake really. The battery heat shield cannot be installed under the hold down strap. It allows the battery to move. You have to bolt battery down, then put on heat shield. Then install battery cables. Nice and tight now!

 

Good you got it resolved!

 

?? My hold down strap is on the outside of the heat shield and I don't have any side to side movement. I've had my battery out a few times and I've always left the "foam" on the battery when going in and out.
Pic for reference, is this the same as yours?

 

I had to have mine the other way or I could not get the battery to stop moving. It was not much... 1/4 to 1/2 in left and right. I took lots of under hood pictures when I got my car... But none directly of the battery. I could see it in the corner of one picture and it appeared as though the foam was over the strap. That is what gave me the idea to try the other way. If the battery is tight I am sure it does not matter. But I think the way I have it now is factory?...