How to stop the chassis cross member breaking??

[Mpett1979]

Hi,

My nephew's chassis cross member keeps breaking as a result of the battery moving forward and backwards in the chassis battery tray.

I've put cardboard and some foam in there to try and help. It the second one has just broken. My next ideas was to use some denser foam perhaps neoprene or to put a small amount of Velcro onto the base of the battery tray and onto the battery, thereby using the shear fore strength of Velcro to hold it stably.

All ideas welcomed.
Cheers,
Martin