Some arcade videogame hardware stored ROM decryption keys in battery-backed memory. When the keys were lost, the board was essentially dead. If you place the battery in the mounting so that the connection is broken if removed your security should be as strong as the encryption you've used. You will however need to design in a way to initialize the keys after installation and regularly service it as the battery loses its charge. If there is a chance the keys could be dumped in-place you have to protect yourself against that, too. See .
-a