Battery relocation- Does anyone know of an actual hydrogen sulfide explosion incident?

I have a customer with trunk mounted battery and fuel pump. I dislike both. Relays in trunk,trunk light make it a high risk. Its coming for a fall project, think i will try to convince him that original mounting locations are safer.
I knew of a drag car set up this way. Kid( I personally knew) bought it and drove it on the street. The thing blew up. Killed him. No one is sure exactly how it happened but I have to think it was more gasoline vapor than acid vapor.