Can anyone help me locate the battery in a Nissan Primastar van?

My husband is pretty good with cars/vans, but is struggling to find the battery in his works Nissan Primastar van, can anyone help us?|||under the drivers seat im sure or the passenger one pain in the **** to get to if it has a bulk head you need to remove it be able to fold seat out of the way|||as samjhil says but it may be under a panel inside the back door