Ask the seller if he sealed it.  It came with an auxiliary battery compartment under the driver's seat.  With the seat slid forward, it can be opened, unless some odd modification has been done.

Now, how useful that compartment is is another question.  It is pretty small, and only a limited number of battery sizes will fit.  Some owners have fitted multiple small batteries to best use the space for maximum amp hours.  mcneely

---- Alain Thibault <alainthibault@TELUS.NET> wrote:
> Allo all
> I am new to the list and hunting for a 1986-1991 Vanagon Westfalia. The one I'am looking at is in excellent condition with low mileage, but it seems that there is no accessible compartment for the aux battery under the driver seat. The owner tells me it is sealed??? Is it possible that the 1986 camper is not coming without a space for an aux battery? Thanks for your help...
>
> Sent from my iPad 2

--
David McNeely