I think to fill the space and give you the best usage, you'd end up with
a bank of batteries, and it'll cost a crapton.  I'd love to do this too,
  I have a LiFePO4 battery on my motorcycle
(http://products.batterytender.com/Batteries/120-CCA-Lithium-Engine-Start-Battery.html),
and the equivalent Ah (it's not, but you can run Lithium almost dead
where Lead-Acid doesn't like that) is less than 1/4 of the size.

On 7/14/2017 10:03, Don Hanson wrote:
> Is there an available Lithium battery that fits into the space under the
> driver's seat in our van?
>     One might be far superior to the older generation batteries...Do they
> even make deep cycle lithium battery s?
>     I swapped in a lithium battery to save weight in my track car, did the
> same job at about 3-4lbs that the standard battery (20lbs?) did, and tiny.
> One could probably go 12v refrigeration, more than a day
>

toodle pip,
--
       Dug Smith          | Terry Pratchett: It's almost
(mailto:dug@dugbert.com) |  impossible to ride a rock and roll
(http://www.dugbert.com) |  motorbike and stay on for three verses.