Nuevo battery fitting

My nuevo L battery is fitted within a plastic box tied down with a single strap , to me it seems a very insecure and unsafe if involved in a accident has anyone had similar concerns and modified the fitting .

Modify the position of the battery instead. 

If it's like ours was, the battery is right in the middle of the underbed storage area . . . in the daftest possible place.

Move it forward to rest against the wall of the storage area, and it will be far more secure in the event of a prang. Far easier to add an additional restraint in that position, and it leaves the storage area as open and unobstructed as possible.

It would have to be a horrendous prang to make the battery move on mine. The strap is very substantial, though the screws which secure it are relatively small. However the weight of the battery helps to keep the screws secure. If you aree worried then replace those screws with bolts and penny washers on top of and below the floor.

I agree entirely with you & what others have said, but also, its inside a part of the van that's  'built-in' as it were, & somewhat constrained by the furniture, what REALLY concerns me on mine & many others is the fact that a big heavy lump, the cooker, with a lot of sharp chassis-edges is only held into a flimsy wood battens by 6 little wood screws, & on many vans (mine included) is slap-bang on the centreline, & in a head-on, it will easily break free & become a missile by hurtling down the isle towards the front with nothing in the way to stop it.
I've even considered making up & bolting a wire-strap to the cooker & coach-screwing it to the bike-rack reinforcing block, might not completely stop it, but it must help slowing it down.

I have mentioned before the batteries under the drivers seat were not fastened down when we bought the Rienza.  I couldn’t get an original Ford clamp so I used a tension lock strap with bolt down cleats at both ends. 
The leisure battery under the passenger seat was not fastened down and the terminals were exposed. There was nothing to stop it from lifting and shorting on the seat base swivel. Again I secured it the same way and fitted covers on the terminals. When I lifted the seat to sort the wiring I found the terminal covers behind the battery.
Considering the weight and fire risk from insecure batteries some fittings leave a lot to be desired.
I remember a Granada with an insecure battery that bounced up and shorted on the underside of the bonnet. The battery blew itself to pieces and it blistered the paint on the bonnet. In another indecent some one dropped a bonnet stay across a battery. He was lucky to be able to grab the stay before the battery blew up.If that happened inside a motorhome it could be nasty.
I know vehicle designers fit more vehicle batteries inside especially vans but I liked the idea of the batteries being under bonnet on our Duetto. An overcharging battery is not a smell you want in a living area. 
As you may have noticed this and insecure items in vehicles is my pet hate. I have seen the end results after a collision.