If the batteries are strandard of the shelf SLA then they must be fitted. If not there is no guarantee thet have been purchased for any particular lift or sole end user.
This is different for bespoke batteries as you say, but again, if not fitted, how is it known if they are intended for a specific end user. The Vat exemption is for a single Chronically sick and Disabled person, if the person is just elderly, VAT is chargeable, but at a reduced rate. Charities often think a Stairlift they are fitting in a stairwell for anyone to use also attracts at a Zero VAT rating.
A problem in this competitive industry is as a supplier, we must purchase and pay HMRC VAT, but then have to Zero Rate our sales.
Less scrupulus may not bother and just look for maximum reveneue available to the to cover their costs with immediate effect as the competitive look to their next VAT quarter for VAT paid.
Not exactly a direct answert to your post Kevin, but a little extra thrown in to the mix for a good healthy discussion.
