…can they be used to power a laptop for movies ???

Amazon have some for £20ish ?!?!

Thanks in advance

In theory yes, however in practice, the cheap ones put out “dirty” power which not all laptop chargers will accept – I had one that would happily light a 100W bulb in a light, but the laptop refused to charge at all from it.

not without the engine running

and why not buy a 12v laptop charger insteda of converting 12v to 240v and likely back to 14-18v.

not without the engine running

obviously !

and why not buy a 12v laptop charger insteda of converting 12v to 240v and likely back to 14-18v

???

some thing like that OR just “*insert name of laptop* 12v car charger. ” and do away with all the adaptor.s

You say obviously – but i had to rescue a chap on a campsite in Dumfries who plugged an inverter in + some appliance on a campsite and instantly flatted his battery.