I just ordered leisure battery 100 Amps and a charge relay for my van. It's not a campervan, mostly work based van. I need the second battery for laptop mostly. Now, what adapter to use to connect the laptop to the battery? Apparently classical inverters are not very efficient as the current has to be transformed twice, from 12V to 220v and back to the laptop input standard. But little do I know. I never tried it before. Another option would be to convert from 12v straight to laptop via a dc to dc converter Is this a better option? I can charge my laptop from the cigar socket so thinking as well about just buying a simplified adaptop for a fiver that will simply take the current from the leads of leisure battery, and to which I can connect my laptop charger. What the best option would be here? Thanks