Charging laptop

[RJJ]

Hi folks - can I please ask about charging and the inverter?

My inverter is wired only to work when engine is on. For charging a low-load device like a laptop, I would rather use a device like this

Universal DC vehicle Charger 12-24V for HP Compaq Dell: Amazon.co.uk: Electronics

Assuming the adaptor fits the laptop, am I right in thinking this would take reasonably low load on the 12v circuit? In comparison with running the inverter for a 3-pin plug, which then steps-down again for the the sake of (ultimately) a low voltage need.

I hope ideally to be able to work on the boat at anchor on solar (300w panels) without running the engine; or at least running every other day or so. My energy budget seems to permit this (plus fridge, anchor lights and music) as long as I can fully charge the laptop during daylight hours while still getting a full battery charge.

 

[pvb]

Yes, a car charger is the most efficient solution.

 

[Mistroma]

More efficient but still not 100% (well nothing will be). Remember that it could still be using about 10A if you don't have a newer low power laptop but probably more like 5-7A when charging for quite a few laptops.

It makes more sense to use your laptop on internal battery in the evening and recharge using excess solar. I do that myself. My lead acid batteries are much less efficient than laptop batteries wrt charging.

Downside is that the less I discharge the domestic batteries the less efficient the re-charging becomes. But you want to avoid deep discharges anyway and the laptop still saves some extra discharge.

 

[MarkCX]

I do the same with most of my rechargeable devices. It makes a significant difference when making the most of solar. Most devices don’t taper off charge acceptance the way lead acid batteries do.