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Old 30-08-19, 16:59
Matt_Chambs Matt_Chambs is offline
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Join Date: Aug 2014
Location: Swindon
Posts: 2
Default Inverter or no inverter?


I'm trying to figure out if it's worth fitting an inverter to my leisure battery. It would mainly be for my laptop (20.2 v 4.3 A with 83W power adaptor MacBook)...

I've found a few videos on Youtube with people saying you can get an adaptor that will plug into the 12v socket and convert the 12v supplied by leisure battery to 20v for the laptops, eliminating the need for the inverter. One of the benefits seemingly being that you do without the need to convert 12v to 220v with the inverter (also expensive) and then back to 20v with the laptop power plug...with loss of efficiency.

But I can't seem to find one of these adaptors for my Mac... they all seem to be for Lenovo, Dell, etc...

Any thoughts, ideas?

Thanks in advance to anyone who contributes!

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Old 31-08-19, 06:56
Changa Changa is offline
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Join Date: Apr 2017
Location: Boston Lincolnshire
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T5 Post Icon Re: Inverter or no inverter?

I've considered the same. Have a look here
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Old 31-08-19, 09:24
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Hoovie Hoovie is offline
Want Electrics? Go Wildebus!
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Join Date: Jul 2013
Location: Scottish Borders
Posts: 7,858
Default Re: Inverter or no inverter?

Two options as you have identified.

1) Get a DC-DC Converter

2) Get an Inverter and use your existing power supply

Pros and Cons of each.

Pros: Efficiency - reduces conversion loses going from DC-AC-DC. (Note that there ARE still losses converting from DC-DC though)

Cons: Expense - need to buy a DC-DC converter
Cons: Flexibility - if you change device, you probably need to buy another converter

Pros: Flexibility - you can plug in any 240V AC Device (within power limits) you want using existing AC power block. Change lapop, have two different laptops. Use for other stuff than a laptop. Doesn't matter.
Pros: Expense - once bought, doesn't need changing if devices change

Cons: Efficiency - DC-AC-DC losses higher than DC-DC losses

You can get an Inverter for less money than a pre-packaged DC-DC Converter and that inverter will also work with any laptop, same as your 13A socket at home works with any laptop.
Inverters tend to have around 85% efficiency, so you will use say 15% more battery power compared to a DC-DC Converter while it is plugged in. If you use the inverter when driving to charge the laptop, then that extra use will be made up by the alternator/split charge system.
If you have just one specific need and would be delivered by either an Inverter OR a DC-DC converter, then the DC-DC Converter is the more effective option. If you think is is likely you will need multiple DC-DC converters (more devices, changing devices) then the Inverter can be a better option.

I use both in my Campervan. I have battery chargers for tools, electric blanket, rechargable toothbrush, laptop, plus various other stuff. If I was to get DC-DC converters for, or source DC versions, of all those things it would cost loads of money whereas a single inverter will do the job.
However, I also run an Amazon Echo in the van which stays on 24/7 when I am away. That uses a tiny amount of power and an inverter being on just for that would be incredibly inefficient, so I made a DC-DC Regulator (Converter) for that specific device.

Horses for Courses, but don't dismiss the simple option due to scaremongering tales of inverter inefficiency.
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Old 31-08-19, 10:09
Nafuk Nafuk is offline
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Join Date: Nov 2012
Location: Stoke
Posts: 153
Default Re: Inverter or no inverter?

....going through exactly the same dilemma with Macbook Pro, and ordered something similar to the charger Changa linked to. It did not work, so I am going down the route of a smallish inverter ( I can charge other stuff also).
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Old 04-09-19, 09:47
Matt_Chambs Matt_Chambs is offline
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Join Date: Aug 2014
Location: Swindon
Posts: 2
Default Re: Inverter or no inverter?

Thanks all for your input.

I think I'll go for the inverter, as it looks like it offers more options in the longer term, and also seems like DC-DC converters for a Mac. that actually works seem hard to find.

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