13 replies to this topic

[Old Crow]

     While I often see the argument about an inverter being inefficient, I don't get why I should care about that in charging my laptops with a small inverter. I've not had any problem just going ahead and doing it.

 

I've been running my MacBook Pro 13 and my wife's Mac Book Pro 15 off a little $35 150-watt modified-sine-wave inverter plugged in to a 12-volt outlet for several month-long trips per year.  My first MBP13 was a 2009 and prior to that I ran a Dell Inspiron 15 off that same inverter... so I've been doing that at least since 2005.

 

I bought a car-charger cable for that first MBP13 from an Amazon seller and found it would indeed charge but the charge was so slow that I soon went back to the inverter.  I joke that I didn't have time to be that efficient.  I'm sure a current one would be much better at that but it's also pricey and (as I say) I don't see the advantage.

 

The other possible problem with a car-charger cable is the changing standards for cable-ends on the computer side.  My first MBP13 had a MagSafe but my current one has a USB-C (Thunderbolt 3) power connector.  It would be frustrating to buy an expensive car-charger for a MagSafe one only to realize it won't work when you buy your next laptop. 

 

Also- 

 

I know from experience that I can plug both of our laptops into the inverter at the same time and it will charge them both.  If we discharge both laptops deeply and then plug in to charge simultaneously, the inverter will sometimes set off the over-draw alarm. But I've only heard that alarm a few times and it's easily avoided.

 

I know from the power supply markings that my MBP13 draws up to 61 watts and my wife's MBP15 up to 85 watts.  Out of curiosity, I plugged mine in to a Kill-a-Watt meter yesterday to see what I could learn in a brief test as I know the ratings are an "up to" figure.  At first, I saw readings in the 3 to 5 watts range as I worked.  When I'd stop for a bit, it would go to zero (because the battery's full). 

 

I then unplugged it (while still using it) and waited for it to discharge before plugging back in.  At 90 per cent, recharging drew about 28 watts.  At 70 per cent, I saw it climb to 50 watts upon plugging in but drop back to 35 watts very quickly.  At 50 per cent, it again went to 50 watts and then dropped back to 38 watts within a minute.  That was the extent of my brief test so I don't know what it takes to draw the entire 61 watts (or even if my specific build draws that much).

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Edited by Old Crow, 13 August 2019 - 12:22 PM.

[esimmers]

I second Old Crow's experience. Don't waste your money trying to find and use an off-brand 12 volt charger for an Apple laptop that uses a MagSafe connector. They just don't work and (so I've read) can actually harm your laptop. A small inverter that plugs into a 12 volt cigar lighter socket in your car or camper will easily power the 120 volt Apple power supply that comes with your computer.

 

Things are getting better. Newer computers, including Apple laptops, that use a USB-C power connector can be powered directly from a 12-volt source like your battery. Search online for "USB-C car chargers" and you'll see lots of options including chargers that plug into the cigar lighter socket or ones that connect directly to your 12 volt battery.

Edited by esimmers, 12 August 2019 - 11:56 PM.

[Casa Escarlata Robles Too]

I have also used a 150W inverter for years.For all things rechargeable.

Laptop,batteries,phone,portable DVD player.

It seems so simple to me.No battery drain while solar is cooking.

Frank

 

I also use the inverter to run my coffee grinder.

[Stan@FourWheel]

My personal opinion ...  "Go for it".

 

If you have dual batteries and solar on your camper, I can't see any reason you can't recharge a small laptop battery through a small inverter plugged into the 12v socket in your Fleet.

 

I've never had any problems running tv/dvd players on a small 400watt inverter, and running lights, running fan, refrigerators, furnaces, etc. on the camper batteries.

 

Just my personal experience.