Inverter for Macbook

[EngBrian]

I am purchasing a macbook soon but I am going to start collecting accessories now. One of the things I am in the market for is an inverter for the car.

My question to someone who has more electronics knowledge than me is what can be used that doesn't fry a laptop. Most of the ones I have seen in store use a "modified sine wave" or a PWM (pulse width modulation) sine wave. I just wondered if a synthetic sine wave would damage the PS in the laptop or the power brick for that matter?

Also if anyone could recommend one that will work or has worked for you without incident that would be great. I know of some people who used one and the inverter would stop working after 1 hour because it overheated from all the conversion losses and it would need to cool off before working again. Definitely want to avoid that but it is obviously impossible to tell from the packaging if this would happen. I need real world experience from someone.

Thanks in advance.

 

[johnee]

How much are you willing to spend? I haven't researched inverters, but I have used one for dvd players, etc.

A pulse width modulated power supply will not hurt your mac because the mac's power converter has a full bridge wave rectifier, which conducts on both positive and negative sides of the AC source. The fact is the diodes in this rectifier will simply conduct more than usual. After the fwb rectifier, there is a large capacitor to smooth out the DC signal and route AC currents to ground.

The first concern you should have is if the inverter provides enough power to your mac power supply. The inverter should provide at least 100W.

But the more you spend, the better the inverter, not just in quality of signal, but consistency and reliability. The second concern is power fluctuation and recovery time of the inverter. You want one that delivers consistent power.

 

[EngBrian]

How much are you willing to spend? I haven't researched inverters, but I have used one for dvd players, etc.

I guess I was looking in the <$50 (CAD) range. If that is a reasonable number

A pulse width modulated power supply will not hurt your mac because the mac's power converter has a full bridge wave rectifier, which conducts on both positive and negative sides of the AC source. The fact is the diodes in this rectifier will simply conduct more than usual. After the fwb rectifier, there is a large capacitor to smooth out the DC signal and route AC currents to ground.

Well sounds like you know what you are talking about so that is good. Just in terms of products on the market...Is a "modified sine wave" the same as PWM?

The first concern you should have is if the inverter provides enough power to your mac power supply. The inverter should provide at least 100W.

So even if the macbook is rated to draw 65 watts a 75 watt wouldn't cut it, for instance?

 

[johnee]

I guess I was looking in the <$50 (CAD) range. If that is a reasonable number




Well sounds like you know what you are talking about so that is good. Just in terms of products on the market...Is a "modified sine wave" the same as PWM?




So even if the macbook is rated to draw 65 watts a 75 watt wouldn't cut it, for instance?

Check this out :
http://www.powerstream.com/inFAQ.htm

Also see this video. They suggest using a true sine wave inverter for laptops.
http://blog.outsidesupply.com/inver...true-sine-wave-versus-modified-sine-wave.html

I would suggest an inverter on the larger size because it will have a better recovery time (the time it takes to supply a larger current from a low current state).

Also check out wikipedia.

Not trying to blow you off, but i'm a computer engineer, not a power engineer, and not having worked in this area or researched it enough, I don't want to give you wrong/bad advice.

EDIT : Found this
It's a bit more than you want to spend, but it looks like it would be what you need.

 

[skye12]

Costco sometimes has good deals on cheap inverters...

 

[EngBrian]

Check this out :

Not trying to blow you off, but i'm a computer engineer, not a power engineer, and not having worked in this area or researched it enough, I don't want to give you wrong/bad advice.

Thanks for the links. I definitely understand you not wanting to overstep your training. Being on the mech side of things we only have one power related course which is just about enough to know the difference between AC and DC haha.

Anyway thanks for the info.

 

[EngBrian]

Costco sometimes has good deals on cheap inverters...

Never got a costco membership so unfortunately I can't take advantage of the services there. Thanks for the help though.

 

[steevzie]

i recently replaced my macbook screen since the other screen was broken. i did it myself, but when i powered it back on the screen was visible but the backlight was not functioning. I checked all the wires and everything was good but yet still not backlight. So i did some research and ordered a new inverter. I got the inverter in the mail, replaced it and yet my screen is still the same, black. The screen is used, but tested (apparently) so now i dont know what to do. Is it possible the inverter i received in the mail is faulty since it wasnt packaged that well and may have been shorted due to static? Or is the plastic wrapping on the inverter good enough to prevent it from shorting? Or what do you think at all? Input would be greatly appreciated.