Sinergex Power Inverters

Submitted: Saturday, Oct 23, 2004 at 16:06

ThreadID: 17244 Views:4321 Replies:3 FollowUps:3

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pauls

Maybe a dumb question, but I have been looking at Sinergex 300W inverters. They claim to be OK with laptops and have regulated modified sine wave not pure sine wave. What are the implications if using a laptop as I thought I read somewhere that you should have pure sine wave for use with laptops.

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Reply By: Glenno - Saturday, Oct 23, 2004 at 17:33

Saturday, Oct 23, 2004 at 17:33

I have the Sinergex modified sine wave. I have used it to charge camera batteries, run soldering irons etc, but not a laptop.

I can vouch for the quality of the unit, im sure someone else can outline their experiences with running a laptop on a modified sinewave inverter.

AnswerID: 81342

Reply By: Mike Harding - Saturday, Oct 23, 2004 at 17:40

Saturday, Oct 23, 2004 at 17:40

Most (all?) notebook computers use a switchmode power supply for their 240V supply. In general switchmode supplies are very tolerant of their input waveform and will operate quite happily from DC, AC and most stuff in-between. "Modified sine wave" is a marketing euphemism for "more or less square" ie. not sine at all. Items most likely to have trouble with it are those with a transformer and a linear power supply (hard to think of many these days) some motors may get a bit upset with it too but most will work. Interestingly I did have some trouble with the new high efficiency lamps and an inverter - two makes were destroyed but the GE products were quite happy with it. Your notebook should be fine with it. 300W is normally much more than a notebook would use - 100W should be plenty, having said that a 300W inverter has much more general use than a 100W unit.

Mike Harding

AnswerID: 81345

Reply By: Wok - Saturday, Oct 23, 2004 at 19:15

Saturday, Oct 23, 2004 at 19:15

Hello Mike,

[quote] 'Items most likely to have trouble with it are those with a transformer and a linear power supply (hard to think of many these days) [unquote]

Could you please provide more information/links that show this?

rgds

AnswerID: 81356

Follow Up By: Mike Harding - Saturday, Oct 23, 2004 at 20:24

Saturday, Oct 23, 2004 at 20:24

Links? No, but you may be able to find them from Google or similar.

Mains transformers are designed to be used with sine waves, ie. a current/voltage waveform which changes at a (fairly) constant rate and is in a constant state of change. A squarish waveform (as produced by most cheap inverters) has a fast change from 0V to Max.V and then sits at Max.V for some time until it rapidly changes to -Max.V etc. The upshot of all this is that what comes out of the secondary of the transformer is nothing like what went into the primary (with a sine wave it would be almost identical in shape but smaller in amplitude) and certainly not much like the linear regulator expects to see - result?: it won't work very well. Without going into a whole lot of complex maths (which I have forgotten :) there isn't really an easier explanation.

If you have specific questions feel free to post or e-mail.

Mike Harding

mike_harding@fastmail.fm

FollowupID: 340590

Follow Up By: Wok - Sunday, Oct 24, 2004 at 06:00

Sunday, Oct 24, 2004 at 06:00

Mike,

The reason I asked is because I have been chasing a 'definitive ie mathematical' explanation for a while.
A practical example [the only one I have found] is a UPS in a home computer setup. eg APC output is 'stepped sine wave'. I would be drawing a long-bow to conclude that ALL switchmode to switchmode connection is acceptable?
The only conclusion I could arrive at is that powering a laptop off an inverter is ok[UPS = inverter + battery] ? I posed this ? to SONY when I needed to take their laptop on the road but I couldn't get a WRITTEN answer if it was acceptable.

Thanks for your information.

Rgds

FollowupID: 340623

Follow Up By: Mike Harding - Sunday, Oct 24, 2004 at 07:18

Sunday, Oct 24, 2004 at 07:18

>The reason I asked is because I have been chasing a 'definitive
>ie mathematical' explanation for a while.

Any decent text on "inductive reactance" will provide the formula and process required to analyse non sinusoidal waveforms but you'll need good maths to understand it.

>I would be drawing a long-bow to conclude that ALL switchmode
>to switchmode connection is acceptable?

You would. There may be input circuitry in some switchmode supplies which would be upset by inverter type waveforms, unlikely but possible.

>I posed this to SONY when I needed to take their laptop on the
>road but I couldn't get a WRITTEN answer if it was acceptable.

They could not really give one because they don't know the exact nature of your inverter and it's output. And once they put in writing that their notebooks can be powered with almost any waveform people will be hooking them up to electric fences and wondering why they blow up.

Mike Harding

FollowupID: 340627