Laptop and Modified Sin Wave Inverter

Submitted: Monday, May 22, 2006 at 14:28
ThreadID: 34132 Views:3082 Replies:13 FollowUps:21
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Hi Again,
Is anyone using a Modified Sin Wave Inverter for charging a Laptop? Ws just wondering if there was any issues as I did not want to fork out the extra $$$$ for Pure Sine Wave as it will probably be used 3 times a year for this purpose and also charging camera batteries and iPod!
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Reply By: ro-dah-o (WA) - Monday, May 22, 2006 at 14:49

Monday, May 22, 2006 at 14:49
yep,

havent noticed any issues. Like you it was the right price. Only use it occasionally, although looking at purchasing a 12V power supply for the laptop. Fairly cheap.

Have used to charge camera etc and they all end up charged, so there cant be too many issues. Im sure that someone will have a clinical answer for the cons of using mod sine.

good luck
AnswerID: 173970

Reply By: Noel W (Qld) - Monday, May 22, 2006 at 15:12

Monday, May 22, 2006 at 15:12
Hi phillowe

I have not been using a modified sinewave inverter but I have been told a pure sine wave is the only way to go to maintain maximum battery life for a laptop (and apparently mobile phones).

I received this information from a 12 volt retailer who made this claim based on his recent experiences and personally, I have no first hand knowledge.

However, laptop batteries are not cheap and premature failure (if due to a modified sine wave) may make it worthwhile spending the extra on a pure sinewave inverter if the primary use is for laptop battery charging purposes ... and ... if you wish to believe the technician I spoke with.

I'm sure others will have some experiences to quote .....
AnswerID: 173975

Follow Up By: V8 Troopie - Tuesday, May 23, 2006 at 00:59

Tuesday, May 23, 2006 at 00:59
Noel, you have been told hogwash by somebody who wants to sell you something more expensive.
For a start, the laptop battery NEVER sees the 240V output of the inverter, its the lappy's power charger that gets hit with the modified sine wave. Most of these do not care a hoot wether its true or modified sinewave at their input. The power pack's output will have the correct voltage to charge the lappy battery.
So, if anything is to suffer from a not perfect sine wave, its the little box in between the inverter and computer.
Hope that makes sense to you.
Klaus
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FollowupID: 430092

Reply By: Footloose - Monday, May 22, 2006 at 15:20

Monday, May 22, 2006 at 15:20
I use one for charging phones, lectric shaver etc. Lappy has the real 12v supply. No ill effects yet.
AnswerID: 173977

Reply By: Jugs - Monday, May 22, 2006 at 15:39

Monday, May 22, 2006 at 15:39
If you are using an inverter to go to 240V AC then the laptop wall power supply which out puts depending on the laptop make ~18V DC (all are DC at the back of the laptop) I can’t see how it could possibly make a difference as the wave is only at the 240V wall power supply unit, its DC at the laptop. Using inverters is a really horrendously in inefficient (read sucks lots of Amps) to go to any DC powered device starting from 12~24V DC battery. But I guess it may be cheaper than the several car kits ipod phone laptop. I suppose it depends on weather battery life or cost is critical factor
AnswerID: 173984

Follow Up By: GaryInOz (Vic) - Monday, May 22, 2006 at 16:09

Monday, May 22, 2006 at 16:09
benefit of multiple 12 volt adapters vs one 240 inverter is if you blow up one adapter it only affects one item. If you blow up your inverter, everything is stuffed....
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FollowupID: 429949

Reply By: Member - Stan (VIC) - Monday, May 22, 2006 at 16:55

Monday, May 22, 2006 at 16:55
I got 400w from the ebay - the same as Jcar sells in their shop and didn't
had any problems at all. I am running it with 4 outlet power board connected
to DVD player for kids, Laptop and charging camera batteries... It has
been in a car for more than a year now, running 24x7...
AnswerID: 174003

Follow Up By: phillowe - Monday, May 22, 2006 at 17:00

Monday, May 22, 2006 at 17:00
Hi Stan,

Is that the Powertech? I have been looking at the 300W.
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Follow Up By: Member - Stan (VIC) - Monday, May 22, 2006 at 19:45

Monday, May 22, 2006 at 19:45
Yep, thats the one.
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FollowupID: 430014

Reply By: Mike Harding - Monday, May 22, 2006 at 17:38

Monday, May 22, 2006 at 17:38
The 240V supply which came with your laptop will be a switch mode PSU. Because of the way switch mode supplies work they are quite happy to operate with a wide variety of input waveform shapes and frequencies and will convert the triangular wave from your 12V to 240V inverter into smooth DC for the laptop. The laptop won't have a clue whether it's running from a 12V or 240V, pure sine wave or triangular (modified sine wave is a marketing term and has no technical value) inverter or the mains or a generator. I ran my Dell notebook from a 300W DSE inverter for ages.

Linear power supplies and things with motors in them may well be upset by triangular wave inverters and should be used with caution. Additionally, for reasons I am not aware of, I have had one make of the new high efficiency lamps blow up when running from my DSE inverter - GE lamps, however, work fine???

Mike Harding
AnswerID: 174014

Follow Up By: phillowe - Monday, May 22, 2006 at 17:44

Monday, May 22, 2006 at 17:44
Thanks Mike,
Good to here I will be fine....Just one question.....By High Efficiancy Globes do you mean the compact flouros????
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FollowupID: 429968

Follow Up By: Mike Harding - Monday, May 22, 2006 at 18:48

Monday, May 22, 2006 at 18:48
This type of thing:
http://www.ecologicalhomes.com.au/EcoNews/econewsAug02.htm#Story%20#4:

I'm currently using the Jaycar 12V ones in a home made lamp holder and they work very well - they draw about 1A so I'm a little skeptical of the 20W claim but they produce adequate light for me:
Site Link

They avoid the loss in the inverter which is significant, about a few hundred milliamps in my DSE unit IIRC. Having said that I quite like my Coleman Dual Fuel lantern, it gives a lovely warm yellow light and is quite sufficient to read by.

Mike Harding
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FollowupID: 429986

Follow Up By: phillowe - Monday, May 22, 2006 at 19:16

Monday, May 22, 2006 at 19:16
Hello Again Mike,
Just got home and plugged my laptop (HP compaq presario) into the inverter (300W Powertech from Jaycar which says for use with laptop...see link) and the inverter buzzed very loudly and I got no voltage to the laptop....however it ran a 200W sander no problem.......any ideas?

Site Link

Thanks Phil
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FollowupID: 429997

Follow Up By: Mike Harding - Monday, May 22, 2006 at 20:13

Monday, May 22, 2006 at 20:13
If your inverter was making "noise" it may be that it thought it was looking at a significant overload. Why this would be I cannot say other than to speculate that HP may have put some protective circuitry into their PSU which goes into conduction mode when confronted with a non sine wave input (why they would do this I cannot imagine?!).

It is also just possible that the load sensing of the inverter is being confused by the HP supply. One thing which may be worth trying is to run the inverter with a load (say a 60W globe) through a power board or adaptor and subsequently plug in the laptop.

In any event - for whatever reason - there does seem to be a problem in this particular case so go carefully – you may be the exception which proves the rule :)

Mike Harding
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FollowupID: 430021

Reply By: Redeye - Monday, May 22, 2006 at 18:04

Monday, May 22, 2006 at 18:04
Hi,

Have run a number of Toshiba PCs on my modified sine wave power supply. Now have an ACER have had no problems. Also use it for Pentax camera, Gamboy, numerous mobiles the list goes on.
If anything was to suffer from a non pure sine wave it would be the power supply supplying the DC voltage and not the end product.

Garry
AnswerID: 174021

Reply By: Derek from Affordable Batteries & Radiators - Monday, May 22, 2006 at 20:36

Monday, May 22, 2006 at 20:36
Hi phil,

Most laptops will charge off a modified sine inverter but I have found that you need a 500w unit for most of them.

I supply 500w units for laptop use because the switch mode chargers supplied with new laptops require a large start up current and the smaller inverters will overload.

Regards Derek.
AnswerID: 174062

Follow Up By: phillowe - Monday, May 22, 2006 at 21:34

Monday, May 22, 2006 at 21:34
Hi Derek,
That did cross my mind....However the inverter does not show fault light which I thought it would do if in overload. Anyway how much for the 500W and can I return it if it will not work?
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FollowupID: 430049

Follow Up By: Mike Harding - Monday, May 22, 2006 at 22:07

Monday, May 22, 2006 at 22:07
Your Jaycar inverter has a surge rating of 1KW - I would be surprised if any laptop computer could exceed that.

Mike Harding
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Follow Up By: Derek from Affordable Batteries & Radiators - Tuesday, May 23, 2006 at 06:56

Tuesday, May 23, 2006 at 06:56
What laptop do you have ? I will do a test here.
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Follow Up By: phillowe - Tuesday, May 23, 2006 at 10:09

Tuesday, May 23, 2006 at 10:09
Hi Derek,
I have a Compaq Presario V2029 (Manufactured by HP the PSU is a HP) just returned the 300W to Jaycar and they said the have had the odd laptop that would not run on "square wave" but interested to see how you go.
Thanks again - Phil
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FollowupID: 430145

Follow Up By: Derek from Affordable Batteries & Radiators - Tuesday, May 23, 2006 at 11:11

Tuesday, May 23, 2006 at 11:11
Hi Phil,

I have just done 2 tests with 2 laptops on 2 inverters.

Inverters are...

Projecta IN600 600w with 1200w surge
Sinergex Purewatts 500w with 1000w surge

Both are modified sine wave.

Laptops tested...

LG LS50
ACER C314XM

Both worked great. I don't have a Hp to test. If you are near a K-Mart they have the Projecta range as well. Give it a go.

If you are in Brisbane pop around and I will test it for you.

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FollowupID: 430171

Follow Up By: Mike Harding - Tuesday, May 23, 2006 at 11:39

Tuesday, May 23, 2006 at 11:39
A quick search of the net does not reveal any problems, the manufacturers of "modified sine wave" inverters I looked at say they are fine with computers and these people are powering a Compaq notebook with a 300W one:
www.tgw.net/sailing/vns4000mi/power.htm

I'll guess that the inrush current into the Compaq switch mode PSU (a normal situation with switch mode supplies) is causing the inverter to become confused, another brand (or maybe another sample of the Jaycar one) should work fine.

Let us know how you go, please.

Mike Harding
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Reply By: Pajman Pete (SA) - Monday, May 22, 2006 at 22:08

Monday, May 22, 2006 at 22:08
Autopro and Jaycar sell a $50 12 volt lappy supply. Ours works fine on two different laptops.

Cheers

Pete
Any mug can be uncomfortable out bush

Member
My Profile  My Blog  My Position  Send Message

AnswerID: 174096

Follow Up By: phillowe - Monday, May 22, 2006 at 22:12

Monday, May 22, 2006 at 22:12
Hi Pete,
I was really hoping to be able to go the inverter path as I have about 6 items that I will not need to buy dc power supplies for nor will I have the issue of all the 12v leads running everywhere!
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FollowupID: 430065

Reply By: Trevor M (SA) - Tuesday, May 23, 2006 at 00:03

Tuesday, May 23, 2006 at 00:03
Hi,

I run an IBM thinkpad in the car. It has a high power drain (7.5 amps). Originally I was using a cheap 150W modified inverter and found the overload going off regularly.(not sure actually whether it was the overload or the low battery warning). It would seem to run the laptop if the battery was charged but didn't have the grunt to run it and charge the battery at the same time (also worse at night when I had the lights on etc and ok while I was motoring but warning would go off when idling at lights etc).

Not sure if it was a co-incidence but my battery pack on the laptop recently died (new one about $100.....no generics would go to 7.5 A). Who knows...could have been due to use in the car in this manner?

I now run a 300W pure sine wave inverter and haven't had any issues. Not sure if it is the extra watts or the pure vs modified that is the issue but I would suggest you are better off spending a bit more than the $40 or so for the cheap 150 Watters. Got the 300W pure for not much over $200.

Hope that helps
Trevor
AnswerID: 174112

Reply By: Member - 'Lucy' - Tuesday, May 23, 2006 at 10:27

Tuesday, May 23, 2006 at 10:27
Phillowe

Go down/to Dick Smiths and get yourself a thing called a KERIO.

I looks like your normal( 230/19v) two leads plus transformer pack that you get with your computer, but in a smaller version.

They are made for 12V source, running of computers.

Most laptops need somewhere around the 18/19v mark at 4.5amps and the KERIO comes into its own as it specificcaly designed for this purpose.

There are surges, spikes, dicky inversions/conversions etc etc etc.

You are in fact protecting an investment of approx $2000 with a $80 item.

AnswerID: 174177

Follow Up By: Moose - Tuesday, May 23, 2006 at 14:12

Tuesday, May 23, 2006 at 14:12
Lucy
Did a Google on Kerio and only found firewall references???
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Follow Up By: Member - 'Lucy' - Tuesday, May 23, 2006 at 15:26

Tuesday, May 23, 2006 at 15:26
This will take you to it.

I got mine three years ago for $87.

Gone up a bit but worth every cent for running Laptops.

Site Link
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FollowupID: 430265

Follow Up By: Member - 'Lucy' - Tuesday, May 23, 2006 at 18:38

Tuesday, May 23, 2006 at 18:38
Ooops! that should read

There are NO surges, spikes, dicky inversions/conversions etc etc etc.
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FollowupID: 430323

Reply By: Mal58 - Tuesday, May 23, 2006 at 12:53

Tuesday, May 23, 2006 at 12:53
Hi phillowe,
My experience with this is different to most others comments in this topic. We have an Acer Laptop that was only 12 months old at the time.

I checked the Laptop charger and based on it's ratings it would be drawing a maximum of 75 watt. (I'm an electronic engineer so I know how to work these things out).

Based on that, I thought, yep a 150 watt modified sine wave inverter will do the job, so of to Jaycar and bought one.

Packed the wife and kids up and off we went. Plugged in the Laptop and the kids were set up watching a DVD.

About an hour later the inverter alarm came on and I duly pulled over. The inverter was too hot to touch so I turned it all off and let it cool down.

It was a hot day, so I thought, that perhaps it had over heated as it was in the sun in the back.

A couple of days later when it was much cooler, I tried it with the Laptop and after an hour it overheated again.

When I got home, I did some basic checks, and found that the Laptop was pulling about 60 watt.

I then loaded up the inverter with a 75 watt globe and let it run for a couple of hours. It was barely warm.

I took the inverter back to Jaycar and told them of the problem. I was advised by the shop assistant that the modified sine wave inverters should not be used with switched mode power supplies such as Laptops.

The reason being (and although I'm an electronic engineer, I'm not sure I understood his explanation), was that the peak current at the switching point of the waveform exceeds the device ratings (the switching transistors in the inverter). He also suggested that it would be "hard" on the Laptop charger.

So after a bit of discussion they took back the modified sine wave inverter and proceeded to offer a pure sinewave one for a small discount on their RRP.

I bought this, somewhat unhappy that I had to pay quite a bit more for the pure sinewave unit, and I was sceptical that it would work.

I subsequently tried it it out with the Laptop. Many hours and DVD's later, the pure sinewave interver gets warm, but does not alarm, so it's OK.

Now about three months later, the Laptop charger stopped working and blew the 240V fuse in the house.

The input side (240V), had gone short circuit.

Now it's only conjecture, but maybe this was a result of the "stress" it was placed under when used with the modified sinewave inverter.

Many people will say that they have had no problems. In my case, perhaps the rating of the inverter was too close to the power being pulled from it by the Laptop when considering the "the peak switching currents". Perhaps a higher wattage unit would have been alright. Don't know.

I'll let you make up your mind.

Cheers,
Mal
AnswerID: 174206

Follow Up By: Mike Harding - Tuesday, May 23, 2006 at 15:37

Tuesday, May 23, 2006 at 15:37
Rather like Greeks and gifts: beware of Jaycar shop assistants bearing electronic advice.

Mike Harding
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Follow Up By: Mal58 - Tuesday, May 23, 2006 at 17:18

Tuesday, May 23, 2006 at 17:18
Mike,
Perhaps I gave the wrong impression, professionally I can design Radio and Messaging systems, but I know nothing about switch mode power supplies and inverters.

So from a technical view point while I did not understand the explanation, that does not mean that it was not true.

The fact of the matter is that the modified sinewave inverter did not work in the intended application. The pure sinewave one does.

My experience is pretty close to that of Trevor M (SA), so I am reasonably confident that I am the right path.

Cheers,
Mal
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FollowupID: 430296

Follow Up By: Mike Harding - Tuesday, May 23, 2006 at 18:31

Tuesday, May 23, 2006 at 18:31
>So from a technical view point while I did not understand the
>explanation, that does not mean that it was not true.

It doesn't mean it was either.

Mike Harding

PS. In between his uni studies in a totally different area from electronics my younger son works for Jaycar - perhaps it was he who gave you that advice? :)

PPS. I'm a little surprised anyone designing modern electronics is not, somewhat, familiar with switch mode PSUs. Can’t remember the last time I did a linear PSU.

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FollowupID: 430319

Reply By: Member - Gomax (VIC) - Tuesday, May 23, 2006 at 19:12

Tuesday, May 23, 2006 at 19:12
Slightly off-topic

If you're running external power source via inverter etc, remove the battery.
The continual discharge/recharge significantly shortens the life of the battery.
AnswerID: 174274

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