Inverter

Submitted: Friday, Jan 19, 2007 at 21:06

ThreadID: 41409 Views:2590 Replies:8 FollowUps:17

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zedd

Hi,
I want to use and re-charge an IBM laptop from an inverter. I realise that a pure sine wave inverter will do the job. I was looking at a 150 watt as we don't have a lot of electricals to run from it. The only thing we may occasionally need it for is an electric frypan, recharging my camera battery pack and a heater on cold nights. Will this wattage be enough? Also I realise the difference between a pure sine wave and a modified sine wave. I decided with the cost of laptops it was better to go with the pure sine wave. But I have just read an article about a square wave inverter - what the hell is that?
Zedd

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Reply By: Andrew from Vivid Adventures - Friday, Jan 19, 2007 at 21:13

Friday, Jan 19, 2007 at 21:13

heater and frypan ...

well electric frypans can be 2400 Watt ... I've never seen any as low as 150W ... and as for heater ... well you could be waiting a long time for a 150W heater to warm you up ...

Think how much heat you get from two 75W incandescent globes ...

Cheers
Andrew who wouldn't want to be waiting for Zedd to cook dinner on the inverter.

AnswerID: 216524

Follow Up By: zedd - Friday, Jan 19, 2007 at 22:09

Friday, Jan 19, 2007 at 22:09

Andrew,
How many watts would I need to run the fry pan? We can always cook the roast it in the dutch oven - cheaper and quicker according to your news.

I thought it would take less than an electric drill and washing machine (500watts), but perhaps I'm wrong. I read in the archives that one guy ran his washing machine, drill and TV off a 500w inverter. Not all at the same time obviously.

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Follow Up By: Andrew from Vivid Adventures - Friday, Jan 19, 2007 at 22:24

Friday, Jan 19, 2007 at 22:24

Depends on the frypan - they will specify the required watts ... but usually small ones are 1500+ I think.

Dutch oven sounds much more feasible.

Electric drills and washing machines won't run on 150W inverter though.

I run a 600W inverter - Pure Sine Wave.

I run a laptop for moving map, AA and camera battery chargers, Sat and mobile phone chargers and a big laptop for photo storage and viewing.

Usually only a few of these at a time, but I think they could all work if I was prepared to put enough power boards in the back of the car (I have one permanently mounted on the inverter, the 4 plugs of which usually suffice).

I have also run the 12V drill recharger, the soldering iron, 240V drill when too lazy to drag an extension cord outside, and sundry other things.

I hope that helps
Andrew.

FollowupID: 476942

Follow Up By: zedd - Friday, Jan 19, 2007 at 22:34

Friday, Jan 19, 2007 at 22:34

Thanks Andrew,
Looks as if I'm going to have to buy a stronger inverter. I notice you mentioned a 600 watt inverter. Most of the ones I have researched go up in increments of 150, 300, 500, 1000 wattts. Can I ask the brand of your inverter? And possibly cost?
Zedd

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Follow Up By: zedd - Friday, Jan 19, 2007 at 22:39

Friday, Jan 19, 2007 at 22:39

I think I'll save the heater and frypan for camping sites with power. The dutch oven and an extra blanket and socks sound right for cold nites in the outback. I think you have the right idea about chargers.
Ta
Zedd

FollowupID: 476951

Reply By: obee - Friday, Jan 19, 2007 at 21:50

Friday, Jan 19, 2007 at 21:50

HI zedd

I used a square wave 120 watt inverter to charge my laptop and keep it running while travelling (moving map program) and it was the ancient inverter that died in the end. The charger was fine. The tech (computer Q&A) writer Skarbek who writes for the SMH recommends a square wave no probs. (150 watt for laptop charger) They are heaps cheaper than sine wave.

A square wave/sine wave refers to the shape of the ac current in graphic presentation. A sine wave is what you you get on the house supply cos the dynamo back at the power station is a field winding revolving past an array of magnets. As the field approaches and leaves the proximity of the magnets, it produces current first in one direction and then in the other. Its a wavy line but follows a mathematical curve that can be expressed in terms of sine or cosine.

A square wave is like switching a dc current back and forth to get the alternating effect but it is sudden and when drawn on a graph it is with straight lines with right angles. The battery charger on your laptop rectifies the current into choppy one direction dc and I dont think matters cos the battery will act like a capacitor and smooth out the current before it leaves the computer side.

AC electric motors as in a fridge or or drill are more efficient with sine wave or may not even work with square wave. They absorb the energy good cos they mirror the motion of the aforementioned dynamo.

Some of the square wave jobs call themselves modified sine wave and ask for a bit more money but they should be called modified square wave cos they try to make the wave a bit more like a sine wave without really getting there. So they say anyway.

Sorry I cant explain it better. I am going to fit another one and I will put it in the engine bay where it is not really recomended cos of the heat in there but I will find out if it stuffs up. I can do without too many devices in the cab all at once trying to get charged and run things off the dc. .

You will probably run yours from the cig lighter socket like I did last time. I ran the uhf and the laptop at the same time but the laptop needed to start off with a good charge cos it started to run down towards evening despite the inverter pumping away. Like I said the inverter was ancient and hand built. These days they have ic chips to make them work better. Meantime see if you can find out how much current your charger will pull and match it with your choice of inverter and give some margin. Oh, and getting too big an inverter for your needs will only drain the car battery more when the motor is off so they say. But no matter if you only use it while the motor is running.

Try googling around for more info and ask at the shop where they sell them. I wouldn't want to bum steer you because I dont really know your requirements and I am not a techie but just a one time amateur radio person qualified in basic electronics.

cya

Owen

AnswerID: 216528

Follow Up By: Member - Alastair D (NSW) - Saturday, Jan 20, 2007 at 06:18

Saturday, Jan 20, 2007 at 06:18

Owen,
I would seriously think twice about putting the inverter in the engine bay not only because of the heat and the high likelihood that it will fail but this means your are running 240v wiring around the vehicle. What about going through water even a big puddle can send water around the engine bay - water & 12v no dramas, water and 240v = serious potential for someone to get hurt.

Just my thought - keep the inverter in the cab and as high as possible.

alastair

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Follow Up By: obee - Saturday, Jan 20, 2007 at 11:17

Saturday, Jan 20, 2007 at 11:17

I dont run my extension leads through water or in the rain around the house and wouldnt take my inverter into a deep creek switched on either. Even if there was a short powerful enough to induce a current in the car body, where would it be going except back to its source, the inverter. It would fail. Current needs a path. Ever wonder why birds can sit on high tension wires?

The inverter generates heat and needs to dissipate such but I doubt the engine bay environment would be hot enough to create a prob. Soon find out tho.

Owen

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Follow Up By: Andrew from Vivid Adventures - Saturday, Jan 20, 2007 at 11:33

Saturday, Jan 20, 2007 at 11:33

The inverter does generate heat, but only depending on how much is hanging off it.

Inverters are not intended for the harsh environment under the bonnet - if you don't believe under the bonnet is bloody hot and extreme, including wet at times (not just when you're going into a creek), you have not paid much attention to the situation under there. Bonnet temperatures are 100 degrees C plus. Only military grade inverters you would pay a bucketload for would be designed for those conditions.

Inverters - particularly pure sine wave inverters are instruments ... with electronics, and in their case with 240V ... for sure, you should seriously disconnect it when you're at risk of going into water, but the same should be done if you have it in the cab. Sure, current needs a path, but only a path to earth for 240V AC and the potential for someone crawling under the bonnet with a spanner accidentally tripping something off scares the bejesus outa me.

Cheers
Andrew.

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Reply By: Derek from Affordable Batteries & Radiators - Friday, Jan 19, 2007 at 22:02

Friday, Jan 19, 2007 at 22:02

This is our basic range.

No fry pans.

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Reply By: Willem - Friday, Jan 19, 2007 at 22:08

Friday, Jan 19, 2007 at 22:08

My 150 Watt Pure Sinewave inverter is not strong enought to power my Notebook. I have burnt out 2 capacitors running the laptop whilst using moving map. The 150W is OK for charging batteries and a night light but thats about it. I would go for a minimum 300watt inverter.

Cheers

AnswerID: 216532

Follow Up By: Member - Andrew (QLD) - Friday, Jan 19, 2007 at 22:43

Friday, Jan 19, 2007 at 22:43

Wow......my notebook is high-end and it only has a 90w charger (as well as a 12v/240v 65w charger). I take it the problem is with the brand of inverter? :-)

Andrew

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Follow Up By: Member - JohnR (Vic)&Moses - Saturday, Jan 20, 2007 at 06:25

Saturday, Jan 20, 2007 at 06:25

Bro, I have a 150w inverter and it is heaps to power my laptop which draws 70w. I guess it s a bit dependent ont the fuguring of the provider of the laptop and the inverter manufacturer...

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Follow Up By: Willem - Saturday, Jan 20, 2007 at 08:04

Saturday, Jan 20, 2007 at 08:04

Fellas

My Pioneer Notebook(Australian generic) draws 90Watt and my Inverter is a Powertech bought from Jaycar. Not sure about the finer intricasies of the electronics but the Notebook has power surges and this has resulted in the capacitors melting. I now use a Kerio DC Charger when using Moving Map out bush and that seems to work well. I bought all of this gear in 2002 and had a failure in 2003 and again in 2006. Luckily I have a mate who is wise-up on electronics and have had the repairs done for nix. The capacitors cost $1.30 each if you know where to shop.

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Follow Up By: pjchris - Saturday, Jan 20, 2007 at 23:01

Saturday, Jan 20, 2007 at 23:01

Quote "power surges and this has resulted in the capacitors melting"

This is exactly what can happen if using a square wave or modified sine inverter. because the voltage switches suddenly from -240 to +240 on a square wave this causes huge inrush currents into the capacitors on the rectifier in the laptop power supply which can in extreme cases melt them but will more likely cause swelling and leakage followed by failure.

I'm fairly sure, therefor, that your powertech is an old square wave (They don't seem to sell these anymore) or a modified Sine

Peter

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Follow Up By: Willem - Sunday, Jan 21, 2007 at 09:21

Sunday, Jan 21, 2007 at 09:21

Well my Inverter has 150W Pure Sinewave Inverter embossed on the upside of the unit.....................unless ofcourse someone made a mistake at the factory...'tis not improbable.

One would probably need some fancy equipment to test it?

Cheers

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Follow Up By: pjchris - Sunday, Jan 21, 2007 at 13:28

Sunday, Jan 21, 2007 at 13:28

Just a CRO (Cathode Ray Oscilloscope).

Display the output waveform while under load.

If it is a pure Sinewave then it should not be melting capacitors..assuming it is outputting 240V and not a much higher amount (or just more than the laptop supply can handle, I have seen many that only want 230V).

Peter

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Reply By: zedd - Friday, Jan 19, 2007 at 22:16

Friday, Jan 19, 2007 at 22:16

Hi,
Have you since upgraded to a stronger inverter and if so has your problem been overcome? Can I ask what brand inverter you bought at 150 watt and if you have bought a 300 watt how is it now going?
Zedd

AnswerID: 216537

Reply By: Member - John and Val W (ACT) - Friday, Jan 19, 2007 at 22:31

Friday, Jan 19, 2007 at 22:31

Zedd,

Suggest get a car power supply for your laptop and forget the inverter. Likewise you should be able to find a car charger for your camera battery. (Do a search on ebay to check for their existence). Frypans and heaters - forget it - these will require at least 1200 watts and probably double that. Not only is that a seriously big and expensive inverter, but you will require some serious battery power. A big (100 amphour) battery would die under this load, but in any case, holds only enough energy for a few minutes at this rate of discharge.

Sorry - not a good idea!!!!! The laptop and camera are easy and you should be able to find suitable 12 volt power supplies for both.

John

J and V
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Follow Up By: obee - Saturday, Jan 20, 2007 at 20:59

Saturday, Jan 20, 2007 at 20:59

hi

12 volt chargers for laptops are reputedly expensive. They only have to invert to the voltage that the battery requires but they are of limited production runs and only suited to the laptop. I reckon if money not an issue then its the best way to go.

Owen

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Follow Up By: Member - John and Val W (ACT) - Sunday, Jan 21, 2007 at 07:47

Sunday, Jan 21, 2007 at 07:47

They can be expensive, but a multivoltage laptop power supply with 12V input from Jaycar will cost less than $50. These are not uncommon (check out ebay to see a big range). I've used the Jaycar one for years with no trouble. At this sort of price, the inverter option looks expensive!

John

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Follow Up By: obee - Monday, Jan 22, 2007 at 09:57

Monday, Jan 22, 2007 at 09:57

Thanks John. At that rate I take back anything I ever said about inverters and I will go for the multivoltage. Has to be better than pushing the volts up to 240 only to drop them again.

Owen

FollowupID: 477426

Follow Up By: Member - John and Val W (ACT) - Monday, Jan 22, 2007 at 11:10

Monday, Jan 22, 2007 at 11:10

Obee - definitely the way to go!! Do a search on ebay and you will find many sellers of exactly the multivoltage unit Jaycar is offering..... and at lower prices. That's a good place to find a charger for camera batteries too. Even if you're reluctant to buy there, it's an excellent catalogue to browse and then buy elsewhere.

John

J and V
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Reply By: Dave & Shelley (NT) - Saturday, Jan 20, 2007 at 01:23

Saturday, Jan 20, 2007 at 01:23

Hi Zedd,

We have a 600W inverter and it charges up our laptop, phone and lanterns. I wouldn't go any smaller as it is amazing what new toys you buy. They are getting smaller and cheaper. I bought mine from JAYCO for $179.

Happy hunting

Dave

AnswerID: 216576

Reply By: T-Ribby - Saturday, Jan 20, 2007 at 18:02

Saturday, Jan 20, 2007 at 18:02

On the subject of 240v and safety issues (I have a 600w inverter that hasn't been used yet)
Is an RCD required between the inverter outlet and the device?
T.R.

AnswerID: 216687