Inverter doesn’t seem to be charging laptop?

[chenderson1965]

Hi All,

I have a cheap 500w/1000w pure sine wave inverter (about £15 from Malaysia on eBay) and just tested it on my wife’s, very powerful laptop. The power block says it’ll accept anything from 100-240v, with a maximum draw of 10.4A.

The lights on the inverter illuminate, so there’s definitely power but the indicator on the laptop doesn’t indicate that the battery is charging. The inverter fan pulses in and off and the voltages indicated on the inverter fluctuate. On the dc side from 12.8v down to 9v (the battery is full) and on the AC side from 240 to 110v (and I think I even saw 24v at one point)

I checked that the output socket was live with a different plug and it is.

Connecting and disconnecting whilst watching the current indicator on the control panel suggests a draw of a 2-3 Amps but this fluctuates too. After the control panel and other bits of general drain, that’s very little, possibly no, current being pulled through.

I think an inverter is a pretty simple device so thought a cheap one would be fine. Is it worth spending a bit more to see if that makes a difference - or is it likely to be some other problem?

Thanks
Chris

 

[Raul]

Simple, the load you try to run is greater than the battery can handle, and the voltage crashes. The inverter trips on low voltage cut off, probably 10.5v fixed by manufacturer.
It is possible, that square wave inverter is very inefficient for your laptop power supply.

 

[DavidG58]

I think you said it all at £15

there are some semi decent Plug in inverters but not for £15 although a quick eBay search seems to show there are a lot for that kind of price

 

[chenderson1965]

Simple, the load you try to run is greater than the battery can handle, and the voltage crashes. The inverter trips on low voltage cut off, probably 10.5v fixed by manufacturer.
It is possible, that square wave inverter is very inefficient for your laptop power supply.

It’s a pure sine wave inverter. It seems unlikely to be overload because the max draw should be about 20A (allowing for inverter losses) and the batteries deal with a similar amount when the fridge runs on 12v.

 

[Lenny HB]

I think you have bought a door stop.
A decent 1000 watt pure sine inverter will cost several hundred pounds. I have a cheap £150 1000 watt pure sine inverter, its better than a modified sine inverter but it's not a pure sine wave.

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[David and Sally]

Invert = to turn over. Sounds like you already know you have been

Invest in a good one, why not?

 

[Raul]

It’s a pure sine wave inverter. It seems unlikely to be overload because the max draw should be about 20A (allowing for inverter losses) and the batteries deal with a similar amount when the fridge runs on 12v.

The inverter may be able, but the battery says no.

 

[pappajohn]

I have a cheap 500w/1000w pure sine wave inverter

There's pure sine wave and there's PURE sine wave.
Cheap ones are a type of modified square wave which closely resembles a pure sine wave but still aren't pure.
That's why PURE sine wave inverters aren't cheap.

 

[Richard n Ann]

Hi All,

I have a cheap 500w/1000w pure sine wave inverter (about £15 from Malaysia on eBay) and just tested it on my wife’s, very powerful laptop. The power block says it’ll accept anything from 100-240v, with a maximum draw of 10.4A.

The lights on the inverter illuminate, so there’s definitely power but the indicator on the laptop doesn’t indicate that the battery is charging. The inverter fan pulses in and off and the voltages indicated on the inverter fluctuate. On the dc side from 12.8v down to 9v (the battery is full) and on the AC side from 240 to 110v (and I think I even saw 24v at one point)

I checked that the output socket was live with a different plug and it is.

Connecting and disconnecting whilst watching the current indicator on the control panel suggests a draw of a 2-3 Amps but this fluctuates too. After the control panel and other bits of general drain, that’s very little, possibly no, current being pulled through.

I think an inverter is a pretty simple device so thought a cheap one would be fine. Is it worth spending a bit more to see if that makes a difference - or is it likely to be some other problem?

Thanks
Chris

Just make sure the inverter is plugged in tightly if it's on a cig plug. Or if croc clips make sure they are tight. A sudden current draw can drop the supply voltage

 

[Raul]

It takes a handful of high frequency mosfets, transistors and a transformer to get a decent sine wave. Materials alone will be in excess of 100 quid. Then manufacturing and design it will bring you up close to 250-300 quid for a 500w inverter. The 1000w bit is only for surge of less than 5 seconds.
Also even if inverter can, it needs feeding from healthy source; larger battery bank.

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[Richard n Ann]

I orederd a PSW 1000w Chinese one made by Meind about 5 years ago solely for Ann's hair straightners. It was £67
It works well though, even tried the 700w hair dryer on it briefly and it works

They are more money now, they must have slipped up with the pricing

 

[Lenny HB]

I orederd a PSW 1000w Chinese one made by Meind about 5 years ago solely for Ann's hair straightners. It was £67
It works well though, even tried the 700w hair dryer on it briefly and it works

They are more money now, they must have slipped up with the pricing

Bet if you check it, the output won't be a pure sine.

 

[Richard n Ann]

Bet if you check it, the output won't be a pure sine.

Yes it is, I've got a little LCD oscilloscope. Looked perfect as far as I can tell.

 

[Jimbohorlicks]

It's probably an inverter but doubt it's a pure sine wave inverter for £15.

 

[stevewagner]

I use a 12 volt dc power supply to charge my laptop and it works perfectly.

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[Lenny HB]

Yes it is, I've got a little LCD oscilloscope. Looked perfect as far as I can tell.

Have you checked it under load?

 

[Richard n Ann]

Have you checked it under load?

Errm.. No you might be right then anyway, it works

 

[Langtoftlad]

I use a 12 volt dc power supply to charge my laptop and it works perfectly.

This...
Keep it simple

 

[Neilfg]

We used to charge all manner of stuff using a cheap PSW inverter ( Philips toothbrush, laptop, hair trimmer, shaver, karcher, camera batteries) from Bestek 300w fed by a 12v socket, cost us about 30.00 a couple years sgo., Just looked and 49.99 now

It did a really good job for nearly a year even with the toothbrush which really adoes not like anything but PSW.

We only changed to a much larger, hard wired one inverter as wanted to charge the ebike batteries and that took the Bestek past the 10a limit of a 12v socket. Did try hardwiring the Bestek to the battery but it was very noisy at any draw greater than 90w, so it has now been consigned to the parts drawer.

 

[peterc10]

You don't need an inverter. The laptop uses low voltage DC, so it's daft and wasteful to invert up and then transform back down. Buy a 12v adaptor for it. Just search Amazon with the name and model number of your laptop.

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[jezport]

Hi All,

I have a cheap 500w/1000w pure sine wave inverter (about £15 from Malaysia on eBay) and just tested it on my wife’s, very powerful laptop. The power block says it’ll accept anything from 100-240v, with a maximum draw of 10.4A.

The lights on the inverter illuminate, so there’s definitely power but the indicator on the laptop doesn’t indicate that the battery is charging. The inverter fan pulses in and off and the voltages indicated on the inverter fluctuate. On the dc side from 12.8v down to 9v (the battery is full) and on the AC side from 240 to 110v (and I think I even saw 24v at one point)

I checked that the output socket was live with a different plug and it is.

Connecting and disconnecting whilst watching the current indicator on the control panel suggests a draw of a 2-3 Amps but this fluctuates too. After the control panel and other bits of general drain, that’s very little, possibly no, current being pulled through.

I think an inverter is a pretty simple device so thought a cheap one would be fine. Is it worth spending a bit more to see if that makes a difference - or is it likely to be some other problem?

Thanks
Chris

1, a 500w sinewave inverter at £15 doesnt exist. You may think its a 500w sinewave inverter but it isnt.
2, A sinewave inverter is a complicated piece of equipment.
3, The voltages you are seeing proves no 1
4, At £15 it wont be made to any safe or approved standars
5, Bin it before you cause damage to your laptop or have a fire or electrocute yourself
6, Go buy something that will work, last, not kill you. Like http://rover.ebay.com/rover/1/710-5...0001&campid=5338547443&icep_item=222681572461

 

[peterc10]

Hi All,

I have a cheap 500w/1000w pure sine wave inverter (about £15 from Malaysia on eBay) and just tested it on my wife’s, very powerful laptop. The power block says it’ll accept anything from 100-240v, with a maximum draw of 10.4A.

Are you sure of those figures. 10.4A at 240v equates to 2500W. If that is the correct figure you should be able to heat your motorhome with the laptop, because it is the equivalent of a 2 bar electric fire (in old fashioned terms).

 

[funflair]

Are you sure of those figures. 10.4A at 240v equates to 2500W. If that is the correct figure you should be able to heat your motorhome with the laptop, because it is the equivalent of a 2 bar electric fire (in old fashioned terms).

My Guess would be the 10.4 amps is into the computer but we don't know the volts, this is why sticking with Watts is less confusing.

Martin

 

[chenderson1965]

Are you sure of those figures. 10.4A at 240v equates to 2500W. If that is the correct figure you should be able to heat your motorhome with the laptop, because it is the equivalent of a 2 bar electric fire (in old fashioned terms).

Yep. suspect it's a peak draw number.

 

[chenderson1965]

You don't need an inverter. The laptop uses low voltage DC, so it's daft and wasteful to invert up and then transform back down. Buy a 12v adaptor for it. Just search Amazon with the name and model number of your laptop.

Thought of that. Unfortunately, the output is 19.5v and I can't find one that will do the right current and voltage output.

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[peterc10]

Thought of that. Unfortunately, the output is 19.5v and I can't find one that will do the right current and voltage output.

As I say the easiest thing to do is search using the name and model of the laptop and "car adaptor" or "12v". My previous HP laptop was about 21v from memory and I found an adaptor for it easily. As Martin says, check the wattage not the amps, to be sure.

 

[chenderson1965]

As I say the easiest thing to do is search using the name and model of the laptop and "car adaptor" or "12v". My previous HP laptop was about 21v from memory and I found an adaptor for it easily. As Martin says, check the wattage not the amps, to be sure.

Done that. Can’t find one with more than 135w and the laptop needs 200w.

 

[Gromett]

At £15 it is most certainly not a pure sine wave inverter. It is likely a modified sine wave or quasi sine wave at best.

That said, judging by your battery voltages, it is simply trying to pull too much power from the battery. A 200Watt laptop charger seems excessive to me, but 200 watts at 12v nominal is 16 amps which doesn't sound beyond the capabilities of even a small lead acid battery in good condition.
Suggests to me either your inverter is faulty, your charger doesn't like modified sine wave or the spec is wrong on the inverter and it just isn't capable of that sort of juice.

I have just put a 300 watt pure sine wave inverter on the classifieds at £60 second hand. That is about right for a pure sine wave inverter in my view.

 

[peterc10]

Done that. Can’t find one with more than 135w and the laptop needs 200w.

What is the name of this computer and where did the 200W come from?

 

[Otter Spotter]

Hi All,

I have a cheap 500w/1000w pure sine wave inverter (about £15 from Malaysia on eBay) and just tested it on my wife’s, very powerful laptop. The power block says it’ll accept anything from 100-240v, with a maximum draw of 10.4A.

The lights on the inverter illuminate, so there’s definitely power but the indicator on the laptop doesn’t indicate that the battery is charging. The inverter fan pulses in and off and the voltages indicated on the inverter fluctuate. On the dc side from 12.8v down to 9v (the battery is full) and on the AC side from 240 to 110v (and I think I even saw 24v at one point)

I checked that the output socket was live with a different plug and it is.

Connecting and disconnecting whilst watching the current indicator on the control panel suggests a draw of a 2-3 Amps but this fluctuates too. After the control panel and other bits of general drain, that’s very little, possibly no, current being pulled through.

I think an inverter is a pretty simple device so thought a cheap one would be fine. Is it worth spending a bit more to see if that makes a difference - or is it likely to be some other problem?

Thanks
Chris

Are you really sure it’s a pure sine wave invertor? For £15 when they are normally £200 +for a very low wattage one . To charge a laptop you really should be using a pure sine wave one.

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