Laptop using an inverter

[stuart23]

On my boat I have a small inverter I got a few years ago which I use to charge my phone...The inverter has on it

NIKKAI 150W DC-AC POWER INVERTER AC OUTLET 230V / 50 HZ

So today I took my laptop with me to see if I could use it on the boat.

The battery on the laptop is dead.

When I connected it to the inverter and switched the laptop on, the light on the laptop came on briefly, then it and the light on the inverter went out.

I tried it a couple if times.

Can anyone explain this?...Is it that the 150W inverter is not powerful enough to run a laptop?...and do you think if I got a new battery for the laptop. I would be able to charge it up using the inverter? (at the time the engine was running...so can I presume there was enough electricity available?)

Edited October 4, 2008 by stuart23

[twocvbloke]

I'd say the laptop is not the problem, unless it's some high-end gaming laptop, they shouldn't draw more than 150w just to charge or power up, so it could be the inverter or an incompatibility between the laptop's charger and the inverter. Try running a 60w bulb off the inverter to see what it does, it may have a fault which never showed up when you used your phone charger, and if possible try another inverter...

 

I have a 100w inverter which powers my Toshiba Satellite A50 fine, although I haven't used it much...

 

Also, try taking out the battery from the laptop if it is "dead" dead, it could be causing problems of it's own...

Edited October 4, 2008 by twocvbloke

[Keeping Up]

Almost certainly this indicates that the inverter is not powerful enough to run your laptop.

 

It may just be possible that it was also trying to charge the (dead) battery at the same time, in which case you MIGHT be lucky enough to be able to run the laptop if you start with a fully charged new battery - but probably not.

 

What you might be able to do is to run the laptop from a battery, if you buy a new one, and then recharge the battery after switching the laptop off again. But again, you may not.

 

A bigger inverter is probably your best solution - and a new battery for that time when you were just about to save all your work when the battery glitches and the inverter drops out!

[bottle]

I think you will find that your inverter is not large enough.

 

My laptop requires (via its blackbox) 240v and 1.5 amps.

 

This equates to 360VA,

 

I run mine on a 300watt inverter.

[twocvbloke]

I think you will find that your inverter is not large enough.

 

My laptop requires (via its blackbox) 240v and 1.5 amps.

 

This equates to 360VA,

 

I run mine on a 300watt inverter.

 

That's the mains side you're measuring, what about the DC side? My laptop's PSU only equates to about 60w on the DC side (15v 4A), and the PSU shouldn't need to take up to 300w for a laptop, unless you have a high-end gaming laptop...

[bottle]

It requires 90 watts (4.74 amps) at 19v DC,

 

It is not a games machine, do not play any.

[magnetman]

if you turn the inverter on with the laptop not connected, wait for the laptop power supply transformer to stop ticking (listen to it) then when its buzzing quietly insert the plug into the back of the laptop. that might work. mine sometimes spits the dummy if its plugged in before the inverter is switched on. i'm using a nikkai 150w inverter.

[DHutch]

My laptop charge is 70w. However its obvously not a purely resitive load, and i bealve switched mode power supplys (SMPSU) arnt a fan of running on a modified sinewave. Possably visa versa. So it might be closer than you might think.

 

Who knows. Gibbo?

- Mine will run fine of my 300va maplins/acdc MSW inverter. Although when the batterys charging while the laptops also on it does growl plenty.

- Also if i used the charger on its 12v input off a lighter socket (iJuice charger, used for runing laptop in car) it trips the 24->12v box (24v boat) t knocks it out even tho it should be with spec (states i requres an 8amp feed, box is rated at 10a continuse)

 

 

Daniel

[sueb]

I use 12v for phone charging and my laptop. The laptop uses a Maplins thingy that has been mentioned before on this forum. It is adjustable for various volts. Why use 240v?

Sue

[Peter R]

On my boat I have a small inverter I got a few years ago which I use to charge my phone...The inverter has on it

NIKKAI 150W DC-AC POWER INVERTER AC OUTLET 230V / 50 HZ

So today I took my laptop with me to see if I could use it on the boat.

The battery on the laptop is dead.

When I connected it to the inverter and switched the laptop on, the light on the laptop came on briefly, then it and the light on the inverter went out.

I tried it a couple if times.

Can anyone explain this?...Is it that the 150W inverter is not powerful enough to run a laptop?...and do you think if I got a new battery for the laptop. I would be able to charge it up using the inverter? (at the time the engine was running...so can I presume there was enough electricity available?)

 

If the inverter stayed on but the laptop didn't charge, then I think that would suggest that the charger doesn't like the inverter output. However, since the inverter drops out it does suggest to me that the inverter can't supply enough power. Laptops power requirements vary a lot, the power pack for my current one says 65W, it's predecessor was 135W.

 

Therefore, the first check is what is the rated power of the laptop power supply (should be on the label somewhere!)

 

However, another thought also occurs - how is the inverter connected to the 12V supply? 150W at 12V equates to 12.5Amps, if the 12V wiring isn't up to carrying this power it could be that the load of the laptop is creating sufficient voltage drop on the 12V wiring for the inverter to give up on 'under-voltage' even though the load may be within it's rating. If it is hard-wired I would hope the wiring was adequate, but if the inverter is of the type that plugs into a 'cigarette lighter' type socket (which it could be at 150W), the wiring to the socket might not be up to the job.

 

Peter

[smileypete]

On my boat I have a small inverter I got a few years ago which I use to charge my phone...The inverter has on it

NIKKAI 150W DC-AC POWER INVERTER AC OUTLET 230V / 50 HZ

So today I took my laptop with me to see if I could use it on the boat.

The battery on the laptop is dead.

When I connected it to the inverter and switched the laptop on, the light on the laptop came on briefly, then it and the light on the inverter went out.

I tried it a couple if times.

Can anyone explain this?...Is it that the 150W inverter is not powerful enough to run a laptop?...and do you think if I got a new battery for the laptop. I would be able to charge it up using the inverter? (at the time the engine was running...so can I presume there was enough electricity available?)

 

Hi,

 

As I mentioned on another thread, these sort of power supplies take current in short bursts that are more likely to overload an inverter.

 

To get a guaranteed result work out the input 'VA' of the power supply from its label. If the label says 'Input: 240V, 1.5A' then a 360W or higher inverter is needed.

 

Though you may find you can run it on an inverter with a little less power, as bottle has done.

 

 

In the meantime you could try charging the laptop battery without turning the laptop on, or take the battery out if you need to use the laptop before it's charged.

 

cheers,

Pete.

[stuart23]

Thanks for all the replies.

The laptop is a Toshiba Satellite Pro L20,

on the underneath of the laptop is a label saying:

3.42A DC19V

Can't see any other reference to electrical power

[magnetman]

if you turn the inverter on with the laptop not connected, wait for the laptop power supply transformer to stop ticking (listen to it) then when its buzzing quietly insert the plug into the back of the laptop. that might work. mine sometimes spits the dummy if its plugged in before the inverter is switched on. i'm using a nikkai 150w inverter.

 

 

have you tried this? I had to do it this morning on my laptop/nikkai 150w inverter as i had switched the inverter off with the laptop plugged in and it wouldn't work this morning when i switched the inverter on. took the plug out of the back of the computer and the laptop's power supply went from ticking to buzzing then plugged the laptop back in and it worked. I have found this happens on several different laptops including one which was rated at 20v 3.25A.

 

 

The other thing I've had before is bad connection in inverter-to-battery cable which caused voltage drop as mentioned earlier by someone.

[smileypete]

Thanks for all the replies.

The laptop is a Toshiba Satellite Pro L20,

on the underneath of the laptop is a label saying:

3.42A DC19V

Can't see any other reference to electrical power

 

Have a look on the power adapter.

 

It should say something like 'Input 100-240V 1.5A' or something like that.

 

cheers,

Pete.

[magnetman]

Have a look on the power adapter.

 

It should say something like 'Input 100-240V 1.5A' or something like that.

 

cheers,

Pete.

This is an interesting point. one of my laptops power supplies says 100-240v 1.7A. I thought that 1.7A@240v would be 1.7x240 which is 408 watts . way over the inverter's output but it does work on that inverter (double checked and it is a 150w Nikkai). the inverter does say 450w surge and 'soft start' I think the 'soft start' bit might be why it is necessary to unplug the computer and plug it back in again.

 

its a bit odd maybe the 1.7A refers to 100V and not 240v?

[smileypete]

This is an interesting point. one of my laptops power supplies says 100-240v 1.7A. I thought that 1.7A@240v would be 1.7x240 which is 408 watts

 

It's not the average input current, it's the peak input current, and occurs over a small percentage of time.

 

A smaller inverter may work, but there's no guarantee it will, hence this thread.

 

 

BUT thinking about it, it should be OK to divide the inverter power requirement by 1.414.

 

So the minimum size inverter that should work would be (240*1.7)/1.414 = 288W

 

 

The reason why? Say a 240V inverter is running a 240W heater.

 

Although the input current to the heater is nominally 1 amp, this actually varies between 0A and 1.414A as it's a constantly varying alternating current (AC) and not a steady current (DC).

 

So an inverter that can supply 240W should be OK supplying 1.414A peak input current to a laptop power supply.

 

 

So summing up:

 

Inverter output voltage * power supply input current = size of inverter that's guaranteed to work.

 

Divide the above by 1.414 = inverter size that should work.

 

Using a smaller inverter still may or may not work.

 

cheers,

Pete.

Edited October 5, 2008 by smileypete

[chris w]

If the inverter is not a pure sinewave type then (assuming it's an approximate squarewave type instead) peak current is not 1.414 x RMS current. In the case of a squarewave, peak current = RMS current.

 

Chris

[smileypete]

If the inverter is not a pure sinewave type then (assuming it's an approximate squarewave type instead) peak current is not 1.414 x RMS current. In the case of a squarewave, peak current = RMS current.

 

Good point, so for MSW inverters it's back to:

 

Inverter output voltage * power supply input current = size of inverter that's guaranteed to work.

 

Using a smaller inverter may or may not work.

 

cheers,

Pete.

Edited October 6, 2008 by smileypete

[Hawksey]

I had the same problem. Try it with the engine running ~ it maybe your boat batteries are a bit too flat to get the inverter started and working

[alan_fincher]

You can avoid an inverter altogether by using something like this....

 

http://www.maplin.co.uk/Module.aspx?ModuleNo=44736

 

or this

 

http://www.maplin.co.uk/Module.aspx?ModuleNo=223723

 

depending on power requirements of the laptop.

 

Sadly the higher power one was until recently at £20 rather than £40, but that offer seems to have ended.

 

You may find cheaper alternatives elsewhere.

 

Alan

[johnandcharlie]

Thanks for all the replies.

The laptop is a Toshiba Satellite Pro L20,

on the underneath of the laptop is a label saying:

3.42A DC19V

Can't see any other reference to electrical power

I've got a Satellite Pro with the same rating. I use a Maplins 120w Laptop Power Adaptor (http://www.maplin.co.uk/Module.aspx?ModuleNo=44736 as mentioned in another post). As I almost always use it in my van, I run it with the battery removed, in Long Life power mode it draws around 1.9 amps, and I can run it comfortably for several hours a day in summer from my solar panel. When charging the battery it draws around 5 amps.

 

I don't know if you have similar wiring to my van, but the built in 12 volt socket has a maximum load of 4 amps, and I couldn't run my laptop with battery installed off my 150 watt inverter through it. I've installed extra sockets connected to my solar charge controller, so have 10 amps available on them.

[dr pepper]

your laptop power supply will be a switch mode type, these have large capacitors which take an inrush when you first apply power, some inverters can withstand being overated for a short period, my 300w one will supply 2000 w for a short time, yurs may not have this extra capacity.

you can get special laptop supplies, cpc do them, it looks just like your original mains powered adapter but has a fag lighter on the end instead of a 3 pin mains plug, they convert 12volt to 19 volt used by lapy's this will obviate the need for your inverter and would be a better idea, i think they ar around 15 quid, and they come with a selection of connectors. for diffrerent lappy's.