How much battery dd your lappy have before you pluged it in■■? some wont have enough power to run if flat even off the inverter.
Try having a full battry on the lappy and then using the inverter as its just pulling enough power to trickel feed.
Try chargig the battery with the lappy off and then use it with the inverter… If you get my meaning 
your laptop needs a constant supply to charge properly those standard invertors do not do this,the charge they produce is a pulse, therefore it won’t charge properly and could even damage your lappy
you need to get one from pc world which costs around £24(if i can find the link will put it up for ya)
i have one and it works a treat 
better still if you can get power to lappy take the battery out
result less strain on inverter and lappy still works
If you have plugged it into the 24v socket then you may well have toasted it. Try it in your car. If it doesn’t work then you have trashed it. Some dishonest people might return it to the retailer for exchange, omitting to mention the confusion about voltages but I couldn’t possibly condone that.
I also think a 140w inverter is pushing it a bit for a lappy, 300w is probably a better spec.
Harry Monk:
I also think a 140w inverter is pushing it a bit for a lappy, 300w is probably a better spec.
I ran mine for about 2 years H, never unplugged it or turned it off on the Belkin power unit.
Simple answer to your question is. 24v will damage your 12v items beyond repair (I blew up my tomtom, as i plugged it into 24v socket using a 12v charger). You can buy 24v inverters, Whatever you do, do not upgrade your fuse for the 12v socket. The fuse is there for a reason, there is also a reason for it being the rating it is. Fitting a higher rated fuse could cause your wiring to catch fire if you draw more power than the cable can carry.
If you can, speak to your fitter, and get them to uprate your wiring & fuse to your 12v socket, or get them to install a 3 pin plug outlet wired up to the battery, as this will allow you to use items that draw a lot more power than the 12v socket
Have a read of this thread. Lee G had a similar problem but he swapped his coolbox, dont think Ebay will do that.
ive got one of these & it charges my 15" laptop with no problems, 19.99 from maplins.
Thetaff:
your laptop needs a constant supply to charge properly those standard invertors do not do this,the charge they produce is a pulse, therefore it won’t charge properly and could even damage your lappy
What is AC? Oh, that’s right, it’s a sinewave which is a pulse.
i blew mine up in dublin not to long ago… Not fun i tell you sparks and smoke everywhere with laptop still plugged in… thought the lot was going to go on fire… made great fireworks though…