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[doz]

If I wanted to run a laptop which is rated at 1.7 amps. What rating would I need on the power inverter?

[tidla]

W
IxV

?
1.7x12

21w

200w should be plenty

[TheBoy]

If I wanted to run a laptop which is rated at 1.7 amps. What rating would I need on the power inverter?

I assume thats at 18-20v?  On the face of it, 100W should be enough, but inrush currents on SMPS may be too much.

Inverters aren't particularly efficient, and will soon kill a car battery if the car isn't running.


Most laptops should last 4-5hrs with ease. Would a 2nd battery, or a high capacity battery, be a better option?

[doz]

It's for the camper. Has a split charge and twin batteries.

[Abiton]

I used a 300W to run a laptop last time I went camping , with no problems.  It has an inbuilt 'you've taken the piss' low-battery-voltage audible warning so I didn't have to be anxious about the car starting.  Said alarm never went off though.

[05omegav6]

Had a 2kw one on the boat, powered by two leisure batteries. Would power an A rated Bosch fridge for three days on its own, but put the telly on with the heating and four hours was its limit

Wasn't such a big deal though, as the engine doubled up as the boiler for the hot water, so was run for 2-3 hours a day

[Andy H]

W
IxV

?
1.7x12

21w

200w should be plenty

Where did you get 12 Volts

Got two laptops in front of me & one requires 15V the other 19V.

The most efficient way would be to get hold of a switch mode "step-up" regulator to take anything from 11V-14.5V and output whatever the laptop requires.

[ZacVegas]

I run my laptop from a 90watt inverter I got from towsure for 17quid 

[doz]

Laptop is rated at 110-240 1.7 amp. Output is 18 volts

[TheBoy]

Laptop is rated at 110-240 1.7 amp. Output is 18 volts

Jeez

How old is it?

1.7A at 110v puts it just shy of 200W

Sure you've read it right?

[doz]

Yep. It's fairly old. Running XP. It's an old one I use in the garage and not to bothered about it

[ozzycat]

i run a 300w invertor this enough to run the battery charger on my scooter when its in the car

[tidla]

the volts pushing the 1.7 A is 18v.

1.7x18=30w

[dbdb]

the volts pushing the 1.7 A is 18v.

1.7x18=30w

Spot on. So that's approx 30W at 230V too.

Generally you need at least double the wattage of inverter (because inverter manufacturers lie, basically) so a 100W inverter would be fine, putting out over 30W at 230V into your charger which then wastes a bit and puts out 30W at 18V to your laptop. Alternatively you could get a 12V to 18V inverter and bypass your charger, I know these are available for small loads. Frankly though for a laptop it is probably not worth risking the voltage being out, not to mention wrong polarity and ac/dc issues. In fact if you get an inverter best to get a pure sine wave one. Twice the price but a modified sine wave one often blows chargers.  Lots of reasonable and cheap inverters available from China on ebay.

[doz]

Something like this should do the job then?

http://www.ebay.co.uk/itm/500W-Power-Inverter-convert-12v-DC-to-230v-AC-/400234658288?pt=UK_Campervan_Caravan_Accessories&hash=item5d2fd839f0