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12v - 230v power inverters
blakep82 - 29/5/10 at 10:26 PM

any experience of them? going down to south england this weekend, and i'll want to use my laptop in the car on the way down. thought about getting one of those inverters. what sort of power do i look at for a laptop?
how do i work out the power consuption of the PSU? thought it would say how many watts it takes on the lable, but it doesn't.

what do i need to look for? where's good to get one? i'll need it here by weds if i get one. looked in halfords today, they look more expensive than i remember


RazMan - 29/5/10 at 10:34 PM

I think it might be better to get a DC/DC convertor as they will be more efficient. Your lappy probably runs on 15V dc so why convert 12Vdc to 240Vac and then back to 15Vdc - those invertors are not very efficient and a lot of the power gets converted into heat.
I've got a cheap Chinese ciggy lighter 15V 65W power supply which works really well.

[Edited on 29-5-10 by RazMan]


blakep82 - 29/5/10 at 10:40 PM

ah yeah, hadn't thought about that. laptop runs at 20v anyway i think. also its got a weird plug on it, so not an easy job plugging it right into the lighter. going to look at the misco site to see if they have anything specifically for the job


wilkingj - 29/5/10 at 10:44 PM

If you keep the engine running its not a problem at all.

Remember that the max power drawn will depend on the load.
A 500W inverter does not draw 500 watts if you stick a 100w Load on it. It will only draw what ever the load put on it is.

Bear in mind that if your lappy draws 100w, then a 150watt inverter will run a bit on the warmside, and a 500w one will take it all without blinking. Same as getting 200BHP from a 1 litre engine, or from a V8

SO.... look at the power rating on the Lappy power supply. Thats the MAX it will draw, and probably be a bit less.

Now, (and to keep the maths easy as its late!)

A 240watt load, draws 1 Amp at 240 Volts.
However if drawn through an inverter beng fed from 12 Volts., the Drain on the 12V battery is at least 20 amps

P=IxV ie 240w = 1 amp x 240V

BUT when supplied by a 12V battery
240w = 20Amps x 12V
So you can see the drain on a 12V battery is SIGNIFICANT at 20 amps in this example.

If you are running your lappy whilst the the vehicle is on the move, it should not be a problem, as the Car alternator can deliver 20 amps easily (and more for most newer cars).

Also keep the inverter in an open space where it can have some air around it, they usually generate a little bit of heat!
ie dont stick it under a blanket or your coat!

If you are stationary, then be aware you could drain the car battery to a point you cant start the engine!

Just be aware of this limitation.
Oh and pack a set of Jump leads as a precaution. Its easy to get a jump start from ANY car. However without a set of jump leads is a bit more difficult.
Have fun.


T Rex - 29/5/10 at 11:48 PM

Aldi had some for 14.99 that will just power a laptop i bought one for work as i am oftern on site ant the charge in the battery is not enough.


blakep82 - 29/5/10 at 11:49 PM

^ ooh, will have a look. if i have an aldi near here. don't think i do actually. got a lidl. might be an aldi in port glasgow perhaps... that would do me you see,


MikeRJ - 30/5/10 at 01:23 AM

quote:
Originally posted by wilkingj
If you keep the engine running its not a problem at all.

Remember that the max power drawn will depend on the load.
A 500W inverter does not draw 500 watts if you stick a 100w Load on it. It will only draw what ever the load put on it is.


Plus some extra as they aren't anywhere close to 100% efficient!


rusty nuts - 30/5/10 at 06:57 AM

I used a Clarke inverter when I was setting my ECU because the battery in my laptop doesn't seem to last very long . Worked for me but it may be better to get the correct item if possible?


thunderace - 30/5/10 at 08:57 AM

i got a great one from argos £13.99 Black and Decker 400w Power Inverter.

http://www.argos.co.uk/static/Product/partNumber/3402124/Trail/searchtext%3EINVERTOR.htm

SRY JUST LOOKED THERE OUT OF STOCK.

[Edited on 30/5/10 by thunderace]


jossey - 30/5/10 at 10:59 AM

i have a spare one its 150watt you can have it for £10 delivered.

it works on my laptop but i dont need it now i got a cig lighter one for my lappy.

cheers


tegwin - 30/5/10 at 11:06 AM

Maplins sell laptop power supplies...

I assume if yours has a weird plug its a Dell?

If so, Dell supply specific car power supplies


carlknight1982 - 30/5/10 at 01:55 PM

150W is more than adequet for a lappy, i have a 3000W one in my van and a duel charging circuit running off 2 truck batteries and i can use it to run a microwave and a small kettle, great things


blakep82 - 31/5/10 at 09:00 PM

quote:
Originally posted by jossey
i have a spare one its 150watt you can have it for £10 delivered.

it works on my laptop but i dont need it now i got a cig lighter one for my lappy.

cheers


cheers everyone, and Jossey (i'd have had that, but i can't find the dongle thing i need for the computer to run the software i wanted now so i won't bother with it)

not a dell, its a lenovo one. ah well, it was a fun idea, but looks like i'll be doing most of the driving anyway. fine by me, makes sure i get the most space