Inverter question (1 Viewer)

[lostinfrance]

New to motorhoming.... I'd like to use my laptop in motorhome. If I buy an inverter, where does it plug in? Do I plug it into the cigarette lighter? Would that be running off the engine battery?

Can it be run off the leisure battery? How would you connect it to leisure battery?

I'd appreciate any advice, thanks.

Cheers

Louise and Roy

 

[Douglas]

Basically it depends on the size of the inverter, the small ones do come with the cigar type plugs fitted and that will be fine but the big ones, 1 or 2Kw need to be connected as close to the battery as possible.

Unlike AC voltage DC looses voltage very quickly as it travels down the cable so the closer to the battery the better also the size of the power cables has a similar effect so the bigger the cable the better.

And yes the cigar type plug is normaly run from the engine battery.
Doug...

 

[sinbad1]

New to motorhoming.... I'd like to use my laptop in motorhome. If I buy an inverter, where does it plug in? Do I plug it into the cigarette lighter? Would that be running off the engine battery?

Can it be run off the leisure battery? How would you connect it to leisure battery?

I'd appreciate any advice, thanks.

Cheers

Louise and Roy

My advice would be to get a 12v to ...19v converter from maplins why get an inverter 12v to 240v only then to be transformed back to 19v click here

regards

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[Snowbird]

Hi,some laptops wont work from an inverter,My HP wont.If you just nead to charge your laptop it makes more sense to get a dedicated 12volt charger to plug into your cig, socket.Regards,Dave.

 

[lostinfrance]

Does that stay plugged in while you are driving, so it charges from the vehicle battery?

 

[pappajohn]

i have a 600w inverter connected to the leisure batteries.
the cable length is around 400mm and the size is the same as the engine starter motor wires....cross section of around 25mmsq.

my lappy transformer has a power consumption of 1.5amps @230v
but through the inverter it will be drawing 30amps+ @ 12v from the batteries and will soon drain a leisure battery.

unless you have a very big battery bank (i have 3 batteries giving a total of 330ah)and solar panels, inverters should only be used sparingly.

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[Snowbird]

Does that stay plugged in while you are driving, so it charges from the vehicle battery?

When you are driving or stationary,dont think it matters much.We use ours in car as well as RV.

 

[lostinfrance]

Thanks for all your replies. Very helpful.

Appreciated

Louise and Roy

 

[sinbad1]

i have a 600w inverter connected to the leisure batteries.
the cable length is around 400mm and the size is the same as the engine starter motor wires....cross section of around 25mmsq.

my lappy transformer has a power consumption of 1.5amps @230v
but through the inverter it will be drawing 30amps+ @ 12v from the batteries and will soon drain a leisure battery.

unless you have a very big battery bank (i have 3 batteries giving a total of 330ah)and solar panels, inverters should only be used sparingly.

30Amps

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[JeanLuc]

If you go to the downloads section (link on left hand side of the home page) there is a file I put there called "Install a small Inverter.pdf". It is in the Misc. section (also featured in the latest downloads list at present). That document discusses why I installed an inverter mainly for the purposes of running a laptop, and explains why I moved away from a simple cigar-lighter connection for the inverter, having suffered problems with voltage drop (in a Hymer). I can run the laptop (85W Apple power adapter) and run a set of powered speakers at the same time with very little current draw off the leisure batteries. Have a look.


Philip

 

[pappajohn]

30Amps

yep!!!

volts multiplied by amps = watts

230v X 1.5amp = 345w

therefore,

watts divided by volts = amps

345w / 12v = 28.75amps plus losses in the inverter.:thumb:

unless i got it wrongoh:

 

[sinbad1]

yep!!!

volts multiplied by amps = watts

230v X 1.5amp = 345w

therefore,

watts divided by volts = amps

345w / 12v = 28.75amps plus losses in the inverter.:thumb:

unless i got it wrongoh:

Hey you must have a big laptop to power mine it only requires 90w @ 18.5v you need a smaller lappy John

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[Tony Lee]

Pappajohn, you may be using the maximum rated power of the laptop power supply as the actual power. Normally laptops take less than 100Watts.

This is still 7 to 10 amps out of the battery and must be monitored if you need to use the computer for long periods - otherwise it will run the battery flat.

Makes sense to have it on charge while you are driving and run it off its own batteries when stationary

 

[pappajohn]

Hey you must have a big laptop to power mine it only requires 90w @ 18.5v you need a smaller lappy John

agreed.....the output side of my lappy transformer is 5amps @ 15v which is only 75watts

but the inverter will still draw 28.75amp (345w) @ 12v from the battery to give an input of 1.5a @ 230v to the transformer.

it aint what power the lappy needs but what the transformer needs.

 

[pappajohn]

Pappajohn, you may be using the maximum rated power of the laptop power supply as the actual power. Normally laptops take less than 100Watts.

This is still 7 to 10 amps out of the battery and must be monitored if you need to use the computer for long periods - otherwise it will run the battery flat.

Makes sense to have it on charge while you are driving and run it off its own batteries when stationary

very true Tony....but as its the only reference point we have (without metering equipment) i think that has to be the benchmark.........:thumb:

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[sinbad1]

agreed.....the output side of my lappy transformer is 5amps @ 15v which is only 75watts

but the inverter will still draw 28.75amp (345w) @ 12v from the battery to give an input of 1.5a @ 230v to the transformer.

it aint what power the lappy needs but what the transformer needs.

Come on John that don't make any sense, any item that consumes energy is rated in watts and as you say divided by the voltage gives the current , admittedly there is some loss of energy transforming from 12 to 240v ;but its only providing the current to run the lappy which i guess is no more than 10A

Where does the other 20A go then John?

 

[Douglas]

30Amps

He often gets it wrong. don't worry about it. Its all flash and no substance.

Doug...

 

[lostinfrance]

Thanks. I'll go and find the .pdf and have a read.

So much to learn when you are new to motorhoming!

Cheers, Louise and Roy

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[barbt]

We bought our inverter from NETPC for about £20 and plug it into the cigarette lighter, it runs the laptop perfectly and also of course is good to charge the phones and camcorder.

 

[GOREFISH64]

HOW TO REGISTER A VEHICLE IN FRANCE
:thumb:

 

[Wildman]

HOW TO REGISTER A VEHICLE IN FRANCE
:thumb:

Hi is this a statement or a question and either way what is the relevance to this thread.
maybe you need to start a new thread and be a bit more specific about what you actually want.

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[sinbad1]

Thanks. I'll go and find the .pdf and have a read.

So much to learn when you are new to motorhoming!

Cheers, Louise and Roy

apologies if this thread has go somewhat technical and probably over your head

The answer to most of your questions are explained CLICK HERE

question 5 regarding inverter types should be noted if that's the way you want to power your lappy, personally i wouldn't run sensitive things like laptops on a modified sine wave, some do may get away with it ;but there is a risk.

you don't get these problems with 12DC to 19vDC converters


Regards

 

[DESCO]

posted in error senior moment sorry

 

[hilldweller]

you don't get these problems with 12DC to 19vDC converters
Regards

Ah, but you can !

I had a big 17" laptop with 64 bit processor. Ran off a Trust 120W PSU a treat.

MOBO died.

Replace with 15" dual core Gateway 19V 3.42A. This totally freaks out the Trust. The charge LED on the laptop keeps cycling on/off. Must be some horrible surge during charging.

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[sinbad1]

Ah, but you can !

I had a big 17" laptop with 64 bit processor. Ran off a Trust 120W PSU a treat.

MOBO died.

Replace with 15" dual core Gateway 19V 3.42A. This totally freaks out the Trust. The charge LED on the laptop keeps cycling on/off. Must be some horrible surge during charging.

Never had any problems with mine ;but it is a good quality one with adjustable voltage and stabiliser, seems logical to me to use a DC to DC, rather than DC to AC to DC and introduce problems associated with modified sine waves.

Don't get me wrong these inverters are great for most things, and if you can afford a pure sine wave even better. Being a tight git, i could only afford a cheap B&D 400w inverter, setup is simular to that which jeanLuc has done;but wouldn't use it for lappy cant afford to pod out £500

regards

 

[cater_racer]

I think DC to DC converters are worse! If they take 12v DC and give out 19V DC they must go via a AC phase. You just can't get more voltage out of a source without it.

So most DC to Dc converters have a square wave switching oscillator and a small transformer, usually a torroid or similar. This is driven by the square wave switch, which has nasty high frequency harmonics which are partially removed via smoothing chokes and/or capacitance.

A 12v dc modified sinewave 50Hz inverter producing 230v ac also switches via square wave, and uses a "leaky" CVT type transformer to create the output, the slight advantage in this for your laptop is; the switch rate is lower (50Hz) and does not have quite so many nasty HF harmonics, and the spikes to voltage ratio is lower due to the fact the 230V output.

This is then usually fed into your laptop via it's standard (inverter based) power supply, which in turn has spike and harmonic suppression which the laptop maker designed to provide a clean output their laptop can use.

So all in all, I would suggest the modified sinewave unit would be better for sensitive devices.

Just keep the inverter physically away from the laptop, and the laptop PSU. Don't cramp them up close together as electro magnetic radiation can carry across devices, a metre apart would be more than adequate.


Cater_Racer (retired electronic inverter design engineer)

 

[Jackomet]

Inverter

Going from 12v direct to 19v or what ever the laptop requires is logically the way to go, unfortunately most of the latest and popular laptops Dell et al have logic built into "their" power supplies that prevents using any other supply. I tried this already, anyone want a 12v to 19v Maplin converter?
JK

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[pappajohn]

Come on John that don't make any sense, any item that consumes energy is rated in watts and as you say divided by the voltage gives the current , admittedly there is some loss of energy transforming from 12 to 240v ;but its only providing the current to run the lappy which i guess is no more than 10A

Where does the other 20A go then John?

my most sincere apologies to anyone having sleepless nights/cold sweats/ palpitations/ raised blood pressure due to my posts.......

Oh bugger it!!!!! i was wrong.:Blush: Ok!!!!

to prove a point i just took my lappy out to the van and connected it to the invertor hoping to see 30amps.

lappy doing zilch but displaying web page......7.7amps from battery at the inverter input lead.

anyone wanting to start a new thread named......."ignore this idiot at all cost" then please go aheadoh:

going to bury me 'ead in the garden now:Sad:

 

[Douglas]

I think DC to DC converters are worse! If they take 12v DC and give out 19V DC they must go via a AC phase. You just can't get more voltage out of a source without it.

WRONG WRONG WRONG

Check this. Not a sign of AC anywhere.

MAX1674 or MAX7176. This is step-up DC-DC converter that can convert voltages from 0.7V to any in range from 2V to 5.5V. MAX1676 have already preset pins for 3.3V and 5V, that makes easer integration in 3.3 and 5V circuits. IC can dissipate up to 444mW.

Doug...

 

[sinbad1]

my most sincere apologies to anyone having sleepless nights/cold sweats/ palpitations/ raised blood pressure due to my posts.......

Oh bugger it!!!!! i was wrong.:Blush: Ok!!!!

to prove a point i just took my lappy out to the van and connected it to the invertor hoping to see 30amps.

lappy doing zilch but displaying web page......7.7amps from battery at the inverter input lead.

anyone wanting to start a new thread named......."ignore this idiot at all cost" then please go aheadoh:

going to bury me 'ead in the garden now:Sad:

Hey come on John We all get our undies wrapped over from time to time
Most of your advice is spot on mate so keep taking the tablets I do


Regards