# Inverter choice. How many watts? Which inverter



## Pudsey_Bear (Sep 25, 2008)

Because I've had a load of help from this site, I've had a go at putting something back in, to hopefully help others.

Below is a guide to what size inverter you would need to power various appliances, I have obviously not done the calculations myself, as I am not qualified to do so, but have gathered the information from various web sites, I think it is as correct as possible, but many appliance manufacturers will have different input wattages, and this is intended as a guide only.

It is very simple to understand; find your appliance, go along the line until you find a green smiley face, and an inverter of that wattage should be up to the job, but remember some inverters are not as described and have losses while in use, so you may need the next one up, some inverters also have a surge, this is what it says, a surge of current usually double that of the stated power output of the inverter, but lasts less then 0.5 of a second.

Also note that the bigger the inverter the bigger the cables, fuses, and battery power need to be, for most purposes a small 300 watt cigarette lighter socket inverter is all most people will ever need, unless you need to run larger electrical appliances away from electric hook up.

If you find any errors, please let me know, but remember it is a guide only.

It is a little on the small side to read, but clicking it does help a little, constraints of the site I'm afraid, 100kb is not a lot.

Kev.


----------



## Pudsey_Bear (Sep 25, 2008)

I was wondering if anyone had found this inverter guide of any use.

Kev.


----------



## sallytrafic (Jan 17, 2006)

I think you should have a new category of smiley face as well. Using a 3000W inverter to charge a 5 to 10W mobile phone charger (mines only 3W) will work but consume an awful lot of extra power so the faces could be orange after the 150W charger meaning it will do it but hey you will be wasting energy.


----------



## Pudsey_Bear (Sep 25, 2008)

Nice one Frank,

Mistakenly perhaps, I assumed that if they'd survived long enough to pass a driving test and had enough intelligence to provide the means to buy a motorhome, that they wouldn't use a sledgehammer to crack a nut.

Is it a simplification too far? :lol: :lol: :lol: :lol: 

Kev :black:


----------



## raynipper (Aug 4, 2008)

Kev_n_Liz said:


> I was wondering if anyone had found this inverter guide of any use. Kev.


Oh yes Kev,
Especially now knowing a 500 watt halogen takes 500 watt... :idea:

And all those power tools as well as a lawnmower I can take with me... :wink: :wink:

Ray.


----------



## Pudsey_Bear (Sep 25, 2008)

Some of it was a bit tongue in cheek, you should have seen what was in the original list of assumed must haves when away.

Kev.


----------



## geraldandannie (Jun 4, 2006)

Kev_n_Liz said:


> Some of it was a bit tongue in cheek, you should have seen what was in the original list of assumed must haves when away.


You're right. I never cease to be amazed by what people what to take from home with them. I suppose it's as a result of our motorhomes becoming more comfortable, and being 'more like home'.

So far, about the only things we've needed 240V for when off hookup is for charging things. My new Mac seemed to be too much for our old faithful 150W inverter we've had for years, so I upgraded at Newbury to a £40 300W jobbie. I think that'll do for a while.

Gerald


----------



## Vennwood (Feb 4, 2007)

Wouldn't most people with larger inverters double up on appliances so charge the phone, laptop and camera batteries at the same time as say watching the TV or DVD?

We usually charge up small items during the day when the solar panels are in full flow.


----------



## Fatalhud (Mar 3, 2006)

sallytrafic said:


> I think you should have a new category of smiley face as well. Using a 3000W inverter to charge a 5 to 10W mobile phone charger (mines only 3W) will work but consume an awful lot of extra power so the faces could be orange after the 150W charger meaning it will do it but hey you will be wasting energy.


This is the problem I was having when I tried using the 1600w invertor already fitted in my van, It was using 45w just for the privilege of turning it on

The problem with the list I found is it was to general and inaccurate
Television wattage I assumed was old CRT because my LCD 19"telly only drags 45w, Games system way out, A new 360 or ps3 pulls way more wattage than quoted 
Then when you start quoting anything with a motor you have to take into account the start load and wiether the inverter can cope with it
Then theres the fact that 90% of the list is stuff you would never use in a Motorhome
But apart from that it was great :wink:

Alan H


----------



## raynipper (Aug 4, 2008)

Vennwood said:


> Wouldn't most people with larger inverters double up on appliances so charge the phone, laptop and camera batteries at the same time as say watching the TV or DVD?
> We usually charge up small items during the day when the solar panels are in full flow.


Yep, mee too Venwood.

My 1800 watt inverter came with the van as well as the 80 watt solar panel. So I keep the laptop, shaver, phone and digital camera always plugged into the inverter outlets for when I need microwave or toaster.

I know 5 or 10 mins heavy use won't put much back into the smaller items but every little helps. I also noticed the inverter took a few watts just at idle.

Ray.


----------



## Invicta (Feb 9, 2006)

Help!

Being in the middle of an inverter problem, (the one currently in situ in the R/V is whistling like mad right now and I have to move 3 vehicles to get to it to turn it off!) I would like to know how I can resize the graph above to enable me to read it. I have sent it to my pictures to see if I can enlarge it but with no success.


----------



## raynipper (Aug 4, 2008)

Hello Invicta,
Just click on the list (image) and it should enlarge.

I read on another post that whistling inverters could mean low volts on the batt. I guess you might leave your inverter connected or switched on all the time??

Ray.


----------



## Pudsey_Bear (Sep 25, 2008)

the list is far from complete, but not everyone who uses a inverter uses it in a MH, some use them at home these days or in a remote garage, so I tried to give some stuff that was useful away from the MH as well, as for the power consumption this does vary between the same type of appliance which Is why I put the wattage I was using, and not just TV etc.

At the end of the day if you have something that uses 1500watts, then a 2000watt inverter is really what you need, although depending on the appliance a 1500watt inverter might just manage for short periods. It's not rocket science, just a simple guide, and it's easy to find fault with it, but as time moves on each item on the list should hopefully use less power as things get improved.

When you buy something the wattage is usually on the box, if not sales people will usually let you open the box to see the power plate, microwaves are a bit different in that they use more power to boot up, all electrical gear should have a plate if not don't buy it.

Kev.


----------



## Vennwood (Feb 4, 2007)

Invicta said:


> Help!
> 
> Being in the middle of an inverter problem, (the one currently in situ in the R/V is whistling like mad right now and I have to move 3 vehicles to get to it to turn it off!) I would like to know how I can resize the graph above to enable me to read it. I have sent it to my pictures to see if I can enlarge it but with no success.


Hi Invicta,

When you say whistling like made is it the warning bell/whisle/buzzer that tells you it is either over loaded, over voltage etc.?

Do you have solar panels? If so do you have a Steca regulator? or maybe not even a regulator? I say this because I had a similar problem and eventually found out that if you connect the solar panel BEFORE the battery then the regulator doesn't know what battery is connected and so sends 16+ volts to the battery and then the inverter suffers from overvoltage and hence the buzzer/whistling etc.

Just a thought

Pete


----------



## Howlinwolf (Aug 25, 2008)

As someone who hasn't bought an inverter yet I have found your list very helpful. I can see immediately that a 150 watt one for the occasional use I have in mind would be more than adequate. Thanks.
David


----------



## Addie (Aug 5, 2008)

Its much more effecient to charge a laptop from a 12v laptop charger.

After all, you are taking a 12v DC source and steping it up to 19v in most cases, rather than taking a 12v DC source, changing to to 240V AC only to have a transformer taking it back down to 19V DC resulkting in lots of wasted energy.

http://www.maplin.co.uk/UNVERSAL_LAPTOP_CHARGER.search

You can also get 12v battery chargers (AA etc) or use the laptop charger to use with anything that might use a transformer.


----------



## raynipper (Aug 4, 2008)

Ellooo Kev,
Just a thought. I have always thought my solar panel attached to the roof of my Hobby was an 80 watt panel. But just measured it at 148cm X 66 cm and as far as I can see this relates to a 130 watt panel.

Dunno how accurate an assumption this is. Can't find any labels or indication on panel or controller. 

Ray.


----------



## Vennwood (Feb 4, 2007)

Following on with what Kev says you should also remember that as when deciding battery requirements etc. you should also decide on what you need an inverter to do. If you forsee only ever charging up a phone or using a TV then it makes sense to get one fit for the job. However if you think that down the line you may want to add a microwave for example then you need to plan for a larger inverter.

While I agree the larger the inverter the more power it will take just to run but at the end of the day running a 1500W inverter for a couple of hours even just charging a phone isn't going to flatten your batteries.

I think it more important to have the correct battery capacity to support it if you do decide on a larger inverter.


----------



## Vennwood (Feb 4, 2007)

raynipper said:


> Ellooo Kev,
> Just a thought. I have always thought my solar panel attached to the roof of my Hobby was an 80 watt panel. But just measured it at 148cm X 66 cm and as far as I can see this relates to a 130 watt panel.
> 
> Dunno how accurate an assumption this is. Can't find any labels or indication on panel or controller.
> ...


Hi Ray,

do you have any way of checking output, like a multimeter ?

Your sizes do suggest a 130W panel and if so should put out around 7 amps at midday or so at this time of year. You could measure the amps as it leaves the regulator


----------



## raynipper (Aug 4, 2008)

Vennwood said:


> Hi Ray,do you have any way of checking output, like a multimeter ? Your sizes do suggest a 130W panel and if so should put out around 7 amps at midday or so at this time of year. You could measure the amps as it leaves the regulator


Yup and thanks Vennwood.
I guess I could. But apart from this being 'work' and I try to avoid that as much as possible, the regulator does show volts and amps output.

I will check once out of the barn and shade. I will assume it's a 130 panel. As they say "Ignorence is bliss" and I'm happy. 
It certainly tops up the leisure batteries again after giving them a 10 minute pasting with the microwave.


----------



## Invicta (Feb 9, 2006)

Thanks Kev and everyone who responded to my re sizing problem-I have now been able to read it.

The whistling noise coming from the inverter is due I expect to the inverter being overheated - well at least that was what was showing last weekend when it whistled. We are about to move the R/V out to get to the inverter to switch it off. Meanwhile my super duper auto electrician is coming next week to check it out. At the present time I have a 12x1000 inverter fitted. I recently had three new Victron 100amp batteries fitted so their condition should be OK though I have disconnected everything including the hook up until I can get to the inverter to switch it off and they may have run down (?).
************************************************************************************************************************
Just been out to switch off inverter-guess what? The whistling noise had stopped! Suspect it was due this time to a low battery as the carbon monixide alarm was flashing red-also a sign, according to the panel, of a low battery. Have now switched the inverter off as I understand that it uses power even when no electrical equipment is in use.


----------



## Pudsey_Bear (Sep 25, 2008)

raynipper said:


> Ellooo Kev,
> Just a thought. I have always thought my solar panel attached to the roof of my Hobby was an 80 watt panel. But just measured it at 148cm X 66 cm and as far as I can see this relates to a 130 watt panel.
> 
> Dunno how accurate an assumption this is. Can't find any labels or indication on panel or controller.
> ...


Hi Ray,

The controller will not have any info re the panel in most cases, the panel info is usually on the back of the panel itself.

The technology of panels changes over time like everything else, and I am in no way expert enough to comment on the possible output of your panel, I wish I was, but you need someone more conversant with Solar stuff.

Sorry I couldn't be more help, I'm still learning a lot of stuff, I just repaired my own fridge though, with the kind help of Philthefridge, (diamond geezer).

Kev.


----------



## sallytrafic (Jan 17, 2006)

My 130W panel is the size of 50W panels I was buying 5 years ago (bought well over 1000 for various projects)


----------



## raynipper (Aug 4, 2008)

Hummmm, now I really am confused.
So as always when presented with a difficulty I will go off and find some other project that I can master like which Bordeaux to open.

Just been for a look round St. Mere Eglise. The whole place is packed with people in new repro uniforms of all nations smelling of mustiness and cardboard boxes. 

The main square has many cheap French food tents and long queue's of military looking personel with plastic beer in hand waiting to get served. Bit of a carnival atmosphere where the locals are cashing in on the last big date.

Ray.


----------



## Pudsey_Bear (Sep 25, 2008)

I've now wired in the inverter, it's under the front passenger seat out of the way and close to one of the leisure batteries, When we got this MH a previous owner had put in four extra sockets, two on each side, so I have now re-wired two of them to run from the inverter (600watt), we also have a smaller 300watt one for when we need to just charge something up.

However while typing this, I wondered what would happen if I wired in the 300 watt inverter into the the same two sockets as the 600watt, would that then give us 900 watts, or would it be a disaster, it would be easy enough to do, I could just put a 13amp plug onto both ends of a short piece of cable.

Someone inform me before I blow up the MH.

Kev :wave:


----------



## Pudsey_Bear (Sep 25, 2008)

Deleted because of Double posting

Kev :wave:


----------



## sallytrafic (Jan 17, 2006)

First of all Kev using two plugs and a piece of cable to bridge two sockets is in itself dangerous and prohibited. When one end is plugged in the pins of the other end could be live. Yes I know you would *never* do it powered up.

Next, although two inverter outputs can under certain circumstances be joined up they have to be synchronised ie they both have to have the ac output passing through zero at the same time. Also they have to be designed to do that. If instantaneously one was trying to put out its peak positive voltage whilst the other one was trying to put out zero or its peak negative volts you can see that it wouldn't work.

The most likely outcome will be one or two broken inverters with fire and electrocution also possible.


----------



## Pudsey_Bear (Sep 25, 2008)

I figured it wouldn't work, but wasn't sure why, not being a sparky, it is similar to a domestic ring main in one sense, having cables running from one socket to another and being fed from both ends, but obviously synchronised, as it's the same power source.

I had to ask on the off chance that it would work, and I would have increased power if needed, the other reason was if it would have worked I could have hard wired in the 300watt, and chose which I needed at that time. but to do it now would invoke disaster, as I would be sure to turn on No 2 while No1 was still live.

Thanks Frank once again.

Kev :wave:


----------



## SineadandTony (Jul 22, 2009)

Have more or less decided on a 1000/1100 watt inverter and just wondered does anybody have a preference on make model etc. Have looked at Ring which can be purcased on E-Bay for about £140. A remote control can also be purchased for this which means that access is not really an issue. Any advice would be greatly appreciated.

Tony


----------



## Pudsey_Bear (Sep 25, 2008)

SineadandTony said:


> Have more or less decided on a 1000/1100 watt inverter and just wondered does anybody have a preference on make model etc. Have looked at Ring which can be purcased on E-Bay for about £140. A remote control can also be purchased for this which means that access is not really an issue. Any advice would be greatly appreciated.
> 
> Tony


I was going to get one of these I decided I didn't really need all that power, but wish I'd got one in the end, as I plumped for a 600 watt version and it's not really of any use, but it's cabled up for the bigger one anyway.

See my thread on the subject, some excellent advice given by some very bright people last page is relevant

also last post very relevant re fuses click

this whole thread is mostly relevant too

Good luck.

Kev


----------



## tramp (May 25, 2005)

get you ass on to maplin site,

we just bought a 1000w modified invertor with dual outlet plugs and a remote control for £100 inc postage.

Absolutly first class and the only thing different to our old Waeco one is there`s no option to connect invertor to mains, but then again WHY do that :?: :roll: 

You can mount it next to the batteries and run the remote upto 5mts away, just press switch to turn on and off no more lifting seats etc, and just run a correct amp cable to another flush fiited plug socket in the camper for a dedicated invertor socket. 8) :lol: :lol:


----------

