# Is this inverter suitable??



## pmcclure (Dec 6, 2011)

I know questions similar to this have been asked before, so apologies for asking.

The wife would like me to fit an inverter in the motorhome to run for example
a slow cooker 265w to be used whilst driving
a george foreman 700w to be only used when stationary
charging a mac book

We have fitted: 2 x 110 amp leisure batteries and a large solar panel (dont know wattage)

I'm thinking of one of these Link to inverter

Would it be suitable? and would I need an inline fuse from the batteries to the inverter?

It would be fitted in the motorhome, but within 1metre of the batteries.

Thanks

Peter


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## VanFlair (Nov 21, 2009)

Hi Peter

If the equipment you want to run has electronic controls they might not like the inverter if it is not pure sine wave, I know this because our coffee machine would not run on the old inverter but loves the new pure sine one.

Yes you will need a fuse inline from the batteries.

Running the grill at 700 watt! this will depend on how long you want to run it for as it will pull something close to 80 amps from your batteries.

Our 2000 watt inverter runs 1200 watt coffee machine from 2x85ah but it only runs for 20 seconds or so to make an espresso, likewise microwave for a few minutes is OK.

Martin


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## peribro (Sep 6, 2009)

I have exactly the same inverter and have had no problems connecting a number of different appliances and devices, including a microwave and a hairdryer running at 700W. You will need to use a 200A fuse in an appropriate fuse holder. Details are on Sterling's website here.


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## Pudsey_Bear (Sep 25, 2008)

pmcclure said:


> I know questions similar to this have been asked before, so apologies for asking.
> 
> The wife would like me to fit an inverter in the motorhome to run for example
> a slow cooker 265w to be used whilst driving
> ...


Hi Peter,

As a rule of thumb, you need to double your wattage with an inverter as you will have a surge when you turn anything on, so your needs imply a need for a 2kw inverter, to give a little spare capacity, as that's a bit on the big side I'd recommend a small ciggy socket 150w for phone charging, laptop etc, and perhaps a 300w for running the TV, you pay a little more for the tackle, but don't have the high running costs of the bigger inverters.

The type of inverter is difficult as some things will run fine on square wave, others on modified sine wave, while others won't play on anything less then pure sine wave, so you need to know a bit more about running on an inverter before diving in, I'll bow out there as we never used those items on an inverter.


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## peribro (Sep 6, 2009)

I agree with what Kev says about peak outputs but you will see from Sterling's datasheet on the 1,000W inverter, that it is able to cope with peak outputs of up to 2,000W.


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## andrewball1000 (Oct 16, 2009)

Peter, I run a small hairdryer on low setting and a 750w toaster on a 1000w (non sine wave) inverter. However these are for short periods only and I question a grill or SLOW cooker. I suggest you do the maths to see what they will draw. The solar will not replace at the same rate as you use it.


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## VanFlair (Nov 21, 2009)

The OP did say the slow cooker while travelling and the wattage is not that high at 265 so might pull about 50 amps off the alternator, not sure if this is OK but I guess so, check alternator output.

Martin


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## Pudsey_Bear (Sep 25, 2008)

Before choosing check out this site it might help, also this thread I started a long time ago gives a lot of info.


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## andrewball1000 (Oct 16, 2009)

VanFlair said:


> The OP did say the slow cooker while travelling
> 
> Martin


yes, sorry I missed that. It was the grill when stationary that scared me. 700w/12v = 60 amps. How long does it take to warm up and cook?

Microwaves and toasters are quick.


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## selstrom (May 23, 2005)

VanFlair said:


> The OP did say the slow cooker while travelling and the wattage is not that high at 265 so might pull about 50 amps off the alternator, not sure if this is OK but I guess so, check alternator output.
> 
> Martin


More like 25 amps


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## Mrplodd (Mar 4, 2008)

I use my slow cooker frequently when travelling (not sure of the wattage but its only a little cheapie from Argos.) The alternator provides more than enough current and its really nice to have a hoy meal on arrival.

HOWEVER running your grill will take a LOT out of your leisure batteries. Dont forget that you may well want to run a TV, lighting etc AFTER you have used it. I would suggest you either forget that idea or buy a cheap generator as your leisure batteries will take a hammering !!


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## listerdiesel (Aug 3, 2012)

The only passing comment I'd make is that nowhere do Sterling Power quote the efficiency of the inverter, so guesstimates of the 12V loading of the battery are just that.

If you assume 90% efficiency, that equates to just under 1700W at a nominal 12V for full output. In real terms that is 142A when flat out, not quite pro-rata for other, lower loadings, but close enough.

You cannot just use the output power divided by the input voltage to calculate current draw, you need to know the input power first, so (Output power/Input power) X 100 = Efficiency

(1500 / 1700 ) X 100 = 88% as an example.

You can also work it round the other way if you know two of the variable.

Cable sizes need to be suitable, and fusing fitted. I'd suggest 35mm or even 50mm welding cable for that loading. Better to go slightly over the top than under, although the cables shown in the picture don't look a lot bigger than 10mm or 16mm! 

Peter


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## VanFlair (Nov 21, 2009)

Hi Selstrom

You are closer, too much safety margin in my maths I think.

Martin


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## pmcclure (Dec 6, 2011)

Thanks for all the replies. 

I'm going to order the inverter and inline fuse first thing Monday morning, and have suggested to the wife that using the inverter to power the George foreman isn't a good idea.

The inverter is going to go in a cupboard which isn't really accessible so will use the remote on/off switch to isolate it. 

Is it ok to plug in an extension lead that has a wall mounted socket on the end as shown in the photo?


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## listerdiesel (Aug 3, 2012)

That should be OK. 

Peter


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## WildThingsKev (Dec 29, 2009)

Also bear in mind that when you draw a high current you reduce the effective capacity of the battery as per diagram below in which a typical lead acid battery is the yellow curve. You can see that if you draw 33A from a 120Ah battery that you will only get 60Ah out of it, and that is to totally flat so you actually only get about 30Ah usable (to 50%).

I can't remember where I downloaded the diagram from but it was undoubtedly a "very interesting" website. The yellow curve may represent a starter battery rather than a good quality leisure battery and I think an AGM battery is close to the top curve.


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## pmcclure (Dec 6, 2011)

The inverter has just been ordered.

Now I need an inline fuse. Have seen this one on ebay http://www.ebay.co.uk/itm/400395506483?clk_rvr_id=457026622060&afsrc=1 It says O gauge cable only.

How do I find out what size cable the inverter comes with?

Would prefer to order from the UK as I'm away on my travels from easter Monday.


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## peribro (Sep 6, 2009)

Looking at the picture I think that the fuse holder would be able to accommodate the cable. I bought this fuse holder and this fuse for my inverter, although obviously more expensive than the one you have found. I recall having read somewhere that gold plated fuses and fuse holders are somehow better than others - but they probably say that about anything that is gold plated!


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## pmcclure (Dec 6, 2011)

Found this on the Sterling web site showing the model number of the fuse holder for the cable size http://www.shop.sterling-power.com/acatalog/QSW.pdf

Make you wonder why they dont add a few quid onto the price and include the fuse holder which is suitable for the inverter


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## ceejayt (Nov 25, 2005)

Hi All

I have TWO teleadaptor inverters which plug into a cigarette style socket which I had for use when I was travelling on aeroplanes. They are specifically designed to power any laptop computer.

They are FREE to a good home - just PM me if you wamnt one. Postage cost onkly would be appreciated - just dont want to throw them away.

Chris


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## pmcclure (Dec 6, 2011)

Hopefully the new inverter will arrive today.

When I connect it to the leisure batteries (2 x110) should I?
1) connect the + and - to just one battery
2) connect the + to one battery and - to the other
3) it dosn't matter

Thanks in advance for all replies

Peter


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## listerdiesel (Aug 3, 2012)

As long as the cabling between the two batteries is heavy enough, it doesn't matter, assuming they are both the leisure batteries.

Peter


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