# Inverter - is it big enough?



## timotei (May 4, 2007)

I have a 150watt inverter.

I want to run television - 60w, sky + box - 40w and a fan - 35w...at 135w am I too close to the maximum? The inverter was very hot yesterday with just the tv and digibox plugged in. Would you advise moving up to a 250w or similar?

Thanks,

Timotei


----------



## raynipper (Aug 4, 2008)

timotei said:


> I have a 150watt inverter.I want to run television - 60w, sky + box - 40w and a fan - 35w...at 135w am I too close to the maximum? The inverter was very hot yesterday with just the tv and digibox plugged in. Would you advise moving up to a 250w or similar? i


Hello timotei,
Is that a shampoo???

My van came with an 1800 watt inverter and I'm very glad it did. Just like a spare wheel very handy when you need it.

I would not mess about slightly upgrading just a few watts but get something usable. As you have found out with 135 getting hot. OK you might not see yourselves using a 1000 watt microwave just yet but handy as and when you do.

Ray.


----------



## timotei (May 4, 2007)

Ray,

if you knew how much hair I have you'd know there's no need for Shampoo anymore!!!

Timotei


----------



## averhamdave (May 21, 2005)

Mmm and if you do that fit a few more leisure batteries as well. Do you really need to microvave your dinner if not on hook up?

I ran my TV and Sat Box off a 150w inverter without a prob before upgrading everything to 12v. 

A 150w inverter runs at 150w continious and if of reputable manufacture will handle spikes of double that, ie 300w so you should be fine.

Coming back to the 1800w inverter, can I ask what size cable and inline fuse you are running with that? Wow!


----------



## raynipper (Aug 4, 2008)

timotei said:


> Ray,if you knew how much hair I have you'd know there's no need for Shampoo anymore!!!


Ha ha...  
My wife gets jealous when my old gray hair starts to curl as it gets longer and cuts it short. So I use less and less shampoo. 

Ray.


----------



## raynipper (Aug 4, 2008)

averhamdave said:


> Mmm and if you do that fit a few more leisure batteries as well. Do you really need to microvave your dinner if not on hook up? I ran my TV and Sat Box off a 150w inverter without a prob before upgrading everything to 12v. Coming back to the 1800w inverter, can I ask what size cable and inline fuse you are running with that? Wow!


Yep and yep again. My culinary expertise is frozen dinners for one straight out of the freezer and into the microwave.

But then I don't have a sat and my TV is 12v.

The 1800 watt inverter is positioned beside the two 130 amp leisure batteries under the settee. So the cables I assume supplied with the inverter are similar to starter leads and only 18" long. Don't know the metric size but big.

This inverter powers my low wattage appliances like laptop, mobile phone and shaver quite happily also. But I only leave it switched on for the time needed.

I still say over capacity is better than stretching it.

Ray.


----------



## DABurleigh (May 9, 2005)

Read the MHF inverter FAQ.

Inverters are efficient (>90%) running between 50% and 100% of their maximum continuous rating. They are horribly inefficient when running at a mere fraction of their continuous rating.

The corrollary is that if you are running near a 150W continuous limit and it is getting hotter than a mere 15W heat dissipation would suggest, perhaps you have a fault or a very poor inverter.

Dave


----------



## timotei (May 4, 2007)

Dave,

I was going to PM you, but felt this mighr be of interest to others. I have previously read your excellent FAQ section, and re-read it after your reminder in the above post. However, I am a complete no-hoper when it comes to elctrical matters! Sorry!

Yesterday I bought a plug in power monitor from Maplin so I could accuratekly gauge the power consumption etc of the items I want to use on the inverter, and I also bought a 300w inverter, feeling that this would allow us to use all our expected items, along with phone chargers etc at the same time if required.

According to the power monitor, the TV draws approx 45 - 55w, and the fan 30 - 35w. On both the 150w and 300w inverter, this is enough to trigger an alarm when the power meter is plugged in, but both inverters run fine when the power meter is out but the 2 items are plugged in.

As stated above, I am an electric idiot! Can you explain in words of 1 syllable why this is?

Also, is it true that the power rating for these inverters is only accurate when connected directly to the leisure battery, and that it is halved when plugged invia the 12v "ciggie lighter" socket in our hab area?

thanks for your help, feel slightly embarrassed to have to ask, but I guess that's why we pay our tenner......for the reassurance of the experts!

Timotei


----------



## DABurleigh (May 9, 2005)

Is the alarm coming from the power meter or the inverter? Your power meter will expect a smooth sine wave, and probably assume it has one in order to calculate the RMS power.

"Also, is it true that the power rating for these inverters is only accurate when connected directly to the leisure battery, and that it is halved when plugged invia the 12v "ciggie lighter" socket in our hab area? "

Not strictly true, however if your battery to 12V socket wiring is inadequate (MANY are) then the voltage at the inverter input can easily be below its required threshold when drawing only a fraction of the power the inverter can handle, and yet the inverter gives a low voltage alarm.

Dave


----------



## clodhopper2006 (Aug 13, 2006)

DABurleigh said:


> Not strictly true, however if your battery to 12V socket wiring is inadequate (MANY are) then the voltage at the inverter input can easily be below its required threshold when drawing only a fraction of the power the inverter can handle, and yet the inverter gives a low voltage alarm.
> 
> Dave


And i suspect that's the case here. You can loose half a volt per meter in thin wiring depending on the current drawn so you may find yourself dipping way below 12v with just the load you descibe even with a fully charged battery close to 13v


----------



## timotei (May 4, 2007)

Thanks Dave / Clodhopper,

It seems to be the inverter alarm sounding. It is the factory fitted 12v socket back in the hab area I am using.....I see you have an Autotrail CH, have you had any similar issues with yours?

Is there any easy way around this?

Timotei?


----------



## teensvan (May 9, 2005)

Hi.

We started off with a 300 watt inverter but found it was not happy when run close to it's max. We now have an 800 watt one which is fine. It is wired in on the 12 volt side with 16mm cable via an isolator and 50 amp fuse.

steve & ann. --------- teensvan


----------



## Invicta (Feb 9, 2006)

I have just sent my first ever advert on this site (an inverter) for approval. Is it usual to include the cost of postage or should that be included in the asking price?


----------

