Basic Electrical question (1 Viewer)

Apr 25, 2016
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Hi, we are new to the MH scene, and are awaiting the delivery of our MH at any time now.
The one thing that does confuse me are electrics.
We intend to do a fair bit of wild camping, so have ask the dealer to install a second leisure battery, and may consider solar panels, depending on how we get on.
After reading up on several threads, we keep comming accross the term Inverter.
Please could someone please explain in very simple terms what an inverter is, and what they do.
Many thanks.
Nigel.
 

pappajohn

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An inverter converts (inverts) 12vdc (battery) voltage to 230v (mains) so you can run mains operated equipment on a 12v system.
There are many variables with inverters.
They are power hungery, needing many times more amps than the appliance actually needs to work.
Cable size depends on power needed but could be as big as 25mm sq.
 
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Nigel L
Apr 25, 2016
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Ok, thanks for the replies, so are you saying that in reality, that they aren't really feesable, as they will draw more power than you actually need to run the other appliance etc?
 
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mjltigger

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Ok, thanks for the replies, so are you saying that in reality, that they aren't really feesable, as they will draw more power than you actually need to run the other appliance etc?
Some would say that, others would say you can't travel without one. It is up to what you need. We gave a small inverter and 200AH of leisure battery, no solar and we can manage a weekend without mains no problem.

If you need longer, have less battery or want to run hairdryers or microwaves then your needs are different and you would need a big inverter and big batteries and some method of charging them etc.
 
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pappajohn

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The most important thing with inverters, you have to be able to quickly replace back into battery the amps used by the inverter.

If an appliance uses 240watts per hour ro work your battery needs to be able to provide 20amps per hour....not a problem but......
You now need to replace that 20amps each hour to keep your battery topped up.
The more hours it isnt topped up means it gets flatter ad the inverter uses the battery reserve power, which in turn gets harder to replace in a given time.
 
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Old Soldier

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Although we have a small inverter, in over 20 years motorhoming we have never used it! Use hookup when available, when not then use 12v and gas.... Have a solar panel to help top up battery and have a gas kettle for hot drinks. Use gas or BBQ to cook with and use a duel voltage cool box sparingly whilst running fridge on gas. Change light bulbs to LED and buy a couple of stand alone LED light units in case of emergency or if low lighting is required. Top up battery when driving out for the day. We have a duel voltage TV and satellite tuner and can manage at least 4 days of normal use of all systems on non hook up site or whilst wild camping. Good luck with your touring.

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Jan 8, 2013
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They are power hungery, needing many times more amps than the appliance actually needs to work.

but it will also convert your 12V to useless in a few minutes (well maybe an hour)


I would not agree with either of those statement. A small amount more maybe.

Ok, thanks for the replies, so are you saying that in reality, that they aren't really feesable, as they will draw more power than you actually need to run the other appliance etc?

They use a small amount more because of the inverter losses. About 1A more
Myself and many others on here wouldn't be without one, they give you so much more flexibility and 240 TV's ect are so much cheaper.
I have had one on boats and campers for almost 20 years.
I'm afraid many people are frightened to death about using too much battery power, I wont be governed by my battery's.
I have 2 x 120A battery's and solar panels and never have a problem. Just don't expect to use any appliance with an heating element.
I would guess that a 12V TV will take 5A, my 240V TV will be 6A.
I turn my inverter on to watch TV in the evenings for often over 3 hours. The battery are always fully re-charge the next day.
 
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Feb 24, 2013
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not long enough
I would not agree with either of those statement. A small amount more maybe.




I would guess that a 12V TV will take 5A, my 240V TV will be 6A.
I turn my inverter on to watch TV in the evenings for often over 3 hours. The battery are always fully re-charge the next day.

I am no expert, but you may be guilty of using numbers to support your own logic, bit like the calor gas / refillables suddenly calor is 50% more expensive

My MH has a display showing Amps being drawn, probably not totally accurate, but our 12V LED TV's are around 2A each :)

but you are definitely right on price (y)(y)
 
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Aug 6, 2013
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The difference between mains TVs and 12v TVs in many cases is the supplied PSU. Remove it and suddenly you have a (reasonably priced) 12v TV.

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Dec 12, 2010
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We have a smallish inverter (600 w) that we use to charge the electric bike batteries, everything else runs on 12 volts or gas (y)
 
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Mar 10, 2016
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Three years and counting, 30 years a tent tower.
there are definitely different ways to run things

hair driers seem to be the sticking point though,
and nesspresso machines:LOL::LOL:

@Nigel L several users have explained what the inverter does but don't be too put off them. They have their uses.

You are better running things directly off battery power where you can, as others have stated.
An inverter does lose some of your available battery power in the process of turning your battery DC power into AC power at 230v. Good top quality modern inverters such as the Victron Phoenix range can achieve efficiencies of 92% (you lose 8% of what you put into them, its not a fixed amp figure). However that efficiency level drops the more load is applied.

So if you have something essential (usually to your better half) that only runs off 230vAC, which in my experience tend to be hair dryers (battery ones seem to be pretty rubbish) or Nesspresso machines :):) then bite the bullet and run them the minimum time possible, just don't leave them switched on!
The other factor to think about is the type of equipment you want to run on AC. Some sensitive equipment won't run well (or possibly at all) on non-sine wave inverters, but pure sine wave inverters are more expensive.

Add as much solar as you can fit and match them to as much battery capacity as you can to extend your off grid time as much as possible.

We have a smallish inverter (600 w) that we use to charge the electric bike batteries, everything else runs on 12 volts or gas (y)
Me too! and the other big inverter for that :swear::swear::swear::swear: Nesspresso machine :ROFLMAO::ROFLMAO::ROFLMAO:
 
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funflair

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If you want an inverter get one BUT understand what you can do with it, how much it will take out of your batteries and how you are going put to it back in.

Whatever amps it says on the back of a microwave, coffee machine or hair dryer it will take about 20 times that in amps from your batteries via the inverter, for example 1200 watt coffee machine will be about 5 amps so take about 100 amps from your batteries, for an hour this would kill them BUT for two minutes is only 30th of an hour so less than 4 amps per hour so as long as you have solar or whatever to put this back "no problem".

We have 320 watts of solar and can make between nothing and 20 amps charge, nothing would take forever to recover your depleted batteries but 20 amps will take next to no time.

Understand your system and enjoy.

Martin

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pappajohn

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pappajohn said:
They are power hungery, needing many times more amps than the appliance actually needs to work.

I would not agree with either of those statement. A small amount more maybe.
Why would you disagree with my post ?

If an appliance is rated 240watts it will consume, near enough, 1 amp @ 230v
The same appliance will consume around 20 amps @ 12v...plus conversion losses.

Ergo....power hungry needing many more amps to power the same appliance.
 
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etap

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Hi NL.
Not an answer to your original question but, each MH we buy always has a solar panel which will charge the engine and leisure battery, this is particularly useful in the winter when MH has little use, the batteries are always fully topped up, we only have a 100 amp leisure battery and we mostly use campsites with elect, hook up.
If you are going to wild camp for a night at a time then you should be ok with an inverter as long as you are sensible about usage and have a solar panel, the problem comes when you wild camp for a few nights at a time, then you really need to be careful as to what you use, members here do wild camp often but they do have lots of battery power and probably only use the inverter for the tv (we don't have one).
Good luck with your new MH.

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funflair

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Why would you disagree with my post ?

If an appliance is rated 240watts it will consume, near enough, 1 amp @ 230v
The same appliance will consume around 20 amps @ 12v...plus conversion losses.

Ergo....power hungry needing many more amps to power the same appliance.
Yes but they are different amps, the overall efficiency is only marginally lower.

Martin
 
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Nigel L
Apr 25, 2016
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Thanks for all the replies, they have been very useful, and even I understood them
Basically, the items we would want to use, are as mostly mentioned above, ie, hairdryer for the goodlady Electric shaver, phone charge and I-pad charging.
We will be getting solar panels fitted, so with two leisure batteries, and minimal use of an inverter for the items listed above, we should be ok?
 
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pappajohn

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Yes but they are different amps, the overall efficiency is only marginally lower.

Martin
An amp is an amp regardless of voltage or ac/dc

The only non variable in the conversion is watts
If it needs 100 watts to run, it needs 100watts, regardless of voltage.
the supply voltage dictates amps used to attain that 100watts......the lower the volts, the higher the amps.
It isnt the appliance using more amps...a 2amp tv will still use 2amps......its the inverter which consumes the higher amps in the conversion from 12vdc to 230vac.

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As others have said, if your budget can stretch to it, then the only safe kind of inverter to buy is a 'pure sine', the far less expensive 'modified sine' inverters can and will stuff quite a lot of different types of equipment, including toothbrush chargers, lap-tops etc.

My self built van has only 1 x 150 AH leisure battery and a single 150 watt solar panel and we have never had any problems with power to date, but mind you in the evening we play scrabble or cards or even read and we never use a TV, so our power consumption is very considerably less than a lot of people.

Phil
 
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Jul 5, 2013
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Thanks for all the replies, they have been very useful, and even I understood them
Basically, the items we would want to use, are as mostly mentioned above, ie, hairdryer for the goodlady Electric shaver, phone charge and I-pad charging.
We will be getting solar panels fitted, so with two leisure batteries, and minimal use of an inverter for the items listed above, we should be ok?
Your needs are very similar to ours. You only need the inverter for the hairdryer. It does not have to be pure sine wave for that type of appliance. Wife uses a 1200W travel type hairdryer that works just fine.

The phone and ipad charging uses USB at 5V so just get a 12V USB charger that goes into the ciggy lighter type socket. That is what we use for wife's ipad and iphone and my Android phone and tablet. Wife reckons they charge her ipad quicker than the 240V charger she has. What shaver do you have? I have a Philips and have got a 12V charger for it . All you need are a couple (or even one) ciggy lighter sockets fitted that run off the leisure batteries. Or you can use a Hella type 12V unit and then buy adaptors for that. You can DIY or get a dealer to fit either of these.

We also use an electric toothbrush, which needs a more expensive type of inverter (pure sine wave). The way round that is to buy the version that uses 2 x AA batteries rather than being rechargeable.

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funflair

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An amp is an amp regardless of voltage or ac/dc

The only non variable in the conversion is watts
If it needs 100 watts to run, it needs 100watts, regardless of voltage.
the supply voltage dictates amps used to attain that 100watts......the lower the volts, the higher the amps.
It isnt the appliance using more amps...a 2amp tv will still use 2amps......its the inverter which consumes the higher amps in the conversion from 12vdc to 230vac.

Yes.

But if all you have is 12 volts as your power source it matters little between taking 20 amps at 12 volts or 1 amp at 240 volts via your inverter, other than some small conversion efficiency it pulls the same from your batteries.

Martin
 
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pappajohn

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Yes.

But if all you have is 12 volts as your power source it matters little between taking 20 amps at 12 volts or 1 amp at 240 volts via your inverter, other than some small conversion efficiency it pulls the same from your batteries.

Martin
Whooosh !

Straight over my head making no sense whatsoever.
 
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magicsurfbus

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We bought an inverter but never used it, so it's been removed. We run everything we need on the 12v system, after converting all the light fittings to LED. Unless you want to use power hungry gadgets like air conditioning you could probably manage for most of the year on one leisure battery and a solar panel. On a typical 3-4 week trip to France we'll rarely if ever use mains electricity.
 
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