Hi all, A bit of advice please. Been thinking about buying an inverter, but I dont really know what to look for. I know what they do, but how well do they do it ?
Whats the minimum spec that anyone would recommend ?
Steve
Inverters
Moderators: Doone, westonwarrior
-
wooden wheel
- Bongolier
- Posts: 211
- Joined: Sun Nov 26, 2006 7:04 pm
- Location: Liverpool
-
haydn callow
- Supreme Being
- Posts: 5777
- Joined: Mon Jan 08, 2007 9:50 pm
- Location: Somerset
- Contact:
Depends what you intend to run. If you want to run a mains TV you need a good pure sine wave inverter. For charging laptops etc it's not so important. Whatever you get don't think you can have unlimited mains electric, a electric kettle will flatten your battery in mins. You get what you pay for with inverters, mastervolt are very good. I would suggest a 250watt quality inverter. This would cover most needs. Make sure it has a voltage sensor cutout to protect your battery from discharging to the point it gets damaged.
-
timhum
Hi Steve,
Darn it, I just typed a wordy reply and it got lost in cyberspace!
This is a shorter reply but just as friendly I hope.
Go for a modified sine wave type of inverter and for your minimum spec, add up the wattages of all the devices you might have on at the same time and add a decent margin, say 50%. This is the Continuous power that the inverter will have to supply. Ignore the Surge power figures where given on the inverter spec, they can be optimistic and anyway all inverters have some sort of surge capacity. If in doubt, go for the next size up, it might only add 30 quid to your cost but it will be bombproof for your application.
If the inverter is going to be in an awkward place to switch on, choose one with a remote switch, you could mount it on the dash for convenience.
Inverters are very efficient, 85 to 90 % is common and using a big one to only recharge your electric toothbrush will not change those high figures.
Hope this helps, any more queries?
All the best,
Tim
Darn it, I just typed a wordy reply and it got lost in cyberspace!
This is a shorter reply but just as friendly I hope.
Go for a modified sine wave type of inverter and for your minimum spec, add up the wattages of all the devices you might have on at the same time and add a decent margin, say 50%. This is the Continuous power that the inverter will have to supply. Ignore the Surge power figures where given on the inverter spec, they can be optimistic and anyway all inverters have some sort of surge capacity. If in doubt, go for the next size up, it might only add 30 quid to your cost but it will be bombproof for your application.
If the inverter is going to be in an awkward place to switch on, choose one with a remote switch, you could mount it on the dash for convenience.
Inverters are very efficient, 85 to 90 % is common and using a big one to only recharge your electric toothbrush will not change those high figures.
Hope this helps, any more queries?
All the best,
Tim
-
dandywarhol
- Supreme Being
- Posts: 5446
- Joined: Mon Dec 19, 2005 10:18 pm
- Location: Edinburgh
-
francophile1947
- Supreme Being
- Posts: 11354
- Joined: Mon Dec 18, 2006 6:15 pm
- Location: Norwich
-
Dave up north
I wouldnt use less than 600W. I have a 300W and its pants.
This one from Maplins is a bargain in my humble opinion Less than 40 quid
http://www.maplin.co.uk/Module.aspx?Mod ... R&doy=13m6
-
Lovejoy
I have a baby 150w one.
It struggles to run my laptop if the laptop battery is charging at the same time. But if I charge the battery up at home first, then plug it in via the inverter it runs for hours no problem.
It can't handle a 40w light bulb - it lights it up but not very bright. There is probably a good scientific reason for this but I'm not clever enough to understand why.
Two pieces of advice I would give:
1. Go for a 'silent' one if you can. I don't know if they all have fans in them, but I tried two. The first was very noisy, and as the fan runs even when nothing is running from it. So if you have it connected all the time the noise is going to get on your nerves. It may seem quiet at first, but that steady hum gets annoying.
I don't know if you can get a completely silent one, but some seem to make more noise than others.
Where you mount it is also going to impact how noisy it is due to vibrations.
They get noisier the more power you draw from them as the fan speeds up.
2. As I understand it, they draw a small current (2 amps or so) even when nothing is connected to them, so ideally you need to be able to switch it on/off as and when you need it.
I did this using a four way 12v socket from Halfords with a remote switch block to control each of the four sockets.
The four way outlet is hidden away behind my kitchen unit (along with the inverter), and the remote switch box is mounted on the side of the kitchen unit. So I can switch off the inverter.
To make things neater and hide the inverter, I took a short length of cable from the 3 pin plug plugged into the inverter, to a 3 pin socket mounted to the side of the kitchen unit. They do some nice neat ones in C.A.K Tanks (.co.uk).
This way the inverter is hidden from view, it is switchable from the remote switches, and you have a decent looking 3 pin socket to plug things into.
If I was doing it all again, I would probably go for a 300w minimum, and get the quietest one I could find - although most shops I found were not able to plug it in to see how noisy it was, and were unwilling to take it out of the packaging to let me take it to the van to try it.
My local motor factors proved to be the most helpful in the end, but I am a bit of a regular there.
Does anyone know if there is such a thing as a completely silent inverter ??
It struggles to run my laptop if the laptop battery is charging at the same time. But if I charge the battery up at home first, then plug it in via the inverter it runs for hours no problem.
It can't handle a 40w light bulb - it lights it up but not very bright. There is probably a good scientific reason for this but I'm not clever enough to understand why.
Two pieces of advice I would give:
1. Go for a 'silent' one if you can. I don't know if they all have fans in them, but I tried two. The first was very noisy, and as the fan runs even when nothing is running from it. So if you have it connected all the time the noise is going to get on your nerves. It may seem quiet at first, but that steady hum gets annoying.
I don't know if you can get a completely silent one, but some seem to make more noise than others.
Where you mount it is also going to impact how noisy it is due to vibrations.
They get noisier the more power you draw from them as the fan speeds up.
2. As I understand it, they draw a small current (2 amps or so) even when nothing is connected to them, so ideally you need to be able to switch it on/off as and when you need it.
I did this using a four way 12v socket from Halfords with a remote switch block to control each of the four sockets.
The four way outlet is hidden away behind my kitchen unit (along with the inverter), and the remote switch box is mounted on the side of the kitchen unit. So I can switch off the inverter.
To make things neater and hide the inverter, I took a short length of cable from the 3 pin plug plugged into the inverter, to a 3 pin socket mounted to the side of the kitchen unit. They do some nice neat ones in C.A.K Tanks (.co.uk).
This way the inverter is hidden from view, it is switchable from the remote switches, and you have a decent looking 3 pin socket to plug things into.
If I was doing it all again, I would probably go for a 300w minimum, and get the quietest one I could find - although most shops I found were not able to plug it in to see how noisy it was, and were unwilling to take it out of the packaging to let me take it to the van to try it.
My local motor factors proved to be the most helpful in the end, but I am a bit of a regular there.
Does anyone know if there is such a thing as a completely silent inverter ??
-
Dave up north
The one I listed states "quiet" operation.
Never heard of a powerful silent one. My 150W one, that I never use coz its rubbish is silent, but the powerful ones generate heat. Only a massive heat sink could dissipate such heat, so a fan is generally used to assist cooling.
You could always mount it somewhere out of the way and use an extension lead, being careful to avoid damp and maintain a fresh air supply.
Prices are falling dramatically. Aldi do 150W ones for £14.99. I paid £50 4 years ago.
Never heard of a powerful silent one. My 150W one, that I never use coz its rubbish is silent, but the powerful ones generate heat. Only a massive heat sink could dissipate such heat, so a fan is generally used to assist cooling.
You could always mount it somewhere out of the way and use an extension lead, being careful to avoid damp and maintain a fresh air supply.
Prices are falling dramatically. Aldi do 150W ones for £14.99. I paid £50 4 years ago.
-
pippin
Herr Ohm started it all, but it is well worth harking back to some basic theory.
V=I/R W=V2/R W=VxI and various other equations all come into play.
Don't worry what they mean, just be aware of the results of using them.
Say you have a 1000Watts kettle, which is what many travel ones are, and anyway round figures make things easier.
At mains voltage (say 250Volts) that kettle will draw some 4Amps.
What does that mean? Well, the ring main is capable of handing 32A and your house electric main fuse will be at least 100A strong so you are not going to blow it.
Not only that but one unit of electricity is one kilowatt used for one hour.
At about 10p per unit that is what it costs to boil a kettle for an hour.
Which is all pretty insignificant in the scheme of things - unless you are a real "greenie"!
OK, so now you want to boil that same kettle in the Bongo via an inverter from your 12V battery.
An inverter is a fancy but short name for a gubbins that will convert your 12V DC battery up to 240V AC mains.
1000W (or 1kW) is still what is required to raise the temperature of 1kg of water by 1C in 1 second (I think!).
Electrical laws from those equations now mean that at 12V the current drawn from the battery will be 1000 divided by 12 which is a massive 80A, yes eighty amps!
For other reasons that requires seriously thick wire and a meaty fuse.
Now, what about the battery? Well a hefty battery is around 100Ah.
100 ampere-hours.
Theoretically it will provide 1 amp for 100 hours or 100 amps for 1 hour, or any combination inbetween.
Theroretically, in practice less than half that before the voltage drops too far, so 50Ah it is.
Remember - 80A is what your little kettle draws at 12V
You try to boil that kettle for 1 hour and your battery will be flat. Very flat. Not only that but the tea will not taste very good either!
Moral of the story - apart from having bored the pants off you?
Do not even think of using an inverter unless you really have to and then only for something that has no possibility of being run from 12V.
And certainly not for anything that gives out any amount of heat.
You can buy dedicated lap-top chargers that run directly off 12V - far more efficient than using your mains charger via an inverter.
TV's & DVD's that are designed for 12V (they come with adaptors for 240V!)
Any 240V conventional microwave oven will take about twice the power that it puts out (750W? that's 1,500W).
Inverter? No chance!
There are 240V AC electronic power supply ones that are more efficient but they are unlikely to take kindly to use on an inverter - BANG!
So, buy a dedicated 12V one. Bloody expensive but will be far more efficient. Despite still taking 1000W, with a couple of leisure batteries you have a chance.
E&OE
V=I/R W=V2/R W=VxI and various other equations all come into play.
Don't worry what they mean, just be aware of the results of using them.
Say you have a 1000Watts kettle, which is what many travel ones are, and anyway round figures make things easier.
At mains voltage (say 250Volts) that kettle will draw some 4Amps.
What does that mean? Well, the ring main is capable of handing 32A and your house electric main fuse will be at least 100A strong so you are not going to blow it.
Not only that but one unit of electricity is one kilowatt used for one hour.
At about 10p per unit that is what it costs to boil a kettle for an hour.
Which is all pretty insignificant in the scheme of things - unless you are a real "greenie"!
OK, so now you want to boil that same kettle in the Bongo via an inverter from your 12V battery.
An inverter is a fancy but short name for a gubbins that will convert your 12V DC battery up to 240V AC mains.
1000W (or 1kW) is still what is required to raise the temperature of 1kg of water by 1C in 1 second (I think!).
Electrical laws from those equations now mean that at 12V the current drawn from the battery will be 1000 divided by 12 which is a massive 80A, yes eighty amps!
For other reasons that requires seriously thick wire and a meaty fuse.
Now, what about the battery? Well a hefty battery is around 100Ah.
100 ampere-hours.
Theoretically it will provide 1 amp for 100 hours or 100 amps for 1 hour, or any combination inbetween.
Theroretically, in practice less than half that before the voltage drops too far, so 50Ah it is.
Remember - 80A is what your little kettle draws at 12V
You try to boil that kettle for 1 hour and your battery will be flat. Very flat. Not only that but the tea will not taste very good either!
Moral of the story - apart from having bored the pants off you?
Do not even think of using an inverter unless you really have to and then only for something that has no possibility of being run from 12V.
And certainly not for anything that gives out any amount of heat.
You can buy dedicated lap-top chargers that run directly off 12V - far more efficient than using your mains charger via an inverter.
TV's & DVD's that are designed for 12V (they come with adaptors for 240V!)
Any 240V conventional microwave oven will take about twice the power that it puts out (750W? that's 1,500W).
Inverter? No chance!
There are 240V AC electronic power supply ones that are more efficient but they are unlikely to take kindly to use on an inverter - BANG!
So, buy a dedicated 12V one. Bloody expensive but will be far more efficient. Despite still taking 1000W, with a couple of leisure batteries you have a chance.
E&OE
-
swifty
-
mikeonb4c
- Supreme Being
- Posts: 22877
- Joined: Sun Nov 05, 2006 10:49 pm
- Location: Living with Mango Bongo in the North West but with a tendency to roam
- Contact:
Well I got a 400W inverter (Clarks) off ebay for £30 delivered and v happy with it. I run a 4-gang lead off it (and this is neatly velcro'd to the centre console. On the move, it is simply a means of using household devices like phone chargers, PS2, portable DVD/TV, laptop etc. etc. just as though you were at home and without having to get all those extra in car charger / power supply things. I love that. But once camped up, I wouldnt expect it to do anything v useful for long (although just being able to recharge phones etc is still handy). I'm wondering if it will run a low wattage hairdryer when engine is running too as this could be mega when getting young ladies out of the house (you can dry it while we are driving dear!!)
Mike
Mike
-
mikeonb4c
- Supreme Being
- Posts: 22877
- Joined: Sun Nov 05, 2006 10:49 pm
- Location: Living with Mango Bongo in the North West but with a tendency to roam
- Contact:
Dandy - something I meant to ask. I mounted mine behind the glove compartment as per your suggestion. I used Gorilla tape but it still creeps round and end s up fouling the glove box door. How have you fixed yours so that it stays in position, when the mounting base is a smooth round pole.
Now dont get rude everyone please
Now dont get rude everyone please
-
Lovejoy
Thanks Pippin, for a truly novel experience. A physics lesson I understood. Well most of it anyway 
What you are basically saying is that all that time spent mounting and wiring up my inverter was, erm, a complete waste of time.
Except it does run my laptop. So I saved the cost of a 12v laptop power supply. But probably spent twice as much on the inverter and socket.
The other thing it does run quite nicely, is my DAB digital radio. I ave not found one of those yet which runs off a 12v supply (Ok, the very next post will be a link of where to find one, or an adaptor), and anyway I have 2 of them now so would not want to go and spend a lot of money on one just for the Bongo. So I can enjoy my Pure Evoke-1 in the Bongo.
Oh, and i'm hoping it will run my electric shaver for which I have a 3 pin adaptor, but I haven't tried that yet as i've never been away more than a day
What you are basically saying is that all that time spent mounting and wiring up my inverter was, erm, a complete waste of time.
Except it does run my laptop. So I saved the cost of a 12v laptop power supply. But probably spent twice as much on the inverter and socket.
The other thing it does run quite nicely, is my DAB digital radio. I ave not found one of those yet which runs off a 12v supply (Ok, the very next post will be a link of where to find one, or an adaptor), and anyway I have 2 of them now so would not want to go and spend a lot of money on one just for the Bongo. So I can enjoy my Pure Evoke-1 in the Bongo.
Oh, and i'm hoping it will run my electric shaver for which I have a 3 pin adaptor, but I haven't tried that yet as i've never been away more than a day
-
dandywarhol
- Supreme Being
- Posts: 5446
- Joined: Mon Dec 19, 2005 10:18 pm
- Location: Edinburgh
The back of my 700W microwave states that it's power consumption is 1200W and my 1200W invertor (2000w surge) just copes with it to heat a precooked meal (5 mins). I can't run the engine as I use the microwave because it would just pop the fuse from the relay (although the Towsure intelligent relay coped when I ran an ammeter in place of the fuse to see what current was being drawn - it went to the end of the 60A scale as Pippin suggests!)
To be honest, I don't think it's a good idea to draw so much from a leisure battery so quickly, so I've cut down on the microwave use but it's a really handy piece of kit to power electric drills and small grinders on occasion.
To be honest, I don't think it's a good idea to draw so much from a leisure battery so quickly, so I've cut down on the microwave use but it's a really handy piece of kit to power electric drills and small grinders on occasion.
Whale oil beef hooked
Renault Lunar Telstar
Yamaha TD1C 250, Merc SLK200, KTM Duke 690
Renault Lunar Telstar
Yamaha TD1C 250, Merc SLK200, KTM Duke 690
-
ICB
I don't know if there's a dedicated 12V external one as most people will hook a DAB unit and aerial up to their headunit, tucking the unit away somewhere in the centre console and controlling it from the HU.Lovejoy wrote:The other thing it does run quite nicely, is my DAB digital radio. I ave not found one of those yet which runs off a 12v supply (Ok, the very next post will be a link of where to find one, or an adaptor)