Invertor Efficiency

[Thomas-the-Terrano2]

Wondering how well a modern invertor convers 12V dc to 230 V ac

have several domestic items in caravan that are low wattage on
their mains only supply, ie 16" lcd tv 50W (max)

have a 150W invertor and on a good charge in the leisure battery
it works fine. Suspect battery needs to be around 12.7V to push
this, perhaps invertors need a higher Voltage ie from an alternator
for much more, or multiple charged batteries.

How do I determine the current drain on the battery.

I'm thinking if 230/12 ~ 20 then use this do multiply up the mains
Amperage.

Or just divide 50W/12V = 4A or so. Is this reasonable rule of thumb
allowing that there is an ac to dc, well dc to ac conversion in there
too.

 

[dan]

You are going to love this!

Don't buy a camping tv - pick up £100 supermarket LCD. They run 12 volts anyway, and would in threory run straight on the mains.

BUT! They are susceptible to spikes - therefore, replace the 240 supply lead and power box with an Amperor Voltage Regulator. This will come with a cigarette lighter end - but just put a 12v plug on it, or hard wire with in-line fuse.

The TV/Laptop will now run on this fine, 12v no hook up, no damage!

Inverters are only good for a short time, as they take alot from the battery.

 

[(RIP) PLANK]

to work out the drain, just put everything on and put an ammeter between the positive terminal and the battery clamp. If we are on a site together i will bring a meter :thumb2

On ebay you can get a 12v laptop charger that comes with multiple connectors and voltage selection for a £5, they claim to be regulated I was thinking of this for running a LCD TV, worth a go they are only a £5!

I will try and find the link later :thumb2

 

[Fez_uk]

most multimeter don't measure over 10a, so aslong as it's not too big thats a good way.

Have a look on google, I remember reading about them ages ago and I recall they are about 10-20% less efficient. But worth looking online to make sure.

 

[rustic]

On ebay you can get a 12v laptop charger that comes with multiple connectors and voltage selection for a £5, they claim to be regulated I was thinking of this for running a LCD TV, worth a go they are only a £5!

I have used a lap top charger on the boat, however they don't like a supply voltage of less than 12 volts, so if the battery is low, or current drain is high, or there is a large voltage drop on the wiring, then the chargers overheat, or start to switch off.

I now use a socket that has heavy duty wiring (20Amp) and it seems ok now.

Inverters are approx 90+% efficient some power lost in heat etc.
Be aware that the inverter will consume power when switched on and not supplying a load, so it's important to switch them off when not in use.

We have a 800 watt inverter on the boat, but due to lossses it wouldn't be efficient to charge a mobile phone via the 240 volt adaptor, we use a car adaptor.
The sat uses 12 volts and we have a 13" freeview tv/ dvd with usb record, and SD playback, it uses 12 volts so I made up an appropriate lead and the tv only takes 1.4 amps. TV cost under £90 from currys or whoever shares their shop now with PC World. Bought it last October and got a further £10 off on line at the time. :thumbs

 

[(RIP) PLANK]

most multimeter don't measure over 10a, so aslong as it's not too big thats a good way.

Have a look on google, I remember reading about them ages ago and I recall they are about 10-20% less efficient. But worth looking online to make sure.

I'm not bragging - much - but mine mneasures up to 200 amps :augie

and it turns out i was wrong about the laptop charger, they don't supply 12v output, only 15v upwards!

 

[Thomas-the-Terrano2]

that was my thouoght as most of this small wattage stuff is dc in side with a
transformer. some are external.

good idea about try ammeter at battery terminal, had thought of fun trying
to intecept it near item, dismantling 12v connector etc.

tbh had googled it but much was techno waffle, hoped for some real world
experience from nissanland!

Dan, good for raising that. wonder if like a pals tv it was 12v wel dual but in van
got picture but no sound. we ran the mains lead it had thru my invertor
on same van battery, hey presto sound as well. still not sure what invertor did
as we went 12 to 230 to 12 but guess boosted somehow.

gather invertors are best when close to capacity, so how do i sort my
argos alba 16 with mains only connvection?

 

[rustic]

I'm not bragging - much - but mine mneasures up to 200 amps :augie

But some clamp meters only measure ac currents and not DC currents.:nenau

So as with everything... You need to know if you are AC or DC...:naughty

 

[dan]

I will try to make it a little simple without going into sine waves etc.

When you were trying your friends TV from a 12v source, it would power up, but not have a stable power supply - so would not work 100%. Sometimes, you will get pic and no sound, other times the other way round. The 12v supply is not stable enough to supply both, as the power will rise and fall, as batteries do.

By using the invertor, you in effect stabilised the power supply, although 12v went in and came out - what it did was stabilise the outward supply so the TV could run on a nice 12dc power source. Though it did the same thing, it is not an efficient way of doing it - without getting too technical, it draws more power from the battery in order to operate.

The Amperor device is a voltage stabiliser, which does just that, takes an unstable current, stabilises it and feeds the item. 12v in 12v out, draws no more current than it needs.

 

[Thomas-the-Terrano2]

like it, googled, saw amazons ad and reviews.

ok for kit with external transformer and note
is a dropper to so can take 24v down to 12v
at same time.

my tv has mains only so no use?

will mention to pal thouhg think has since
got an invertor, has a solar panel too and
various scooter batteries on charge at anyone
time. reckon charges his lappy too.

 

[dan]

like it, googled, saw amazons ad and reviews.

ok for kit with external transformer and note
is a dropper to so can take 24v down to 12v
at same time.

my tv has mains only so no use?

will mention to pal thouhg think has since
got an invertor, has a solar panel too and
various scooter batteries on charge at anyone
time. reckon charges his lappy too.

If you tv is an LCD, and below 19" it SHOULD be 12v - have a check on the back! Your mains will come with a transformer box half way down it?

The amperor will plug into the back of the TV, where your current power lead plugs in through the jack plug. (same as lap top )

Here is the best place to get them, currently out of stock, mind, but they are popular and it is that time of year!