How much will a 300 watt inverter use

Trish1997

Guest
What uses up the juice in the battery most.. a 300 watt inverter to run a 48 watt humax free sat box please?
Anyone know?
I can't find a 12 volt free sat recorder with 2 tuners.
I can find a free sat receiver that will record from USB but I want one with an inbuilt hard disc.
We are off ehu for a while next week and don't want to delete the battery leaving us 20th no power for other important stuff like pumps etc.
We already have a 300watt inverter but would buy another smaller wattage one if it saved more battery juice.
We have 2x110amp batteries and only a 60 watt suitcase solar panel.
I want to go more off grid in the future and not rely on ehu and I would be grateful for any advice please?
 
I'm fairly certain the Humax box is 12v, it has a mains transformer which supplies 12v to a socket at rear of box.
It may be that you would need a stabilized 12v supply thou.
 
What uses up the juice in the battery most.. a 300 watt inverter to run a 48 watt humax free sat box please?
Anyone know?
I can't find a 12 volt free sat recorder with 2 tuners.
I can find a free sat receiver that will record from USB but I want one with an inbuilt hard disc.
We are off ehu for a while next week and don't want to delete the battery leaving us 20th no power for other important stuff like pumps etc.
We already have a 300watt inverter but would buy another smaller wattage one if it saved more battery juice.
We have 2x110amp batteries and only a 60 watt suitcase solar panel.
I want to go more off grid in the future and not rely on ehu and I would be grateful for any advice please?


The Humax HDR-1100s is a dual input HD freesat box. Mine has a 1TB hard drive in it. The input voltage is 12v at 4A (48 watts).

Your box will be the same power (48 watts) but with some loss because of the inverter.
 
A smaller inverter will not make much odds as you will still be taking 48+ watts. The quiescent current difference between a 300 watt and say 150 watt will be very small.
 
. a 300 watt inverter to run a 48 watt humax free sat box please?

The Inverter needs to produce 48 watt at 240v, but they are only 80-90% efficient so it will need to take in 53-60 watt at 12v which is 4.5 to 5 amp.

So, in perfect conditions, ever hour of brilliant Mediteranian sunshine will power your free sat box for a hour in perfect conditions, but of course you are also using TV & lights etc.
My guess is that in Autumn in UK you'll be OK for 2-3 days (Turn box off when not in use) before the battery voltage drops too far.

Best thing is to test it at home or on a site where you can hook up when the batteries aren't up to it.
I did this on my previous MoHo and (UK in November) after four nights the TV failed because of the battery voltage drop.
I'd told the site owner what I was doing and he only charged for hook up from day 5.

Good Luck
 
I'm fairly certain the Humax box is 12v, it has a mains transformer which supplies 12v to a socket at rear of box.
It may be that you would need a stabilized 12v supply thou.

Our free sat box is definitely 240v it's abut 5 years old now and I can't find one to do the same
 
The Humax HDR-1100s is a dual input HD freesat box. Mine has a 1TB hard drive in it. The input voltage is 12v at 4A (48 watts).

Your box will be the same power (48 watts) but with some loss because of the inverter.

I've just looked that one up, it doesn't mention that it will power up from 12 volt but you are saying it does?
That will make my search very easy if it will, thanks.
 
I'm fairly certain the Humax box is 12v, it has a mains transformer which supplies 12v to a socket at rear of box.
It may be that you would need a stabilized 12v supply thou.

Ours is the older one so is 240v with no transformer box on it, it has a fixed 3pin plug to the rear of the box.
It must be the never ones that do that.
Funnily I asked in curry's about it and the guy said it wouldn't work on 12 volt which is why I'm still searching but I think administration has solved our problem .. thanks admin.
 
What uses up the juice in the battery most.. a 300 watt inverter to run a 48 watt humax free sat box please?
Anyone know?
I can't find a 12 volt free sat recorder with 2 tuners.
I can find a free sat receiver that will record from USB but I want one with an inbuilt hard disc.
We are off ehu for a while next week and don't want to delete the battery leaving us 20th no power for other important stuff like pumps etc.
We already have a 300watt inverter but would buy another smaller wattage one if it saved more battery juice.
We have 2x110amp batteries and only a 60 watt suitcase solar panel.
I want to go more off grid in the future and not rely on ehu and I would be grateful for any advice please?

It's not an exact science until you choose your inverter.

Inverters do waste a lot of energy, hence the heat given off, possibly as much as double the input for the amount of output in some circumstances.

I have a cheap one kilowatt inverter and that takes a awful lot of amps to even start up before any load is applied.

:sleep-027::sleep-027::sleep-027:
 
Basic Not black & white but I would say the TV would also draw lots of power too (fast)
to last long which isn't mentioned.

Then why not also split the batteries positive (red) lead away from each other once settled
and all the driving charge is then completed (remember to connect them back together(small spark) (whilst not running engine as a huge spark when touching connection back on. So when moving away to charge the separated battery once again. But run the sat box from the separated battery and use the solar to charge that one only (keep an eye on voltage (use a meter)to no less that 11.7 volts on either)

(You can work out power using this equation: P(P is the power in watts) = I × V. , W. I is the current in amperes (amps), A. V is the potential differences in volts, V.

I
___________
V X W Watts

so to work out Amps

I(current)
=
V X W Watts

12 x 0.3
300watt inverter will (on average use) but a battery loses voltage as well as it goes along,

The simple answer is- divide the load watts by 10. E.g. For a load of 300 Watts, the current drawn from the battery would be:


300 (w)÷ 12 (v)= 25 Amps(I) (quite a large draw)

Also characteristics of a leisure battery works different to a led acid so does NiCad dry cell etc etc ...

• For a more accurate calculation of battery current: Divide load watts by actual battery voltage, this will be in the range 12-14V.

Then to allow for inverter efficiency, typically 85%, divide the figure by 0.85. Thus:

For a 300W load at 12V....300 ÷ 12 ÷ 0.85 = 29.4 Amps.
(and between fully charged)
For a 300W load at 14V....300 ÷ 14 ÷ 0.85 = 25.2 Amps.


You can see the simple divide by 10 gives an easy estimated "worst case" guide.
Notes:
• It is the actual load watts drawn, not the inverter rating that counts as the load drwn will change with the units you use. So a 1500W inverter with a 500 Watt load would be 50 Amps, not 150 Amps.The same inverter with a 1200 Watt load would draw 120 Amps.

• For a quick idea of how long a battery will last without the alternator running (but with the trickle charge of the solar not included),


How long will my battery last with an inverter load is impossible to estimate also really, no one can give you a definitive answer without all the facts

SO answer
(read a book)no sorry

The other free sat receiver shouldn't be too bad if you could use a directly connected 12 V DC free sat /recorder receiver to 12v DC which would be far superior and far less draw.

As it wont be transforming power then up 12v to 230v AC on the inverter so then back down 240AC down to 12vdc for sat boxes all drawing precious power away to transform the power.

I hope that isn't gobbledygook
 
I've just looked that one up, it doesn't mention that it will power up from 12 volt but you are saying it does?
That will make my search very easy if it will, thanks.
It come with a 240v power supply that outputs 12v at 4a. All the 12v outlets in my van are regulated at 12v, so I just cut the lead off the power supply and hooked it up.

You can add one of these in line just to make sure you don't over voltage it.

DROK® DC-DC Buck Boost Converter Voltage Regulator: Amazon.co.uk: Electronics
 
You could get a roof mounted panel 100 / 120 for not a lot of money which would save you having to move the solar panel every time the sun decides to change position. Although we don't bother with satellite tv, we do have a 300w inverter, 2 x 110 batteries + 110 solar panel and in 3 years have never run out of power
 
It come with a 240v power supply that outputs 12v at 4a. All the 12v outlets in my van are regulated at 12v, so I just cut the lead off the power supply and hooked it up.

You can add one of these in line just to make sure you don't over voltage it.

DROK® DC-DC Buck Boost Converter Voltage Regulator: Amazon.co.uk: Electronics

A bit off-topic, but when you say "...all the 12v outlets in my van are regulated at 12v", could you give some more info on the regulator kit you used?
 
You could get a roof mounted panel 100 / 120 for not a lot of money which would save you having to move the solar panel every time the sun decides to change position. Although we don't bother with satellite tv, we do have a 300w inverter, 2 x 110 batteries + 110 solar panel and in 3 years have never run out of power

I'm looking at a roof solar panel as a replacement but can't find someone to fit it yet.
The tv is also 48w but that runs from 12volt.
 
Ours is the older one so is 240v with no transformer box on it, it has a fixed 3pin plug to the rear of the box.
It must be the never ones that do that.
Funnily I asked in curry's about it and the guy said it wouldn't work on 12 volt which is why I'm still searching but I think administration has solved our problem .. thanks admin.

Ah I see, the very early ones where 12v, and I was looking at the one Admin mentioned only last week in Maplins as this question comes up every now and then, and that too was 12v, so it would seem somewhere between they where 240v.
 
Quite a high power drawer 50W in M/H battery terms.

I suppose Terrestrial Digital Freeview is a non starter then.
Some of the stand alone DVB 1Tb HDD recorders with twin tuners
run at 18/24 Watts. Less than 50W with a 22" LED TV.
 
Quite a high power drawer 50W in M/H battery terms.

I suppose Terrestrial Digital Freeview is a non starter then.
Some of the stand alone DVB 1Tb HDD recorders with twin tuners
run at 18/24 Watts. Less than 50W with a 22" LED TV.

I tried one of them and when viewing the second channel it was very pixelated so the signal.must drop on the the other channels while recording or watching another so I'd like to stick to freesat,also can't get freeview in France, well you can but nothing I can understand.
 
I'm looking at a roof solar panel as a replacement but can't find someone to fit it yet.
The tv is also 48w but that runs from 12volt.


Recently fitted one of these. 12V 150W Xplorer German Cell Solar Panel Kit - Alpha Batteries

All you need after this is a tube of Skaflex 512 or similar ana roof gland Waterproof Roof Cable Entry Gland / Box - Solar Panel Caravan Motorhome 7918101

I'm sure that someone from the forum would be willing to help you fit it.

Cheers

H
 
I've just looked that one up, it doesn't mention that it will power up from 12 volt but you are saying it does?
That will make my search very easy if it will, thanks.


OK back to basics .

Whilst most electronic devices plug into household mains sockets (e.g. 240v AC) the circuits inside require low (e.g. 12v) voltage Direct Current.

So the manufacturers have to convert the mains into low voltage.
They do this in one of two ways.
a) A separate box (somewhere between cigarette packet and house brick size) that has two wires coming out of it.
One wire goes into the mains, the other wire into the device.
The box contains electronics to change form high AC volts to low DC volts.
The box will be labeled with input and Output voltages.
b) Is basically the same but the box is inside the device.
This means that the manufacturer only needs to change the internal or external box to sell the device in different countries.

So if you have option "A" and the output is 12v you can throw the box away and use the device direct from your vans 12v.
You will need a suitable lead and preferably a regulated 12v as mentioned earlier.

IF you have option "B" the same applies.
Open the device take out and throw away the internal box and fit a 12v socket onto the wires that were previously connected to the output from the box.
Then you are in the same situation as option "A". While you are at it throw the warranty away as well.

To be blunt if this confuses you don't even think about it. Find a different solution e.g. a generator.
 

Users who viewed this discussion (Total:0)

Back
Top