electrical conversion calculation

[capnthommo]

hi everybody

i wonder if the leccy whizzes on the forum can confirm my calculations please.

i am intending to get a 220 volt fridge and the energy consumption is rated at 150 kWh per year

the figures i get from calculating this to amp/hours are as follows

 

energy consumption 150 kilo watt hours per year = 150000 watt hours at 220 volts

watt hours per day 410.9589

voltage 12

average amp hours 1.4269

total amp hours per day 34.2466

 

i realise i will have to add a percentage (20?) to account for power losses through the inverter but do my figures look about right? ie will the fridge account for about 35 ish amp hours of my precious batteries every day?

 

thanks in advance - this one has been bugging me beyond belief.

cheers

nigel

 

Edit to correct the appliance voltage

Edited May 28, 2010 by capnthommo

[paulcatchpole]

hi everybody

i wonder if the leccy whizzes on the forum can confirm my calculations please.

i am intending to get a 220 volt fridge and the energy consumption is rated at 150 kWh per year

the figures i get from calculating this to amp/hours are as follows

 

energy consumption 150 kilo watt hours per year = 150000 watt hours at 120 volts

watt hours per day 410.9589

voltage 12

average amp hours 1.4269

total amp hours per day 34.2466

 

i realise i will have to add a percentage (20?) to account for power losses through the inverter but do my figures look about right? ie will the fridge account for about 35 ish amp hours of my precious batteries every day?

 

thanks in advance - this one has been bugging me beyond belief.

cheers

nigel

 

The numbers add up, but don't underestimate the inverter losses, work at dividing by 10, to give 41.1ah/day.

 

It also seems quite an efficient fridge?

 

Our 230v fridge, B-rated, admittedly, uses more like 65ah/day.

 

PC

[PaulD]

Your calculation is correct (apart from the 120v which is not part of the calculation).

 

Most fridges would consume more than that - more like 48 amp hours per day. There are several threads comparing 12v and 240v fridges.

 

Paul

[capnthommo]

The numbers add up, but don't underestimate the inverter losses, work at dividing by 10, to give 41.1ah/day.

 

It also seems quite an efficient fridge?

 

Our 230v fridge, B-rated, admittedly, uses more like 65ah/day.

 

PC

 

hi paul and thanks

yes, it does seem pretty efficient. but it's only 5.8 cu/ft and is also A rated and has no freezer compartment.

anyway, yes 40 ish amp/H a day is quite doable. can finally put this one away then and find something else to fret about.

cheers again

nigel

 

Your calculation is correct (apart from the 120v which is not part of the calculation).

 

Most fridges would consume more than that - more like 48 amp hours per day. There are several threads comparing 12v and 240v fridges.

 

Paul

 

cheers - yes the 120v is a mistook. should have read 220 - domestic mains voltage. and 50 amp/h shouldn't present any problem either

cheers

nigel

[twocvbloke]

Just to be PITA, 220v is the European standard voltage (EU says it's 230v, but the tolerances allow the 20v difference between ours and theirs), proper British electrickery is 240v, so could muck up the calculations...

[Gibbo]

Just to be PITA, 220v is the European standard voltage (EU says it's 230v, but the tolerances allow the 20v difference between ours and theirs), proper British electrickery is 240v, so could muck up the calculations...

 

Until the EU redefine the volt so we can have a nice round number like 100.

 

I wouldn't put it past them.

[WotEver]

Until the EU redefine the volt so we can have a nice round number like 100.

 

I wouldn't put it past them.

Then we could have a new plug that looks like 100 - the earth pin and the two phase pins... | O O

 

T

[Justme]

Just to be PITA, 220v is the European standard voltage (EU says it's 230v, but the tolerances allow the 20v difference between ours and theirs), proper British electrickery is 240v, so could muck up the calculations...

 

If he has a good inverter he can set the V to whatever he wants. The fridge will still use the same amount of power any way just the (mains) amps will change the watts will stay the same. Lower the V & up the A cos the W is fixed.

 

 

 

Inverter consumption might change.

[Grace and Favour]

hi everybody

i wonder if the leccy whizzes on the forum can confirm my calculations please.

i am intending to get a 220 volt fridge and the energy consumption is rated at 150 kWh per year

the figures i get from calculating this to amp/hours are as follows

 

energy consumption 150 kilo watt hours per year = 150000 watt hours at 220 volts

watt hours per day 410.9589

voltage 12

average amp hours 1.4269

total amp hours per day 34.2466

 

i realise i will have to add a percentage (20?) to account for power losses through the inverter but do my figures look about right? ie will the fridge account for about 35 ish amp hours of my precious batteries every day?

 

thanks in advance - this one has been bugging me beyond belief.

cheers

nigel

 

Edit to correct the appliance voltage

Hmm - - Nigel - - May I ask - - what's the wattage of the unit please? (rather than the KWh per Year)

[capnthommo]

Hmm - - Nigel - - May I ask - - what's the wattage of the unit please? (rather than the KWh per Year)

 

hi there

im afraid i am not sure but as well as i can recall the watts specified is about 70 or 80. the info sheet only gives a kW/H per year which i assume is the consumption averaged over 365 days. i am basically trying to get a reasonable estimate of the daily usage in amp/hours so i can relate that to the amount it is going to suck from the 440 amp/h battery bank via the inverter.

i tried to work it out with a pencil but ended up going to an online conversion app that gave me the figure i mentioned in the originl post.

i can cope with maybe 60 or so amp/h per day but certainly wouldnt want to sacrifice more than say 80 ish.

we will be using whatever we can on 12volt but some things will need to be 240 via inverter (tv, fridge mostly) just don't want to buy something that will be too hungry in terms of leccy.

cheers

nigel

[twocvbloke]

Until the EU redefine the volt so we can have a nice round number like 100.

 

I wouldn't put it past them.

 

Nah, there's always rumours that the EU wants us to convert our electrickery systems to the European standards, like using Europlugs, using 230v, using Edison Screw lightbulbs etc...

 

It ain't happening, there'd be too much money for them to lose if they made us do it, money rules everything...

[capnthommo]

Nah, there's always rumours that the EU wants us to convert our electrickery systems to the European standards, like using Europlugs, using 230v, using Edison Screw lightbulbs etc...

 

It ain't happening, there'd be too much money for them to lose if they made us do it, money rules everything...

not so sure about that; i would cite the diesel derogation in evidence. that came from europe didn't it?

the learning curve for me with regard to the lectrics has been beyond the vertical so i always like to check anything i aint sure about (practically everything)

cheers

nigel

[capnthommo]

okay folks

i think i'm sorted now. so thanks for the help.

don't think there will be any problem.

cheers all

nigel