Further to ThreadID: 108843 115ltr fridge running on inverter

Submitted: Tuesday, Jul 29, 2014 at 21:33
ThreadID: 108940 Views:1305 Replies:4 FollowUps:1
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OKAY>>>>
Now that I know my fridge I already had is allegedly 808 watts( checked over 24 hr period....manufacturer's claim) I calculate 240v current at roughly 3.6a.......if I am right in assuming a 30% load from an inverter that would make the current drain on my deep cycle battery 4.68a .
Correct me if I am wrong if you would please, but a 1000/2000 watt inverter would handle this??? The wattage was obtained from manufacturer's paperwork. Also states on fridge power label that it would use 295kw over 12 mths. which equals 808 w(approx) per day. Hoping that someone can help me decipher this.......................PLEASE
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Reply By: John and Regina M - Tuesday, Jul 29, 2014 at 22:59

Tuesday, Jul 29, 2014 at 22:59
To convert 12v to 240v multiply by 20.
So if you need 1 amp (or 240 watt) at 240V then it takes approx 20 amps at 12v

Give or take....
So if yr fridge draws 3.6 amp at 240v then it will draw 20 x 3.6 amp inverted from 12v. Approx 72 amps.

Yes a 1k inverter will accommodate yr fridge. Just.

Add a wee bit for inefficiency.
AnswerID: 536827

Reply By: oldtrack123 - Tuesday, Jul 29, 2014 at 23:52

Tuesday, Jul 29, 2014 at 23:52
HI
It is not a simple calculation based purely on Ohms laws

You need to know the power factor that the fridge motor operates at to determine the actual amperage draw from the inverter.
That could be around 0.5>0.6 PF
At 0.5 Pf the current draw from the inverter would be around 7.2Amps

The Inverter, if it is rated 1KWatts continious [ not peak or surge]will only be able to supply 4.1A continious without over heating


PeterQ
AnswerID: 536830

Follow Up By: oldtrack123 - Wednesday, Jul 30, 2014 at 00:10

Wednesday, Jul 30, 2014 at 00:10
HI
I cannot edit so should add to the above
I very much doubt that the fridge rating is 800W
I suspect that is the average daily use& is referred to as 800Watt hrs
IF that is the case ,I would expect it to be more like 150<200W
[Check the fridge name plate ]
Your inverter will safely run that

PeterQ
1
FollowupID: 821045

Reply By: V8 Troopie - Wednesday, Jul 30, 2014 at 00:13

Wednesday, Jul 30, 2014 at 00:13
With fridges (Compressor types) its more the startup current than the running current that says yay or nay if the inverter will run the fridge. Startup current can be 10-20 times the running current for a brief time interval.
Look for an 'L' type inverter (L = low frequency), they have a massive ring type (toroid) transformer inside.
I run a large domestic fridge from 24V solar power via battery bank, the inverter is 1200W.
AnswerID: 536831

Reply By: ModSquad - Wednesday, Jul 30, 2014 at 00:41

Wednesday, Jul 30, 2014 at 00:41
Kevmac

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AnswerID: 536832

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