Submitted: Monday, Mar 03, 2008 at 18:21

ThreadID: 55148
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Replies:7
FollowUps:17

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can Anybody inlighten me on how many watts these draw per/hr.

(2007 model fridge / freezer)

cheers / mike wa

(2007 model fridge / freezer)

cheers / mike wa

Monday, Mar 03, 2008 at 18:27

Approximate calc is done by multiplying the Amps draw by the volts that gives watts.The resaon why it's approximate is that the voltage varies between normal battery voltage say 12.5 and when the alternator is running around 14. This changes the calc.

AnswerID:
290622

Monday, Mar 03, 2008 at 18:36

Mike, I think you want to know the power consumption. This is generally measured in amps per hour. Engel MT45F-S 40lt fridge freezer draws .5 - 2.5amps per hour (variable)32lt .5 - 2.5amps

60lt .5 - 4.2amps

Hope this helps

Nigel

AnswerID:
290626

Monday, Mar 03, 2008 at 18:50

We have the older 39l engel.It varies with ambient temperature.

I work on as low as 1 amp/hr at 0 to 15 deg.

Maybe 5amps/hr at 30 to 35 deg.

Also depends on how many warm beers you put in the afternoon, and if you are running it on freezer. Both pull more power.

AnswerID:
290629

Monday, Mar 03, 2008 at 19:15

The newer Engels run a more efficient compressor. My current F series 40 litre draws 2.8 amps when cycling, compared to 6.0amps by my B-series 39 litre.
FollowupID:
556001

Monday, Mar 03, 2008 at 20:02

hi old plodder , i noticed on your profile page a photo of you camping out with camper trailer , what brand was it and how did you find traveling arround with it ?do you still use it ?

reason being i am looking at buying a kimberly kamper and doing a bit of traveling arround .

regards mike / wa

FollowupID:
556021

Tuesday, Mar 04, 2008 at 09:10

Off topic to MJR.Apologies for hijacking the thread.

Are you a member MJR, did look at sending you a members message.

Yes, we have the CT for 12 months now.

Only done a few trips.

For the last 20 years we have been travelling with pajeros and a roof rack, and a 9x9 tent. Now retirement is in sight (10 years to go.), the wife decided that a little more comfort would be useful. So the idea is that all the stuff on the roof rack now goes to the trailer. I am looking forward to being able to carry more water and a little more fuel.

It is a reasonably generic soft floor 7'x'4' CT, Customline from near here in Brisbane.

Paid $6,000 2nd hand. It is not maybe as heavy duty or as well fitted out as a Kimberley Kamper. But then we are used to a more basic style of camping. And we don't get enough travelling in to see $20,000.00 plus sat in the front yard doing nothing. :o)

Am impressed by the Kimberley Kampers. When we got into Windorah late one night (after 8pm) coming in from Birdsville, a couple in a KK offered us dinner, and we had a good night chatting, and a good look through it. We were late because we had spent three hours helping out some one with three flats and two spares, so it showed us God does help those who help others :o)

So the customline CT is a new toy, and as the wife says, something else for me to fiddle on and alter. Only done three trips, nothing too serious yet, but happy with it.

FollowupID:
556110

Tuesday, Mar 04, 2008 at 23:51

Thanks for your reply john .no i am only a visitor , i only found this site 2 weeks ago and think its great how everyone helps / answers peoples problems .

i will try to become a member in the near future .

we have our caravan & camping show on next week so i carnt wait to check the of camper trailers there and compair them .

you can come away with some great ideas from shows like that .

just got to keep the Mrs away from the workshop so she carnt see what i buy !!

regards mike / wa

FollowupID:
556261

Monday, Mar 03, 2008 at 20:33

Electrical discussions can eaily be confusing, but using confusing descriptions makes it impossible to understand what's meant.Watts per hour or amps per hour is meaningless.

Instantaneous current is amps (just like instantaneous fuel flow is litres per hour).

Total current used is amphours (just like total fuel used is litres)

Where instantaneous current varies, like a cycling fridge, you could use average current, which would be the same as the amphours used in one hour.

AnswerID:
290656

Monday, Mar 03, 2008 at 20:43

Mike, As mentioned below you probably are looking for amp/hours rather than watts unless you are looking to run off a genny. You have also touched on the other question- fridge or freezer?I think that is fair to say that as a fridge it will use approx 25 amp hours (over a 24 hour period) and approx double as a freezer. But it does depend on the outside temperature, and does it have a transit bag and is it full.

With this additional info others may differ.

Regards

Mark

AnswerID:
290658

Monday, Mar 03, 2008 at 22:02

HI MowingWith all Engel fridges. the maximum power consumption is always shown on the front of all fridges. It does not matter if the fridge is in the freeze cycle or the fridge cycle, the currant draw on the MT 45FT is 2.5amps.

That's the good things about the Engel's, they do not use much power compared to other fridges on the market/

Cheers

Stephen

Roxby Downs Special Lifetime Member |

FollowupID:
556058

Monday, Mar 03, 2008 at 22:24

thanks , thats good to know , as thats the model i have mt45 anniversary pack they had on offer over at xmas , came with the new little thermo 8 and a heap of bits & peices for $1190.00 including the cover / bag .must say i am realy pleased with the way it preformed over our

xmas trip down south of wa .

FollowupID:
556063

Monday, Mar 03, 2008 at 23:31

Hi Stephen, This is a bit of a misconception....... as you see the true power draw of a fridge is over a 24 hour period. Just to give an example, the Engel may only draw 2.5amps but if it does that for 24 hours it will use 60amp hours. If a fridge uses 4.5 amp hours but does it for 10 hours it will use 45 amp hours. Which one are you better off with?A classic example is the Trailblaza which draws about 4.5amp hours and as a result you need a good size power lead and the battery to be holding a good charge. The compressor is running at high speed and their results are that you need to get things cold (ie get the heat out quickly to be the most efficient.) Don't fall for the per hour amp draw as it is snake oil stuff. What you need to know is what the fridge will take out of your battery over a 24 hour period so that you know what size battery you need or how much charge you need to put back in. The Autofridge is far more economical than the Engel but uses more power on a hourly basis. Hope this helps Regards Mark

AnswerID:
290693

Tuesday, Mar 04, 2008 at 08:54

Thanks for clarifying that mowing.In my earlier response I was working on an average over a number of hours, then dividing by the number of hours, to get an amperage per hour which could be misleading.

I find I get a higher current draw during the day, and lower at night, obviously due to ambient temperature. If we are travelling during the day, and the battery is being charged, it not such an issue, but if stationary, it needs to be allowed for.

Yours is a better response.

FollowupID:
556103

Tuesday, Mar 04, 2008 at 11:31

Remember, the fridge is really only drawing current when the compressor is working. With our 39L Engel, the compressor works for only say 5 min every hour when there is not much in it on a cold day but can run continuously on a 40+ degree day when you are opening it all the time..This means that there can be a huge difference in power consumption over say a 24 hr period depending on the ambient temperature, what is in the fridge, how cold it is, how often is it opened, what setting you have on the fridge, age of the fridge, etc.

The power comsuption could be as low as 5 watts per hour and as much as 50 to 70 watts per hour.

Stevesub

AnswerID:
290726

Tuesday, Mar 04, 2008 at 13:02

"The power comsuption could be as low as 5 watts per hour and as much as 50 to 70 watts per hour."- do you mean "as low as 5 watts average".

- "watts per hour" is meaningless, watts is an instantaneous measure. It's like saying my generators fuel consumption is 5 litres.

FollowupID:
556138

Tuesday, Mar 04, 2008 at 13:44

The power companies use a measure Kilowatt or megawatt hour to measure how much power people are using. The terms mean how many watts , 1000's of watts or millions of watts of electricity are being used over 1 hour.The measurement of a watt of electricity is current (amps) x voltage ie 1 amp at 12v is 12 watts.If you are pulling 1 amp from a 12v battery for 1 hour this is 1 watt per hour. 2 amps for 30 mins from 12 volts and 0 amps for 30 mins is that same 12 watts per hour.

For a fridge, there are several important factors - voltage which we assume is 12V for a car battery (could be up to 14V). Then how much current can the battery deliver (100's of amps for a car battery, 1 amp if you are lucky from a torch battery - both for a very short time) and also what capacity is the battery 60 to 100 Amp hrs for typical automotive batteries. If the battery is 60AH, it can deliver 60 amps for 1 hour (Maybe in practice if you are lucky) or 1 amp for 60 hours (which is more likely).

The 60amps in 1 hour is actually 720 watts at 12V ie if 60 ampos were drawn for 1 hour, that would be 720 watts per hour. 1 amp for 60 hours at 12 V is 12 watts per hour.

Get where I am coming from. I said Watts PER hour (or to simplify it for some) - average watts per hour, same thing)

I have spent over 40 years in the electrical industry so I should know a bit about basic current, volts and watts and the terminology that is used.

My 39l Engel will run for days on a 12V car battery is the ambient temp is low, etc as it uses on average 5 to 10 watts per hour. The instantaneous power usage is about 48W (4 Amps) when the compressor is running but it only runs 5 to 10 m ins every hour. From a 60AH battery, the Engel will run for 60 hrs

However if I use my smaller different technology solid state Waeco fridge I am using 48 watts per hour (4 amps all the time) so my battery will last 1/4 the time. From a 60AH battery, the Waeco will run for 15 hrs

However in the worst case with the Engel in 40+ temps and opening all the time, it will use the same watts per hour as the Waeco and the battery will only last 15 hrs.

Off-topic - the solid state Waeco is next to useless in QLD for 6 months of the year as it only cools to 20 degrees below ambient which is not cold enough to keep the beers real cold. No such problems with the Engel

Stevesub

FollowupID:
556142

Tuesday, Mar 04, 2008 at 14:00

"If you are pulling 1 amp from a 12v battery for 1 hour this is 1 watt per hour. "- no, 1 amp for 1 hour is 1 amphour (amps multiplied by hours).

- 1 watt for 1 hour is 1 watthour (watts multiplied by hours)

- watts PER hour implies watts DIVIDED by hour.

Look at the International Electrotechnical Commission standard units if you like - watthours appears in their list, watts per hour certainly doesn't.

I've also worked in Electrical Engineering for forty years - still hasn't made me infallible.

FollowupID:
556144

Tuesday, Mar 04, 2008 at 14:27

The original post asked for watts per hour which is what I have attempted to give the poor now confused soul.Watts per hour is a longer version of watthours - same thing although technically watthours is correct if you really want to be my English teacher.

Watts is current x voltage so 1 Amp at 12V is 12 watts. (typo in my previous post) Pull 1 amp out of a 12 v battery for 1 hour, you have 12 watthours or 12 watts per hour.

I am out of here for rest the day now as I have better things to do with my time today than argue the toss about watthours and watts per hour..

Stevesub.

FollowupID:
556154

Tuesday, Mar 04, 2008 at 14:51

"Watts per hour is a longer version of watthours - same thing although technically watthours is correct if you really want to be my English teacher.""Pull 1 amp out of a 12 v battery for 1 hour, you have 12 watthours or 12 watts per hour."

If you can't understand that there is a fundamental difference between

- watts TIMES hours (watthours) and

- watts DIVIDED BY hours (watt per hour)

then we're both wasting our time here.

FollowupID:
556167

Thursday, Mar 06, 2008 at 22:08

Hi Stevesub, Your reply made sense, and probably assisted with the original question.What cant work out is the final couple of followups to your reply.

We are talking about the amount of current used per hour.

I prefer to talk in Amps, some talk in watts. Watts is easily converted to differing voltages, Amps is too, just one more calculation.

As we are all interested in amount of power used by our appliances every hour so we can work out our battery sizing, then by Mikes reckoning,

- watts TIMES hours (watthours) and

- watts DIVIDED BY hours (watt per hour)

in the context of the discussion, both are the same. If you multiply by 1 or divide by 1 you end up with the same result.

I dont however agree with the watt per hour being a division though, Words per minute is a good example. By the same reckoning, if you type longer you type less??? No matter which way you look at it, if you draw 1 watt per hour you are drawing 1 watt multipied by how many hours you draw this for.

Also, I am confused WRT the last follow up, The follow up states ""Watts per hour is a longer version of watthours- same thing although technically watthours is correct" then -

"If you can't understand that there is a fundamental difference between watts TIMES hours (watthours) and

- watts DIVIDED BY hours (watt per hour)"

First line says they are the same, finishing off with they are different

I'm with you Steve

Ray

FollowupID:
556648

Thursday, Mar 06, 2008 at 23:23

Oops sorry, first line was Steves, Rest was Mikes. Per is still the same as every though, sorry for the confusion.Ray

FollowupID:
556672