running engel overnight?

Submitted: Thursday, Jun 30, 2005 at 21:47
ThreadID: 24337 Views:3606 Replies:18 FollowUps:8
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G'day,
I'm sure there will be many opinions on this: would it use more battery power to leave the engel (run as a fridge not a freezer) switched on overnight, or to switch it off, and then turn it back on again in the morning?
Would there be different results between hot weather all the time and other conditions, like hot days/cold nights such as you find in the desert?
My thinking is that it would use more power when you restart it in the morning, as it would have to pull the contents down to the preset temperature, which would use more power than holding the beer at that temperature. What does anyone else reckon?
Cheers,
Alex
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Reply By: Sand Man (SA) - Thursday, Jun 30, 2005 at 22:17

Thursday, Jun 30, 2005 at 22:17
Alex,

IMO the ambient temperature inside a vehicle at night would be fairly low and constant and therefore there would be minimal loss of cold air from the inside of the fridge. So, the fridge would cycle much less than what it would during the day.

My thoughts are that the amount of energy (current) needed to maintain a constant temperature by cycling on and off would be equal to or less than that consumed to "pull" a warmer fridge back down to the preset temperature.

Overall, leaving the fridge powered up all the time must be better for the contents by maintaining them at a constant temperature.

I have tried both ways and I seem to get about the same usable "life" from the auxiliary batteries. Now I just leave it running all the time.

Bill


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AnswerID: 118320

Reply By: GUPatrol - Thursday, Jun 30, 2005 at 22:17

Thursday, Jun 30, 2005 at 22:17
Alex,
From my experience, what makes the most difference is the number of times you open and close it and if you take something out ie: milk, leave it out for a while and then put it back in slightly warmer.
I tried all the options, warmer weather off course is harder on the fridge but if its warm and you don't open it then it is just fine for a couple of days
ie: I have left the car with running fridge and went for a two day bushwalk and the battery handled it a lot better than with us camped, getting drinks cooking etc (where we open the fridge).
With regards to the night, if its cool not much difference but on warm nights if you turn it off you run the risk of letting the temp climb too high for some foods and spoil them, then in the morning you still have to use the power to cool everything down.
Having said that, on occasions when I know I am leaving the next morning and the battery is getting low, I turn it off and wait until the next day, that way when I turn it on again it will be with the alternator charging up.

I never replace drinks as I use them... if I am leaving in the morning I reload it then, if I am staying, I leave the drinks to be loaded outside in the cool of the night and load it up first thing in the morning.
I hope it helps...
Will
AnswerID: 118321

Reply By: Member - Cocka - Thursday, Jun 30, 2005 at 23:40

Thursday, Jun 30, 2005 at 23:40
Don't know about the plus' & minus' about how much power is going to be saved by what you're suggesting, I think it's debatable until tested under control conditions.

However the biggest consideration to efficient performance is making sure heat, both generated and ambient, is removed from around the condensors. The fridge motor must have good ventilation to disperse the heat extracted from within the unit. Motors will run almost continuously if they are stewing in their own heat. Plan well the installation to achieve ventilation at all times.

Consider installing a small computer fan beside the motor to blow out trapped heat & blow fresh air across the condensors, available cheap at DS or Jaycar. This will decrease power consumption by up to 50%.

What amazes me with some fridge brands is, to reduce costs, weight & bulk they make fridges with thin walls and then suggest you buy insulating covers to improve their efficiency. Should've made it efficient in the first place. These covers also partially close over the ventilation systems around the motors & trap heat. Poor planning.
And while I'm on this band wagon, the covers they make are dark on the outside & lined with silver foil inside. Physics taught me that silver reflects and dark absorbs heat - the covers are made inside out.

If the weathers hot also consider hanging a wet towel over the carcase (evaporation cools).

AnswerID: 118338

Reply By: Member - Davoe (Widgiemooltha) - Friday, Jul 01, 2005 at 01:07

Friday, Jul 01, 2005 at 01:07
Dont forget in the morning you probably will be driving around. Generally leave ir on overnight in warm weather otherwise turn it off
AnswerID: 118343

Reply By: Bob of KAOS - Friday, Jul 01, 2005 at 07:13

Friday, Jul 01, 2005 at 07:13
I can't believe the erudition of my fellow 4WDers. Anyone reading this post could gain the impression that the members of this forum are intelligent and thoughtful. Of course that would be a completely false impression.
AnswerID: 118348

Follow Up By: Nudenut - Friday, Jul 01, 2005 at 07:37

Friday, Jul 01, 2005 at 07:37
i'm dumbfounded by the question...i have absolutely no idea if a light globe burning all night will more or less power than one which is switched off..............................................duh!
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FollowupID: 373523

Follow Up By: Member - John (QLD) - Friday, Jul 01, 2005 at 07:42

Friday, Jul 01, 2005 at 07:42
ERUDITION - Deep, extensive learning. Profound scholarly knowledge

You must be thinking about another forum.

;-)
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FollowupID: 373524

Follow Up By: Alloy c/t - Friday, Jul 01, 2005 at 08:20

Friday, Jul 01, 2005 at 08:20
Nudenut , play the game ,your a fridgy arnt you , explain the concept and how a loaded fridge cycling on/off and maintaining a set temp uses less power per given time frame than the same fridge being switched off/on manually. lol.
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FollowupID: 373527

Follow Up By: Nudenut - Friday, Jul 01, 2005 at 08:25

Friday, Jul 01, 2005 at 08:25
hey who told you i was a fridgie....wait till i get my hands on him ! or her!
he ..or she must have erred lol lol

who was eh?

whats the question again?

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FollowupID: 373528

Follow Up By: Footloose - Friday, Jul 01, 2005 at 08:30

Friday, Jul 01, 2005 at 08:30
Careful Bob, your post primary education is showing and you know how jealous some people can get :))))))
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FollowupID: 373530

Follow Up By: Alloy c/t - Friday, Jul 01, 2005 at 08:37

Friday, Jul 01, 2005 at 08:37
Nudenut ,who told ? twas old drinking mates ,The Publican & The Undertaker lol.
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FollowupID: 373531

Reply By: Member - John C (QLD) - Friday, Jul 01, 2005 at 08:28

Friday, Jul 01, 2005 at 08:28
I think you may be missing the point. The idea is to slow those little bacteria growing in the food by giving them a hard life. Bugger the beer. (Can't believe I said that!!!).

Have old 39l engel.

So, we do leave our fridge on at night in hotter weather (more than 5deg C) and turn it down in colder weather. When 5 to 10deg at night, set at 1, when 10 to 15 at night, 1.5, when 15 plus leave at daytime setting. Trying to get a fridge temp of about 5degC.

You just need to keep the power up to it or you risk food poisoning, or throwing the food out.

If however you only live on beer, and only drink during the evening, and driving each day, do as you suggest, only run the fridge during the day :-)

AnswerID: 118358

Reply By: GreenTreeFrog - Friday, Jul 01, 2005 at 09:22

Friday, Jul 01, 2005 at 09:22
in our 4wd club we used to turn our fridges off at night till we found to many people were getting sicky from low grade food poisoning and one case that had to be taken to hospital. most in our club have now bought a small 110w solar kit with sealed battery and regulator for $1195 delivered
AnswerID: 118369

Reply By: Member - Collyn R (WA) - Friday, Jul 01, 2005 at 10:03

Friday, Jul 01, 2005 at 10:03
Theoretically the energy consumed must be the same, but if you are driving a fair distance that following day you could consider freezing a few of those blue 'cold' holders that you can buy in camping stores and using those as a cold store overnight. This will allow you to switch the fridge off at night at least in the cooler bits of Oz - but would not suggest doing so up north.

Another solutioon is sell the Engel and use an Autofridge. These only need running for only an hour or two morning and evening.
Collyn Rivers
AnswerID: 118376

Follow Up By: D-Jack - Friday, Jul 01, 2005 at 10:19

Friday, Jul 01, 2005 at 10:19
What a load of pigs testicles (which taste like ham I am told). Maybe in 5 degree temperatures, where my Engel would do the same thing anyway. Big call Collyn.
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FollowupID: 373546

Follow Up By: GreenTreeFrog - Friday, Jul 01, 2005 at 13:27

Friday, Jul 01, 2005 at 13:27
LOL that would mean you would freeze all the rest of the stuff in the fridge
frozen lettuce frozen milk frozen everything
the missses and kids would kill me
we can camp fulltime with the evakool and solar kit
bought another 40w panel and reggie and stick it on the start battery Exide Extreme to power the fluoro and radio
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FollowupID: 373584

Reply By: Member - Landie - Friday, Jul 01, 2005 at 10:51

Friday, Jul 01, 2005 at 10:51
We never turns ours off and never had a problem.

Turn it up during the day when travelling, turn it down at night....................
AnswerID: 118384

Reply By: Patrol22 (Queanbeyan - Friday, Jul 01, 2005 at 12:44

Friday, Jul 01, 2005 at 12:44
Gotta ask the question.....why bother turning it off? I never do as it is extremely rare for me to spend more than 4 days in the one spot and as yet my Waeco CCF45 has not discharged the battery (100ah deep cycle) to the point where the red light starts to flash.
AnswerID: 118401

Reply By: peter in sa - Friday, Jul 01, 2005 at 14:22

Friday, Jul 01, 2005 at 14:22
G'day Alex. I turn my fridge down to 1 at night and i have never had a problem with food nor drinks for that matter.When you get up early for a slash in the morning just go and turn it up for the day ahead. cheer's GREENDOG
AnswerID: 118413

Reply By: Member - Collyn R (WA) - Friday, Jul 01, 2005 at 15:57

Friday, Jul 01, 2005 at 15:57
D-Jack
I suspect you are unaware of how an Autofridge works. They have eutecic tanks that form the sides and end wall and base. These retain 'cold' for 10-12 hours after which the fridge needs to be turned on for one to two hours only. They are intended to be used this way.

Over that time the inside temperature typically stays within 2-3 degrees.

You may wish to believe this but an Autofridge will operate as above up here where I live (in the Kimberley) during the summer. Try that with your Engel!

Re the suggested cold blocks - if yiou have a freezer then freeze them - if not just let them cool in the fridge. Trust me, this really does work very well.
Collyn Rivers
AnswerID: 118424

Reply By: Mainey (WA) - Friday, Jul 01, 2005 at 17:53

Friday, Jul 01, 2005 at 17:53
Alex,
Take notice of 'GreenTreeFrog' and 'John C (QLD)'

I would think with an Engel it would not use much more power in the nite when it is not going to be opened anyway, and the more important aspect would be the physical health of your own family and friends who rely on the fridge to keep the food COLD, not just cool, if you want to save power and keep your food cool leave it outside in the nite.

Sounds like a fridge that draws too much power or a battery system that is too small!
AnswerID: 118440

Reply By: Member - Ray - Friday, Jul 01, 2005 at 18:49

Friday, Jul 01, 2005 at 18:49
Alex,
If I was you I would treat all responses except Collyns as well meaning amatuers but take all he says as gospel. If you do a bit if research into his credentials you will see what I mean.
Ray
AnswerID: 118455

Reply By: Truckster (Vic) - Saturday, Jul 02, 2005 at 00:22

Saturday, Jul 02, 2005 at 00:22
I wondered about this in the past, I used to unplug my Engel 40 at night, but last few trips, I have left it plugged in without any ill effects... It has been cold mostly at night though.
AnswerID: 118508

Reply By: Mainey (WA) - Saturday, Jul 02, 2005 at 00:51

Saturday, Jul 02, 2005 at 00:51
Ray,
Maybe he does not want to spend the money on buying a new Autofridge, I believe they are about $1800, so Alex asks the simple question; should the Engel be left on or turned off during the night to save power? Alex acknowledges that there will be various opinions and asks “what does anyone else reckon?”

Collyn did not mention the food may be contaminated due to it (possibly) getting too warm if the fridge is turned off, as the two posters I mentioned suggest that, it does not make them wrong, and if you read the thread again you will see that their posts were placed prior to Collyn's, and I would not be expecting him to restate the obvious fact that contaminated food is not good for your general health.

If you think their advice is not worthy of comment, that is your valued opinion, I believe it is important to be eating only food that will not make you sick while out in the bush and a full days drive from the nearest medical post, that probably does not have a resident doctor anyway, just a fly in once a week GP who was probably there yesterday and is not due back for six days, you have to actually live up in the bush to understand the risks.
(and yes, I know Collyn’s credentials quiet well, possibly better than most)

AnswerID: 118509

Reply By: Member - Collyn R (WA) - Saturday, Jul 02, 2005 at 09:36

Saturday, Jul 02, 2005 at 09:36
May I just add a further comment to this thread in relation to my suggestion of using 'cold-retaining blocks'.

The concept is this. If you are charging a battery by driving or using solar, and you have a relatively small capacity battery, it is often found that that battery will charge to as high is as the charging system will allow whilstv you bare vstill driving or whilst there is still solar irradiation available.

In that situation you now have the ability to store more energy and that otherwise non-utilised energy can readily be used to cool or freeze those blocks: it is the thermal equivalent of increasing battery capacity.

What you do with this stored thermal energy is up to you, but one immediate benefit is that the fridge will cycle far less overnight, your battery will be discharged less deeply and will thus last much longer.

I do not for an instance suggest you turn a freezer off overnight (and the original enquirer limited the discussion to fridges only) for the various reasons that people have already mentioned.
Collyn Rivers



AnswerID: 118521

Reply By: techo2oz - Saturday, Jul 02, 2005 at 21:24

Saturday, Jul 02, 2005 at 21:24
G'day,
I used to worry myself about this very same thing. I have an 80 Litre Waeco and in the middle of summer I would be anxious all night wondering if the batteries would hold up with the fridge running in Fridge/Freezer mode.

The key I have found is make sure you have a good battery and be able to replenish what is used through the day/night for those longer visits to the places we all love.

I now know that with my battery, I could last at the very least 3 days (and nights), fridge running in fridge/freezer mode without top up. But for piece of mind I use solar panels to put back in what the fridge and lights take out. {this way there is the hope the battery will last longer}.

I found that the fridge is self regulating anyway. Through the night, as ambient temps drop, while it still cycles, it cycles for less time. Thereby (as others have hinted at) ensuring your food does not spoil. It is best to try and keep food at a constant low temp. If it warms then cools etc, bacteria has more of a chance to form and hence more chance of you becoming crook.

So to finish, try it out at home for a while before going out. Use a indoor outdoor thermometer with min max readings (which are reasonably cheap) and see what the results would be. If you are at all worried, for the cost of the fridge and the benefit of your health, add bigger set of batteries and that way you can rest easy at night and your food (and drinks) will be safe.

Cheers

Peter
AnswerID: 118584

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