running engel overnight?
Submitted: Thursday, Jun 30, 2005 at 21:47
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Alex H
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
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.
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 - 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: 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: 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:
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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