Mini fridge as a cooler?

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avronw
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Mini fridge as a cooler?

Has anyone thought of the feasibility of using the innards of one of those mini fridges as a potential plug in cooler for the Vectrix in hot climates?

Something like the following:
USB Fridge

-Avron

AndY1
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Re: Mini fridge as a cooler?

I think that USB's available power is only 2W or maybe 4W. That's way not enough to cool down the intake air of Vectrix.

marylandbob
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Re: Mini fridge as a cooler?

A device such as the one shown is unlikely to be able to even maintain a drink, such as the one shown, to a temperature of 40 degrees F. or lower in a 75 degree F. or warmer room! It is a "wishful thinking" novelty, with way too little thermal capacity!--Even the bigger units, that plug into a cigaret lighter of a car, have difficulty cooling anything substantial to or below 40 degrees F. on hot days! (They will delay the enevitable temperature rise, but fail miserably when compared to a REAL refrigerator, as they cannot maintain a wide (70 degree F.) temperature differential. If you look into and/or study thermodynamics and physics, you will quickly see that such a device has no chance of being any significant benefit in cooling the mass of the Vectrix battery!--Its effect would be similar to attempting to empty a full bathtub, while the supply water continues to run into it full force, by bailing it out with a tablespoon!-Forget it!-Bob

Robert M. Curry

Spaceangel
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Re: Mini fridge as a cooler?

Has anyone thought of the feasibility of using the innards of one of those mini fridges as a potential plug in cooler for the Vectrix in hot climates?

Why would one want to seriously shorten range? Peltier modules use an immense amount of electricity. At least each module uses 5 Ampere at 12.6 volt and ten of them in series is 5A *120 volt=600 watts plus the cost of Peltier unit? The Vectrix is expensive enough.
Ouch!

KB1UKU

avronw
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Re: Mini fridge as a cooler?

I probably should have clarified more on my thinking, but it was more along the lines of using something like this as a slow cooler for a standing bike, powered off an external supply, possibly even with a slow closed ventilation circuit connecting intakes to exhaust.

procrastination inc
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Re: Mini fridge as a cooler?

I just park mine under a verandah with the intake facing toward a low opening window of my air conditioned house.

Ambient temp 36. temp during charge started at 33 (3 hrs with fan running in cooled air before charging) finished charg at 31

Mik
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Re: Mini fridge as a cooler?

I probably should have clarified more on my thinking, but it was more along the lines of using something like this as a slow cooler for a standing bike, powered off an external supply, possibly even with a slow closed ventilation circuit connecting intakes to exhaust.

It all depends on circumstances:

If there is no cool air available, then an active cooling method is needed.

It's not as easy and cheap as free cool air, but it will open up some environments for EV's where they would otherwise fail.

It also depends on battery chemistry: There might be a future battery with extremely long cycle life, if kept at just the right temperature at all times. For such a battery it might be very sensible to build a complex fluid based, active cooling system around all cells, to keep them at exactly the same, correct temperature all the time.

Who knows, advanced battery systems might well spend a third of their energy just on maintaining themselves; if this is the price for extreme reliability and longevity, then they might be more energy efficient than currently available batteries. You need to take the "Grey Energy" amount into consideration: The energy to explore mining fields, did out the ingredients, smelter them, transport them, etc. etc. etc. It adds up big time.

Regenerative cooling, anyone?

That will of course be an option, one day. During winter, an advanced EV might use peltier devices to produce electricity out of the heat gradient between battery and atmosphere. In summer, it might pump in some electrons to cool the batteries. Even if it used half the batteries energy to keep it cool during a day parked in the sun, that would be much preferable to a severely imbalanced battery due to strong temperature gradients under the same conditions without active cooling!

Of course, when plugged in, the energy for cooling (or heating, of course, think Alaska or Siberia) would come from the grid.

The amount of energy needed to keep the battery cool during actual driving would not be all that great, given the poor ranges available today.

This information may be used entirely at your own risk.

There is always a way if there is no other way!

avronw
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Re: Mini fridge as a cooler?

This is more in line with what I was thinking. Using a peltier like the following to sit in the battery compartment and either contribute to cooling all the time while riding, or just when parked. Powered either by the batteries or by an external source.

This example claims to be a 400W, so I would presume this would be considerably better at cooling than a smaller ex-USB version?

http://cgi.ebay.com.au/400W-12V-Thermoelectric-Cooler-TEC-Peltier-Plate_W0QQitemZ200406198105QQcmdZViewItemQQptZAU_B_I_Electrica...

marylandbob
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Re: Mini fridge as a cooler?

TEN of those 400 watt units, wired in series would work, they could pump 1,700 watts of heat, if properly fitted to heat sinks with propercooling fans for the "HOT" side. Then you will require 26 amperes at 125-155 volts,(4,000 Watts!) plus perhaps another 200 watts ffor the cooling fans, to operate the cooler. If powered by the Vectrix battery, it would kill the battery in about one hour, or decrease range to less than 1/2 of present range! If powered by mains, you would require over 3 times as much A.C. power as now, because operating the cooler would requre more than twice as much energy as charging the battery! You need a cooler capable of removing more heat than generated by the battery to reduce its temperature below the surrounding temperaature, therefore, if you have 1,500 watts of heat produced, you must remove MORE than that! Such a cooler, in WORKING configuration, would add considerable weight and bulk to the vehicle--imagine a heat sink with fans, about 12 inches wide by 3 feet long, installed between your legs, over the battery.--As stated earlier, NO, I do not find this very practical! One thing that might be practical, to help cool the cells to nearer ambient temperature, and balance internal battery temperature, would be to insert copper tubing cooled copper plates between small groups of cells, and circulate coolant thru them and an external radiator with cooling fan. This could remove a large amount of heat using a small amount of electricity, perhaps only 150 watts-50 watts for the pump, and 100 watts for the fan.-This system would NOT cool to a temperature below surrounding air, but would help eliminate Hot spots" in the battery compartment.--Bob

Robert M. Curry

Mik
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Re: Mini fridge as a cooler?

The cooling device does not need to be able to remove all of the heat produced by charging or riding in "real time".

It could provide significant benefits even if it was only running when the charger is not on, during pre-cooling and during after-cooling periods.

You could have a system that draws 1600W for 8hrs prior to charging, allowing to start charging with a cool battery even in heat wave conditions. Once CP charging is complete, it could again start to draw power, just a little less until CC charging has finished.

This is all theoretical, I don't think it could easily be added to a VX-1. If it was to be added, then recirculation of air rather than sucking in of fresh (hot) air would be required.

This information may be used entirely at your own risk.

There is always a way if there is no other way!

garethjones
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Re: Mini fridge as a cooler?

I think that USB's available power is only 2W or maybe 4W. That's way not enough to cool down the intake air of Vectrix.

I think this is right...

marylandbob
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Re: Mini fridge as a cooler?

No way! A cooling device must remove the heat as fast as it is produced just to "Break Even" and maintain a temperature equal to ambient. On a hot day, if it was 100 degrees F, and your device produced 1500 watts of heat,(about 4,500 btu) the cooler would have to pump at least 1500 watts of heat to maintain 100 degrees F, and to reduce that relatively hot temperature to a more reasonable 75 degrees F. would require even more powerful cooling!-Most air cooling devices capable of such capacity require at least 750 watts of power to operate, and involve electromechanical systems with liquid/gaseous refridgerant. (Think:5,000 BTU air conditioner)Total heat to then be disposed of is equal to the origonal 1,500 watts, PLUS the 750 watts used by the cooler, or 2,250 watts! This requires a powerful fan and large heat dissapation surface. If your cooler removed LESS than the amount of heat produced, it would only slow the temperature rise, but it would NEVER keep the device as cool as, or cooler than, its surroundings.)

Robert M. Curry

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