Keeping batteries from loosing their cool

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pengyou
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Keeping batteries from loosing their cool

I have read of a technology for cooling things - the words slip my mind now, but maybe it was thermo-electric? I think it is used in portable coolers. I also believe that it is a relatively energy efficient way to cool - does not generate heat, as do conventional fridges and freezers. Would it help prolong battery life to use this kind of technology to keep batteries cool? Especially the Lixx kind?

marylandbob
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Re: Keeping batteries from loosing their cool

Thermoelectric cooling DOES generate heat! There is heat produced by the supplied electricity overcoming the resistance of the cooling module, and there is the pumped, or removed, heat to dispose of. This means that if whatever you are cooling generates 700 watts of heat, and you cool it thermoelectrically, you will have to dispose of MORE than 700 watts of heat, probably around 1,000 watts worth! (you would be getting rid of the original 700 watts, plus the 300 watts used by the module in moving the heat. To this also add the power and heat generated/used by any cooling fans) When powered, all thermoelectric modules have one side cool, and one side hot, dependingon electrityflow direction, just as refrigerators also have a hot and cold side.-Bob

Robert M. Curry

reikiman
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Re: Keeping batteries from loosing their cool

Y'all may have noticed I've gone to most of the electric motorcycle races this year.

The cooling systems they're installing are focused mostly on motor and controller. They haven't been putting cooling systems into the batteries.

Indicates to me that cooling the batteries isn't the issue.

- David Herron, The Long Tail Pipe, davidherron.com, 7gen.com, What is Reiki
- Electrified Electra To

marylandbob
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Re: Keeping batteries from loosing their cool

As far as (Modern) batteries go, heating of the lithium cells is generally much less of a problem than nickel-metal hydride cells of similar capacity, as the internal "resistance per volt" is usually much less with lithium, and maximum operating temperature is also higher for many lithium cells. This heating problem is one of the biggest drawbacks to using nickel-metal hydride in automotive applications in hot weather! (If you have 2 different 40AH 125 volt batteries,on constructed of 100 each ni-mh cells, having 2 milliohms resistance per cell, and the other battery constructed from 34 lithium cells with 3 milliohms resistance per cell, the lithium battery would have lower overall resistance-102 milliohms total, vs. 200 milliohms total for the ni-mh battery! Doubling the battery internal resistance results in twice as much internal heating, so the ni-mh battery would heat up more, even though each cell had less resistance, because more cells are used, with higher TOTAL resistance.-(At 200 amperes load, the voltage from the ni-mh battery would drop by about 40 volts, producing 8KW, or about 24,000 BTU of HEAT! This would be reduced to 20 volts, and 4 KW, or about 12,000 BTU with the lithium cells described.)This heat also represents lost/unusable battery capacity, as it is not used to propel the vehicle! -Bob

Robert M. Curry

Dauntless
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Re: Keeping batteries from loosing their cool

I would assume you are referring to a Peltier heat pump. http://www.heatsink-guide.com/peltier.htm

Sounds like another of those great chases to find very little. Not much elecricity to be had. Although I like the idea of being able to turn body heat into electricity during the summer, afterall when the heat is extracted from your body you'll cool off, without an air conditioner. So it would cool the batteries, etc.

Thermoelectric Generator to Turn Body Heat into Electricity

WHo dares, WINS!!!!

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