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Discussion Starter #1
Re: [EVDL] [seva] Cold weather operation of an EV

Cold weather takes a huge toll on the range of EVs. It appears to cut the
range of the
Mitsubishi iMiev almost in half, and cut the range of the Nissan Leaf by
20-40%. It is a very
large problem in search of a solution.

You can compute the BTUs needed to heat a room at this website:

http://www.hearth.com/calc/btucalc.html

I selected a cold climate (Michigan), poor insulation, and a volume of 12'
by 5' by 8' (it
assumes all ceilings are 8' tall). It computed that you need from 1200 to
2400 BTU/HR to heat
that room. Now the Leaf is built on the Nissan Versa platform, and that
appears to have an
interior volume of roughly 150 cubic feet, as per this URL:

http://www.nissanusa.com/versa/specifications-hatchback.html

Now 12 x 5 x 8 = 480 cu. ft, which is 3.2 times the volume of the
Versa/Leaf. However, the Leaf
will typically be traveling at 30 MPH which will suck extra heat out of the
car compared with a
room. Still, with only 1/3 the volume, you would think 2400 BTUs would be
enough. But to be on
the extra save side I assumed you need 5000 BTUs/HR, or about 1.5 KW.

Now one gallon of gasoline contains 115,000 BTUs:

http://bioenergy.ornl.gov/papers/misc/energy_conv.html

While gasoline is very inefficient at running motors, it is 100% efficient
at generating heat, so
5000 BTUs should last (115000/5000) = 23 hours. If we assume that the Leaf
averages 30 MPH, then
we get 23*30 = 690 miles/gallon. Since we don't use heat during the Summer,
and even during the
Winter we don't always use maximum heat, we can assume that we average about
1/3 the heat
capacity of the gasoline heater. That translates to 3*690 = 2070
miles/gallon. If we drive
12,000 miles/yr, that translates to 5.8 gallons/year.

Now 5.8 gallons/year is but 1-2% of the gasoline needed to run an ICE car
for a year. It seems a
VERY small price to pay for eliminating one of the biggest barriers to the
use of EVs. Yet,
Nissan, Mitsubishi, THINK, and other production EVs lack such a heater.

So am I missing something here, or are my calculations way off?

-- Larry Gales







Dan Bentler <[email protected]>wrote:

> Insulation is always your best dollar spent (there is a point of
> diminishing return though - probably around 2" of styrofoam depending on
> situation)
>
> BTU is defined as 1 pound water raised 1 degree Faren.
> Human is approximately 90% (??) water.
> 3412 BTU per Kw
>
> Heat pump will produce approx 2 to 3 times as much energy as if uses. Mine
> produces approx 12,000 BTU and uses 1 Kw (3412 BTU) including circ pumps.
> Heated seats make a lot of sense - after all you really do not care about
> anything else except keeping YOU (un's) heat loss to a minimum.
> Now all you need to do is defrost the windshield.
>
> Electric defrost is used in aircraft. It has been used for windshields in
> cars but from what I have read is problematic and has not achieved great
> success. Works fine for rear windows where you can have visible conductors
> in the glass.
> Dan Bentler
> ------------------------------
> *From:* G P <[email protected]>
> *To:* SEVA <[email protected]>
> *Sent:* Sat, November 20, 2010 5:41:28 PM
> *Subject:* Re: [seva] Cold weather operation of an EV
>
>
> That's an issue I've been considering with our kei car EV. How can you
> reduce the need for A/C and heat? So far the best things I've come up with
> are:
>
> -reflective/blocking film on windows
> -Insulation (yes, insulation in a car :p )
> -Heated/cooled seats
>
>
>
> On Wed, Nov 17, 2010 at 6:02 AM, Larry Gales <[email protected]>wrote:
>
>> It appears that cold temperatures strongly affect the performance of EVs.
>> One report I read was
>> that the Mitsubishi iMiev was getting 80-100 miles per charge in moderate
>> temperature, but more like
>> 50 in freezing weather.
>>
>> It appears that this is a result not only of the battery temperature but
>> also the energy needed to
>> heat the passenger compartment. While the Nissan Leaf can start out with a
>> warm battery/cabin when it
>> is hooked up for charging, for longer drives and when parked w/o a
>> charging station, it will get
>> cold in cold weather.
>>
>> I wonder if anyone has looked at the economics and fuel consumption of
>> providing a small
>> gasoline/propane heater to warm the battery and cabin? Would this consume
>> a lot of fuel? Also,
>> if the car is equipped with a heat pump, would the heat pump greatly
>> reduce the amount of fuel
>> needed to warm the car and battery?
>>
>> Any thoughts on this would be appreciated.
>>
>> Thanks,
>>
>> -- Larry Gales
>>
>>
>> --
>> Larry Gales
>>
>>
>> -----------------------------------------------------------
>> Visit the SEVA website at http://www.seattleeva.org
>> Our New Forums are at http://www.seattleeva.org/smf
>> If you wish to unsubscribe from this mailing, send mail to
>> [email protected] with a subject of: unsubscribe seva
>>
>>
>
>
> -----------------------------------------------------------
> Visit the SEVA website at http://www.seattleeva.org
> Our New Forums are at http://www.seattleeva.org/smf
> If you wish to unsubscribe from this mailing, send mail to
> [email protected] with a subject of: unsubscribe seva
>
>


--
Larry Gales
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Discussion Starter #2
Re: [EVDL] [seva] Cold weather operation of an EV

Larry, Just do what I do. Think WARM thoughts :)

(If you look at my car you will know why I have to do that.)

--
David D. Nelson
http://evalbum.com/1328

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Discussion Starter #3
Re: [EVDL] [seva] Cold weather operation of an EV

Here is a formula we use to calculate the btu/hr that is needed:

Knowns: 1000 Btus = 3412 watts

SF = square foot of the exterior surfaces

TD = Temperature Difference between the interior and
exterior ambient air.

R = The resistance of the wall between the interior and
exterior ambient air.

U Factor is equal to 1/R


Now the formula becomes: Btu/hr = SF x U x TD


Your 480 cubic feet is equal to four sides of 12' x 5' = 240 SF
and two sides of 5' x 5' = 50 SF for a total of 290 SF.

Lets say we made this box completely out of 1/8 inch thick glass which has a
R-Factor of 1.00.

Lets say we want to maintain a 100 degree difference between the inside and
outside or from -30 below to 70 above R.

Therefore: Btur = 290 x (1/1) x 100 = 29000 btur

Watt/hr = 29000/3412 = 8.5 kwr

It would take 8.5 kw to maintain 70F at 30 below

Now lets say the class area is about 2 feet x 34 feet that wrap around the
top half of the vehicle and you added soft 1 inch upholstery foam rubber
behind all your door panels and under the carpet, and that aluminize
insulation that looks like bubble wrap under the ceiling coving, then it
takes two calculations as:

1 inch foam rubber and that 1/2 aluminize is about 5 R-Factor.

For the glass: Btur = 34 sf x (1/1) x 100 TD = 3400 btur

For all other areas: Btur = 256 sf x (1/5) x 100 TD = 5120 btur

Total = 8520 btur

Total wattage - 8250 btur /3412 = 2.5 kw at 30 below

This is exactly what I have in my EV is two cab heaters mounted inside under
the dash against the fire wall. A 640 watt is on the driver side and 860
watt is on the passenger side and 1000 watt water heater for the existing
heater core which totals to 2500 watt.

For the last two winters which was warmer than normal which only got down to
0 F for a short time, I only had to use the 640 watt heater on my side. I
normally pre heat the EV while setting in a garage at 65 F which increases
to 70 F about 30 minutes before I leave. If I turn on only the 640 heater
about 15 minutes before I leave, it will raise the cab temperature to 80 F.
It only takes me about 15 minutes to drive, so a lot of times I do not need
to turn on the 120 vac 60 hz heaters using a on board DC-AC inverter system.

Roland







----- Original Message -----
From: "Larry Gales" <[email protected]>
To: "SEVA" <[email protected]>; "Electric Vehicle Discussion List"
<[email protected]>
Sent: Sunday, November 28, 2010 8:36 PM
Subject: Re: [EVDL] [seva] Cold weather operation of an EV


> Cold weather takes a huge toll on the range of EVs. It appears to cut the
> range of the
> Mitsubishi iMiev almost in half, and cut the range of the Nissan Leaf by
> 20-40%. It is a very
> large problem in search of a solution.
>
> You can compute the BTUs needed to heat a room at this website:
>
> http://www.hearth.com/calc/btucalc.html
>
> I selected a cold climate (Michigan), poor insulation, and a volume of 12'
> by 5' by 8' (it
> assumes all ceilings are 8' tall). It computed that you need from 1200 to
> 2400 BTU/HR to heat
> that room. Now the Leaf is built on the Nissan Versa platform, and that
> appears to have an
> interior volume of roughly 150 cubic feet, as per this URL:
>
> http://www.nissanusa.com/versa/specifications-hatchback.html
>
> Now 12 x 5 x 8 = 480 cu. ft, which is 3.2 times the volume of the
> Versa/Leaf. However, the Leaf
> will typically be traveling at 30 MPH which will suck extra heat out of
> the
> car compared with a
> room. Still, with only 1/3 the volume, you would think 2400 BTUs would be
> enough. But to be on
> the extra save side I assumed you need 5000 BTUs/HR, or about 1.5 KW.
>
> Now one gallon of gasoline contains 115,000 BTUs:
>
> http://bioenergy.ornl.gov/papers/misc/energy_conv.html
>
> While gasoline is very inefficient at running motors, it is 100% efficient
> at generating heat, so
> 5000 BTUs should last (115000/5000) = 23 hours. If we assume that the
> Leaf
> averages 30 MPH, then
> we get 23*30 = 690 miles/gallon. Since we don't use heat during the
> Summer,
> and even during the
> Winter we don't always use maximum heat, we can assume that we average
> about
> 1/3 the heat
> capacity of the gasoline heater. That translates to 3*690 = 2070
> miles/gallon. If we drive
> 12,000 miles/yr, that translates to 5.8 gallons/year.
>
> Now 5.8 gallons/year is but 1-2% of the gasoline needed to run an ICE car
> for a year. It seems a
> VERY small price to pay for eliminating one of the biggest barriers to the
> use of EVs. Yet,
> Nissan, Mitsubishi, THINK, and other production EVs lack such a heater.
>
> So am I missing something here, or are my calculations way off?
>
> -- Larry Gales
>
>
>
>
>
>
>
> On Sat, Nov 20, 2010 at 8:46 PM, Dan Bentler
> <[email protected]>wrote:
>
> > Insulation is always your best dollar spent (there is a point of
> > diminishing return though - probably around 2" of styrofoam depending on
> > situation)
> >
> > BTU is defined as 1 pound water raised 1 degree Faren.
> > Human is approximately 90% (??) water.
> > 3412 BTU per Kw
> >
> > Heat pump will produce approx 2 to 3 times as much energy as if uses.
> > Mine
> > produces approx 12,000 BTU and uses 1 Kw (3412 BTU) including circ
> > pumps.
> > Heated seats make a lot of sense - after all you really do not care
> > about
> > anything else except keeping YOU (un's) heat loss to a minimum.
> > Now all you need to do is defrost the windshield.
> >
> > Electric defrost is used in aircraft. It has been used for windshields
> > in
> > cars but from what I have read is problematic and has not achieved great
> > success. Works fine for rear windows where you can have visible
> > conductors
> > in the glass.
> > Dan Bentler
> > ------------------------------
> > *From:* G P <[email protected]>
> > *To:* SEVA <[email protected]>
> > *Sent:* Sat, November 20, 2010 5:41:28 PM
> > *Subject:* Re: [seva] Cold weather operation of an EV
> >
> >
> > That's an issue I've been considering with our kei car EV. How can you
> > reduce the need for A/C and heat? So far the best things I've come up
> > with
> > are:
> >
> > -reflective/blocking film on windows
> > -Insulation (yes, insulation in a car :p )
> > -Heated/cooled seats
> >
> >
> >
> > On Wed, Nov 17, 2010 at 6:02 AM, Larry Gales
> > <[email protected]>wrote:
> >
> >> It appears that cold temperatures strongly affect the performance of
> >> EVs.
> >> One report I read was
> >> that the Mitsubishi iMiev was getting 80-100 miles per charge in
> >> moderate
> >> temperature, but more like
> >> 50 in freezing weather.
> >>
> >> It appears that this is a result not only of the battery temperature
> >> but
> >> also the energy needed to
> >> heat the passenger compartment. While the Nissan Leaf can start out
> >> with a
> >> warm battery/cabin when it
> >> is hooked up for charging, for longer drives and when parked w/o a
> >> charging station, it will get
> >> cold in cold weather.
> >>
> >> I wonder if anyone has looked at the economics and fuel consumption of
> >> providing a small
> >> gasoline/propane heater to warm the battery and cabin? Would this
> >> consume
> >> a lot of fuel? Also,
> >> if the car is equipped with a heat pump, would the heat pump greatly
> >> reduce the amount of fuel
> >> needed to warm the car and battery?
> >>
> >> Any thoughts on this would be appreciated.
> >>
> >> Thanks,
> >>
> >> -- Larry Gales
> >>
> >>
> >> --
> >> Larry Gales
> >>
> >>
> >> -----------------------------------------------------------
> >> Visit the SEVA website at http://www.seattleeva.org
> >> Our New Forums are at http://www.seattleeva.org/smf
> >> If you wish to unsubscribe from this mailing, send mail to
> >> [email protected] with a subject of: unsubscribe seva
> >>
> >>
> >
> >
> > -----------------------------------------------------------
> > Visit the SEVA website at http://www.seattleeva.org
> > Our New Forums are at http://www.seattleeva.org/smf
> > If you wish to unsubscribe from this mailing, send mail to
> > [email protected] with a subject of: unsubscribe seva
> >
> >
>
>
> --
> Larry Gales
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> | Multiple-address or CCed messages may be rejected.
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Discussion Starter #4
Re: [EVDL] [seva] Cold weather operation of an EV

Larry> So am I missing something here, or are my calculations way off?

Calculation-wise I doubt you've missed anything, however there is the extra
space usage to consider (for both the gas/diesel/propane/whatever heater,
and the smallish fuel tank). There's also the stigma of using fossil fuel
to heat the car no matter how few gallons of the stuff you need to burn.

--
Skip Montanaro - [email protected] - http://www.smontanaro.net/

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| Multiple-address or CCed messages may be rejected.
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