Warm air defrost for a Gizmo

13 messages

Warm air defrost for a Gizmo

Reply Threaded

I have a Gizmo (see tag line) and I periodically need to defrost the
windshield. Since I live in the rainy Pacific Northwest I frequently
have condensation on the inside and dew on the outside of my
windshield. Right now I have a muffin fan/computer fan blowing up
against the center of the windshield. You can see the fan grill in
this photo: http://www.evalbum.com/popupimg.php?6920 . I have a narrow
space below the fan where I would like to install some sort of heating
element. Since the DC-DC is maxed out with other loads I am thinking I
would like to hook something to the pack directly. Right now I have a
48V set of floodies but will be going to Lithiums soon. I need a
heating element that will handle upto 70V or so. Since the Gizmo does
not have a sealed cabin I'm not interested in heating it. I'm just
interested in raising the temperature of the air a little so that it
will clear the windshield without having to wipe it. Generally, once
the windshield is clear it stays clear if either the fan is running
and/or I'm driving. I presume an increase of 10 degrees or so would be
enough to clear the window if it isn't freezing outside.

I have a couple of ideas I want some input on. Since I don't want to
melt the existing plastic fan I need a low power solution. I took
apart a 12V auto defroster which runs off the cigarette lighter. I
think it is only a 150W unit. It has three approximately 1.5cm square
heating elements sandwiched between a couple of metal plates to which
the wiring is attached. I was wondering a couple of things. First,
what happens to the current and temperatur if I run the units at a
voltage lower than rated. Second, if I were to separate the three
elements and wire them in series would I essentially make a 36V unit
out of it? If things wouldn't get too hot I figure I could wire 6 of
the elements in series and have a unit which wouldn't put out too much
heat and would handle a wide range of pack voltage. Furthermore, it
would be thin enough to fit in the space I have available.

Thank you for any thoughts.

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

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Louis Pelletier

Re: Warm air defrost for a Gizmo

Reply Threaded

when i was a young un and drove a VW bug in the winter
i had the same problem. my fix was to sew up a small
bag and filled it with rock salt. wipe the windshield and
it would keep it clear for quite a while

Louis in central BC
----- Original Message -----
From: "David Nelson" <[hidden email]>
.

>I have a Gizmo (see tag line) and I periodically need to defrost the
> windshield. Since I live in the rainy Pacific Northwest I frequently
>.>

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Curtis Keller

Re: Warm air defrost for a Gizmo

Reply Threaded

Never living up North - I don't know if the rock salt is a standard
trick. But I'll give it a try in Dallas - in a month or two, when we
start having a freezing condensate issue.

On 11/8/09, Louis Pelletier <[hidden email]> wrote:

> when i was a young un and drove a VW bug in the winter
> i had the same problem. my fix was to sew up a small
> bag and filled it with rock salt. wipe the windshield and
> it would keep it clear for quite a while
>
> Louis in central BC
> ----- Original Message -----
> From: "David Nelson" <[hidden email]>
> .
>
>
>>I have a Gizmo (see tag line) and I periodically need to defrost the
>> windshield. Since I live in the rainy Pacific Northwest I frequently
>>.>
>
> _______________________________________________
> General EVDL support: http://evdl.org/help/
> Usage guidelines: http://evdl.org/help/index.html#conv
> Archives: http://evdl.org/archive/
> Subscription options: http://lists.sjsu.edu/mailman/listinfo/ev
>
>

--
Sent from my mobile device

Curtis Keller
[hidden email]

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Roland Wiench

Re: Warm air defrost for a Gizmo

Reply Threaded

In reply to this post by David Nelson-5

Hello David,

I use a in cab heater that is 640 watts 120 vac on the driver side, which is
mounted back under the dash. You can get these heaters from a auto parts
store.

Here in Montana, I only had to use one 640 watt heater. Never use the 840
watt on the passenger side and the 1000 watt hot water heater core so far.
The winters here had been warmer or above 0 F. for the last 15 years.

At first, I just install this unit connecting to a 20 amp fusetron or you
can use a 20 amp circuit breaker. This is tap off my main AC input plug.
Leave the heater control on, and I just turn on a 20 amp 120 VAC toggle
switch to turn it on about 30 minutes before I leave. It gets the cab up to
80 F. and warms the seat up too.

If I am only driving 5 miles, this will keep all the glass defrosted.
Latter, I added a alternator-inverter which is ran off the pilot shaft of
the motor which provides 145 amps at 13.5 to 16 volts and at the same time
can provide 3 kw at 120 VAC 60 HZ at the same time or up to 7 kw if the 12
volt is kept low.

I run all my heaters, fans, pumps, accessory motors all rated at 120 volts
60 hz. Do not have to get something special or modified any of these units
to run off the pack voltage.

I only have to use the on board system after I have been park outside a
while and I found I can defrost the windshield in less than a 5 minutes and
never need it again for the next 5 miles.

You could also use a DC-DC converter that is rated at a minimum of 55 amp at
14.5 VDC to run a small .75 to 1 kw inverter to run just the heater. I use
a on dash double pole double throw three position 120 volt 20 amp rocker
switch to either turn on the heater using the on board inverter or switch to
the outboard AC power while it is park and plug in.

The advantage with the rotary inverter-alternator, is that when I am going
down long steep hills, the main battery amps is at 0 amps and the motor
inertia is generating the 12 and 120 volt power, which also provides a
regenerative breaking.

I also use another on dash selector switch with can either select the the
main motor to drive the inverter-alternator while going down hill or any
time I lift up on the accelerator. Press the accelerator it than disconnect
the motor drive to this unit.

Roland

----- Original Message -----
From: "David Nelson" <[hidden email]>
To: "Electric Vehicle Discussion List" <[hidden email]>
Sent: Sunday, November 08, 2009 5:56 PM
Subject: [EVDL] Warm air defrost for a Gizmo

> I have a Gizmo (see tag line) and I periodically need to defrost the
> windshield. Since I live in the rainy Pacific Northwest I frequently
> have condensation on the inside and dew on the outside of my
> windshield. Right now I have a muffin fan/computer fan blowing up
> against the center of the windshield. You can see the fan grill in
> this photo: http://www.evalbum.com/popupimg.php?6920 . I have a narrow
> space below the fan where I would like to install some sort of heating
> element. Since the DC-DC is maxed out with other loads I am thinking I
> would like to hook something to the pack directly. Right now I have a
> 48V set of floodies but will be going to Lithiums soon. I need a
> heating element that will handle upto 70V or so. Since the Gizmo does
> not have a sealed cabin I'm not interested in heating it. I'm just
> interested in raising the temperature of the air a little so that it
> will clear the windshield without having to wipe it. Generally, once
> the windshield is clear it stays clear if either the fan is running
> and/or I'm driving. I presume an increase of 10 degrees or so would be
> enough to clear the window if it isn't freezing outside.
>
> I have a couple of ideas I want some input on. Since I don't want to
> melt the existing plastic fan I need a low power solution. I took
> apart a 12V auto defroster which runs off the cigarette lighter. I
> think it is only a 150W unit. It has three approximately 1.5cm square
> heating elements sandwiched between a couple of metal plates to which
> the wiring is attached. I was wondering a couple of things. First,
> what happens to the current and temperatur if I run the units at a
> voltage lower than rated. Second, if I were to separate the three
> elements and wire them in series would I essentially make a 36V unit
> out of it? If things wouldn't get too hot I figure I could wire 6 of
> the elements in series and have a unit which wouldn't put out too much
> heat and would handle a wide range of pack voltage. Furthermore, it
> would be thin enough to fit in the space I have available.
>
> Thank you for any thoughts.
>
> --
> David D. Nelson
> http://evalbum.com/1328
>
> _______________________________________________
> General EVDL support: http://evdl.org/help/
> Usage guidelines: http://evdl.org/help/index.html#conv
> Archives: http://evdl.org/archive/
> Subscription options: http://lists.sjsu.edu/mailman/listinfo/ev
>
>

Mike Nickerson

Re: Warm air defrost for a Gizmo

Reply Threaded

Hi Roland,

I really like the idea of using the alternator off the pilot shaft to
provide regenerative braking and power for climate control accessories
without using pack voltage.

I'm curious how you switch that alternator drive in and out when you let off
and push down on the accelerator. Could you go into more detail on that?
Are you doing that manually with the switch, or is there some automatic
sensing going on?

It sounds like a great idea that I'd like to incorporate into my EV when I
finally get that far.

Thanks,

Mike

-----Original Message-----
From: [hidden email] [mailto:[hidden email]] On Behalf
Of Roland Wiench
Sent: Sunday, November 08, 2009 8:41 PM
To: Electric Vehicle Discussion List
Subject: Re: [EVDL] Warm air defrost for a Gizmo

Hello David,

I use a in cab heater that is 640 watts 120 vac on the driver side, which is

mounted back under the dash. You can get these heaters from a auto parts
store.

Here in Montana, I only had to use one 640 watt heater. Never use the 840
watt on the passenger side and the 1000 watt hot water heater core so far.
The winters here had been warmer or above 0 F. for the last 15 years.

At first, I just install this unit connecting to a 20 amp fusetron or you
can use a 20 amp circuit breaker. This is tap off my main AC input plug.
Leave the heater control on, and I just turn on a 20 amp 120 VAC toggle
switch to turn it on about 30 minutes before I leave. It gets the cab up to

80 F. and warms the seat up too.

If I am only driving 5 miles, this will keep all the glass defrosted.
Latter, I added a alternator-inverter which is ran off the pilot shaft of
the motor which provides 145 amps at 13.5 to 16 volts and at the same time
can provide 3 kw at 120 VAC 60 HZ at the same time or up to 7 kw if the 12
volt is kept low.

I run all my heaters, fans, pumps, accessory motors all rated at 120 volts
60 hz. Do not have to get something special or modified any of these units
to run off the pack voltage.

I only have to use the on board system after I have been park outside a
while and I found I can defrost the windshield in less than a 5 minutes and
never need it again for the next 5 miles.

You could also use a DC-DC converter that is rated at a minimum of 55 amp at

14.5 VDC to run a small .75 to 1 kw inverter to run just the heater. I use
a on dash double pole double throw three position 120 volt 20 amp rocker
switch to either turn on the heater using the on board inverter or switch to

the outboard AC power while it is park and plug in.

The advantage with the rotary inverter-alternator, is that when I am going
down long steep hills, the main battery amps is at 0 amps and the motor
inertia is generating the 12 and 120 volt power, which also provides a
regenerative breaking.

I also use another on dash selector switch with can either select the the
main motor to drive the inverter-alternator while going down hill or any
time I lift up on the accelerator. Press the accelerator it than disconnect

the motor drive to this unit.

Roland

----- Original Message -----
From: "David Nelson" <[hidden email]>
To: "Electric Vehicle Discussion List" <[hidden email]>
Sent: Sunday, November 08, 2009 5:56 PM
Subject: [EVDL] Warm air defrost for a Gizmo

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David Roden-3

Re: Warm air defrost for a Gizmo

Reply Threaded

In reply to this post by David Nelson-5

When I was a pup, just about every discount store's auto department sold
"infrared windshield defrosters." They were bar-shaped, maybe a foot and a
half or a couple of feet long. They stuck on the inside of your windshield
with suction cups, and usually plugged into the cigar lighter receptacle.

They worked, after a fashion. Some of the original Citicars came with these
as factory defrosters!

I haven't seen one offered for many years, but they might be worth looking
for or even making. I've often thought that something similar ought to work
for a small EV. In fact it might be ideal for your situation, since you
want to warm the windshield itself, not the air in the vehicle. And yes,
I'd guess that in most cases 3 of them in series would work fine on a 36v
battery.

FYI, if you halve the voltage applied to the heater, its output falls to one-
quarter (that is, wattage varies as the square of the voltage).

David Roden - Akron, Ohio, USA
EVDL Administrator

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David Nelson-5

Re: Warm air defrost for a Gizmo

Reply Threaded

On Sun, Nov 8, 2009 at 10:20 PM, EVDL Administrator <[hidden email]> wrote:
[snip]
> I've often thought that something similar ought to work
> for a small EV. In fact it might be ideal for your situation, since you
> want to warm the windshield itself, not the air in the vehicle. And yes,
> I'd guess that in most cases 3 of them in series would work fine on a 36v
> battery.
>
> FYI, if you halve the voltage applied to the heater, its output falls to one-
> quarter (that is, wattage varies as the square of the voltage).

That is what I was looking for. From that I assume I can calculate
current draw to make sure I get a relay able to handle the load. Also,
if I get too much heat out I can add another one in series to lower
the heat output or add a resistor which can handle the load.

The windshield is made out of lexan and is quite curved so something
warming the air looks like the best bet.

Thank you.

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

_______________________________________________
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Usage guidelines: http://evdl.org/help/index.html#conv
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Roland Wiench

Re: Warm air defrost for a Gizmo

Reply Threaded

In reply to this post by Mike Nickerson

Hello Mike,

There are two ways to do shut down the alternator or any other power
sourced. If you have a three wire alternator which are normally the older
style which use a control lead from the ignition switch, you just insert a
manual switch or a relay control from a micro switch on the accelerator
lever to open this alternator circuit.

When this circuit is open, the alternator will not generate any power thus
no load. The same with the Air Conditional, just cut the power to the
clutch circuit on the AC.

During this time the alternator is off the line, a large deep cycle 12 volt
battery is providing the electric power steering and controller.

The second way, is to have the pilot shaft of the motor disconnect from the
alternator by the use of a shaft clutch. These are inline type of coupler
shafts made by Dodge Power Transmission at a cost of about $1600.00. I did
not have the room to install this type of clutch coupler, so I install a
double cog industrial belt from a double pulley on the main motor that
connected to pulley on a electric clutch that is normally use for a A/C
unit.

To mount this A/C clutch, you need a very sturdy support to hold two face
bearing plates that supports the clutch drive shaft. I use a large aluminum
plate that is 1/2 inch thick that not only supports this clutch unit, but
also the inverter-alternator, the A/C unit, the Vacuum pump, vacuum
canister, the hot water heater pump, and two accessory drive motors.

This accessory mount is pattern off a GMC diesel mount which is bolted to
the front of the engines. It has all the adjusting mechanisms for these
units and idling pulleys. This unit is place about 12 inches in front of
the main motor and has it own mounting to four engine type donuts that are
place on two cross members bolted to the frame rails.

Now if I need additional power while the main motor is disengaged, I can
turn on a switch to turn on a electric motor to drive any one of these units
by use of the common belt drive. I been thinking of using four paddle
switches on the steering column made by TCI.COM that are normally use for
shifting a transmission to control this function.

Roland

----- Original Message -----
From: "Mike Nickerson" <[hidden email]>
To: "'Electric Vehicle Discussion List'" <[hidden email]>
Sent: Sunday, November 08, 2009 8:37 PM
Subject: Re: [EVDL] Warm air defrost for a Gizmo

> Hi Roland,
>
> I really like the idea of using the alternator off the pilot shaft to
> provide regenerative braking and power for climate control accessories
> without using pack voltage.
>
> I'm curious how you switch that alternator drive in and out when you let
> off
> and push down on the accelerator. Could you go into more detail on that?
> Are you doing that manually with the switch, or is there some automatic
> sensing going on?
>
> It sounds like a great idea that I'd like to incorporate into my EV when I
> finally get that far.
>
> Thanks,
>
> Mike
>
> -----Original Message-----
> From: [hidden email] [mailto:[hidden email]] On
> Behalf
> Of Roland Wiench
> Sent: Sunday, November 08, 2009 8:41 PM
> To: Electric Vehicle Discussion List
> Subject: Re: [EVDL] Warm air defrost for a Gizmo
>
> Hello David,
>
> I use a in cab heater that is 640 watts 120 vac on the driver side, which
> is
>
> mounted back under the dash. You can get these heaters from a auto parts
> store.
>
> Here in Montana, I only had to use one 640 watt heater. Never use the 840
> watt on the passenger side and the 1000 watt hot water heater core so far.
> The winters here had been warmer or above 0 F. for the last 15 years.
>
> At first, I just install this unit connecting to a 20 amp fusetron or you
> can use a 20 amp circuit breaker. This is tap off my main AC input plug.
> Leave the heater control on, and I just turn on a 20 amp 120 VAC toggle
> switch to turn it on about 30 minutes before I leave. It gets the cab up
> to
>
> 80 F. and warms the seat up too.
>
> If I am only driving 5 miles, this will keep all the glass defrosted.
> Latter, I added a alternator-inverter which is ran off the pilot shaft of
> the motor which provides 145 amps at 13.5 to 16 volts and at the same time
> can provide 3 kw at 120 VAC 60 HZ at the same time or up to 7 kw if the 12
> volt is kept low.
>
> I run all my heaters, fans, pumps, accessory motors all rated at 120 volts
> 60 hz. Do not have to get something special or modified any of these
> units
> to run off the pack voltage.
>
> I only have to use the on board system after I have been park outside a
> while and I found I can defrost the windshield in less than a 5 minutes
> and
> never need it again for the next 5 miles.
>
> You could also use a DC-DC converter that is rated at a minimum of 55 amp
> at
>
> 14.5 VDC to run a small .75 to 1 kw inverter to run just the heater. I
> use
> a on dash double pole double throw three position 120 volt 20 amp rocker
> switch to either turn on the heater using the on board inverter or switch
> to
>
> the outboard AC power while it is park and plug in.
>
> The advantage with the rotary inverter-alternator, is that when I am going
> down long steep hills, the main battery amps is at 0 amps and the motor
> inertia is generating the 12 and 120 volt power, which also provides a
> regenerative breaking.
>
> I also use another on dash selector switch with can either select the the
> main motor to drive the inverter-alternator while going down hill or any
> time I lift up on the accelerator. Press the accelerator it than
> disconnect
>
> the motor drive to this unit.
>
> Roland
>
>
>
>
> ----- Original Message -----
> From: "David Nelson" <[hidden email]>
> To: "Electric Vehicle Discussion List" <[hidden email]>
> Sent: Sunday, November 08, 2009 5:56 PM
> Subject: [EVDL] Warm air defrost for a Gizmo
>
>
> > I have a Gizmo (see tag line) and I periodically need to defrost the
> > windshield. Since I live in the rainy Pacific Northwest I frequently
> > have condensation on the inside and dew on the outside of my
> > windshield. Right now I have a muffin fan/computer fan blowing up
> > against the center of the windshield. You can see the fan grill in
> > this photo: http://www.evalbum.com/popupimg.php?6920 . I have a narrow
> > space below the fan where I would like to install some sort of heating
> > element. Since the DC-DC is maxed out with other loads I am thinking I
> > would like to hook something to the pack directly. Right now I have a
> > 48V set of floodies but will be going to Lithiums soon. I need a
> > heating element that will handle upto 70V or so. Since the Gizmo does
> > not have a sealed cabin I'm not interested in heating it. I'm just
> > interested in raising the temperature of the air a little so that it
> > will clear the windshield without having to wipe it. Generally, once
> > the windshield is clear it stays clear if either the fan is running
> > and/or I'm driving. I presume an increase of 10 degrees or so would be
> > enough to clear the window if it isn't freezing outside.
> >
> > I have a couple of ideas I want some input on. Since I don't want to
> > melt the existing plastic fan I need a low power solution. I took
> > apart a 12V auto defroster which runs off the cigarette lighter. I
> > think it is only a 150W unit. It has three approximately 1.5cm square
> > heating elements sandwiched between a couple of metal plates to which
> > the wiring is attached. I was wondering a couple of things. First,
> > what happens to the current and temperatur if I run the units at a
> > voltage lower than rated. Second, if I were to separate the three
> > elements and wire them in series would I essentially make a 36V unit
> > out of it? If things wouldn't get too hot I figure I could wire 6 of
> > the elements in series and have a unit which wouldn't put out too much
> > heat and would handle a wide range of pack voltage. Furthermore, it
> > would be thin enough to fit in the space I have available.
> >
> > Thank you for any thoughts.
> >
> > --
> > David D. Nelson
> > http://evalbum.com/1328
> >
> > _______________________________________________
> > General EVDL support: http://evdl.org/help/
> > Usage guidelines: http://evdl.org/help/index.html#conv
> > Archives: http://evdl.org/archive/
> > Subscription options: http://lists.sjsu.edu/mailman/listinfo/ev
> >
> >
>
> _______________________________________________
> General EVDL support: http://evdl.org/help/
> Usage guidelines: http://evdl.org/help/index.html#conv
> Archives: http://evdl.org/archive/
> Subscription options: http://lists.sjsu.edu/mailman/listinfo/ev
>
> _______________________________________________
> General EVDL support: http://evdl.org/help/
> Usage guidelines: http://evdl.org/help/index.html#conv
> Archives: http://evdl.org/archive/
> Subscription options: http://lists.sjsu.edu/mailman/listinfo/ev
>
>

Dennis Miles-2

Re: Warm air defrost for a Gizmo

Reply Threaded

In reply to this post by David Nelson-5

On Mon, Nov 9, 2009 at 1:29 AM, David Nelson <[hidden email]> wrote:

> On Sun, Nov 8, 2009 at 10:20 PM, EVDL Administrator <[hidden email]>
> wrote:
> [snip]
> > I've often thought that something similar ought to work
> > for a small EV. In fact it might be ideal for your situation, since you
> > want to warm the windshield itself, not the air in the vehicle. And yes,
> > I'd guess that in most cases 3 of them in series would work fine on a 36v
> > battery.
> >
> > FYI, if you halve the voltage applied to the heater, its output falls to
> one-
> > quarter (that is, wattage varies as the square of the voltage).
>
> That is what I was looking for. From that I assume I can calculate
> current draw to make sure I get a relay able to handle the load. Also,
> if I get too much heat out I can add another one in series to lower
> the heat output or add a resistor which can handle the load.
>
> The windshield is made out of lexan and is quite curved so something
> warming the air looks like the best bet.
>
> Thank you.
>
> --
> David D. Nelson
> http://evalbum.com/1328
>
> _______________________________________________
>
> David, I was going to recommend one of the "DIY" kits for rear window
> defrost but set up as several strips in parallel connected to other similar
> sections in series to work at more than 12 volts but not on Lexan. however
> 120 v. heat ribbons in various lengths are available thru "Plumbing Supply"
> as heaters to prevent frozen pipes outdoors in cold climates and one of
> those glued to the bottom frame of the windshield and run off of pack
> voltage if it is 96 to 144 vdc. For your 36 volt pack perhaps an oven or
> broiler element for an electric range, they are available in many shapes but
> run on 220 v. so power dissipation would be only 50 watts instead of 1800
> but 50 seems like a good power for windshield defogging.
>

Regards,
--
Dennis Miles, (Director / CEO)
Electric Vehicle Technical Institute Inc.
Tampa Bay Region, Florida, USA
Phone (863) 289 - 0690
"Mentoring, Small Group Instruction,
and Hands-On training
for the EV Technicians:
Building, Converting, Repairing,
and Servicing the
Electric Vehicles of Today,
and the Future."
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joe-22

Re: Warm air defrost for a Gizmo

Reply Threaded

Or perhaps a water heater element - they burn out at 240V when not immersed;
but has anyone tried them at 36V?

Joseph H. Strubhar

Web: www.gremcoinc.com

E-mail: [hidden email]

----- Original Message -----
From: "Dennis Miles" <[hidden email]>
To: "Electric Vehicle Discussion List" <[hidden email]>
Sent: Monday, November 09, 2009 6:14 AM
Subject: Re: [EVDL] Warm air defrost for a Gizmo

> On Mon, Nov 9, 2009 at 1:29 AM, David Nelson <[hidden email]> wrote:
>
>> On Sun, Nov 8, 2009 at 10:20 PM, EVDL Administrator <[hidden email]>
>> wrote:
>> [snip]
>> > I've often thought that something similar ought to work
>> > for a small EV. In fact it might be ideal for your situation, since
>> > you
>> > want to warm the windshield itself, not the air in the vehicle. And
>> > yes,
>> > I'd guess that in most cases 3 of them in series would work fine on a
>> > 36v
>> > battery.
>> >
>> > FYI, if you halve the voltage applied to the heater, its output falls
>> > to
>> one-
>> > quarter (that is, wattage varies as the square of the voltage).
>>
>> That is what I was looking for. From that I assume I can calculate
>> current draw to make sure I get a relay able to handle the load. Also,
>> if I get too much heat out I can add another one in series to lower
>> the heat output or add a resistor which can handle the load.
>>
>> The windshield is made out of lexan and is quite curved so something
>> warming the air looks like the best bet.
>>
>> Thank you.
>>
>> --
>> David D. Nelson
>> http://evalbum.com/1328
>>
>> _______________________________________________
>>
>> David, I was going to recommend one of the "DIY" kits for rear window
>> defrost but set up as several strips in parallel connected to other
>> similar
>> sections in series to work at more than 12 volts but not on Lexan.
>> however
>> 120 v. heat ribbons in various lengths are available thru "Plumbing
>> Supply"
>> as heaters to prevent frozen pipes outdoors in cold climates and one of
>> those glued to the bottom frame of the windshield and run off of pack
>> voltage if it is 96 to 144 vdc. For your 36 volt pack perhaps an oven or
>> broiler element for an electric range, they are available in many shapes
>> but
>> run on 220 v. so power dissipation would be only 50 watts instead of 1800
>> but 50 seems like a good power for windshield defogging.
>>
>
> Regards,
> --
> Dennis Miles, (Director / CEO)
> Electric Vehicle Technical Institute Inc.
> Tampa Bay Region, Florida, USA
> Phone (863) 289 - 0690
> "Mentoring, Small Group Instruction,
> and Hands-On training
> for the EV Technicians:
> Building, Converting, Repairing,
> and Servicing the
> Electric Vehicles of Today,
> and the Future."
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Lee Hart

Re: Warm air defrost for a Gizmo

Reply Threaded

The Gizmo has a lot of "flow through" ventilation. It's going to take
many watts of heat to warm up that windshield, since almost all the heat
will be lost to the rapidly circulating surrounding air.

What about adding a second thin plastic inner windshield? Space it an
inch or so away from the existing one. Use something like a hair dryer
to produce hot air to blow into the space between the inner and outer
windshields. This will confine the heat to exactly where you need it.
Rewire the nichrome element in the hair dryer to suit your pack voltage.

--
Lee A. Hart | Ring the bells that still can ring
814 8th Ave N | Forget the perfect offering
Sartell MN 56377 | There is a crack in everything
leeahart earthlink.net | That's how the light gets in -- Leonard Cohen

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David Nelson-5

Re: Warm air defrost for a Gizmo

Reply Threaded

I thought I'd wire the heating element separately from the fan. I need
the heat when the Gizmo has been parked outside for a while and
condensation has built up. Right now I turn on the fan as soon as I
get in and let it run a while. Sometimes it takes a long while. I'd
like to use warmer air than ambient while I'm stopped. Once I start
moving I rarely use the fan because of all the "flow through"
ventilation.

As for rewiring a hair dryer nichrome element for pack voltage do I
just measure along the wire until I reach the resistance I want for
the voltage I have? If I wire it for 65V I should be ok with just
about any voltage I may have in my pack. A lower voltage means less
heat. Is it W=i^2R? I should just look it up.

On Mon, Nov 9, 2009 at 10:12 PM, Lee Hart <[hidden email]> wrote:

> The Gizmo has a lot of "flow through" ventilation. It's going to take
> many watts of heat to warm up that windshield, since almost all the heat
> will be lost to the rapidly circulating surrounding air.
>
> What about adding a second thin plastic inner windshield? Space it an
> inch or so away from the existing one. Use something like a hair dryer
> to produce hot air to blow into the space between the inner and outer
> windshields. This will confine the heat to exactly where you need it.
> Rewire the nichrome element in the hair dryer to suit your pack voltage.
>
> --
> Lee A. Hart | Ring the bells that still can ring
> 814 8th Ave N | Forget the perfect offering
> Sartell MN 56377 | There is a crack in everything
> leeahart earthlink.net | That's how the light gets in -- Leonard Cohen
>
> _______________________________________________
> General EVDL support: http://evdl.org/help/
> Usage guidelines: http://evdl.org/help/index.html#conv
> Archives: http://evdl.org/archive/
> Subscription options: http://lists.sjsu.edu/mailman/listinfo/ev
>
>

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

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Lee Hart

Re: Warm air defrost for a Gizmo

Reply Threaded

David Nelson wrote:
> I thought I'd wire the heating element separately from the fan. I need
> the heat when the Gizmo has been parked outside for a while and
> condensation has built up.

One possibility is a thermostat that turns the heating element on when
the temperature is below some temperature. Digikey has #317-1076-ND that
switch on below 60 deg.F that are DC rated to 60v at 6 amps.

Or, a couple closely spaced wires on the windshield to form a moisture
detector. When there is water on the windshield, it produces an X
meghohm resistor between the two points, which is enough to turn on the
gate of a MOSFET to power the heating element. When the window dries,
the resistance becomes infinite, and a XX megohm resistor pulls the
MOSFET gate low.

> As for rewiring a hair dryer nichrome element for pack voltage do I
> just measure along the wire until I reach the resistance I want for
> the voltage I have?

Yes, that will work. But I'd be more inclined to pick the tap according
to how much heat I felt I needed. 48v worth of a 120v element is 40% of
its length. But you can raise or lower this to get a little more heat
(and higher current) or a little less.

Or, you can tap the element in the middle, and wire the two halves in
parallel. This cuts the voltage in half, but doubles the current, to
raise the wattage back toward its full 120v value.

> A lower voltage means less heat. Is it W=i^2R?

Correct!

--
Lee A. Hart | Ring the bells that still can ring
814 8th Ave N | Forget the perfect offering
Sartell MN 56377 | There is a crack in everything
leeahart earthlink.net | That's how the light gets in -- Leonard Cohen

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Usage guidelines: http://evdl.org/help/index.html#conv
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