[NSRCA-discussion] Heat Sinks

Fri Aug 1 11:43:49 AKDT 2008

Earl, it has been several years since I "played" with these devices to cool
electronic components. As I remember the cooling power is proportional to
the input power. They still require a heat sink. See
http://www.overclockers.com/tips45/  for some discussion on cooling CPUs.

IMHO, because of the power requirements, extra weight, and heat sink
requirements they would be totally unsuitable for a pattern plane. The idea
of a real heat sink, maybe with the fins as part of the skin of the plane
and in the airstream, and the LiPo cell edges bonded to the sink with
thermal compound, has some merit and may require some investigation - if
cooling is what we really want.

Jay Marshall 

-----Original Message-----
From: nsrca-discussion-bounces at lists.nsrca.org
[mailto:nsrca-discussion-bounces at lists.nsrca.org] On Behalf Of Earl Haury
Sent: Friday, August 01, 2008 3:21 PM
To: General pattern discussion
Subject: Re: [NSRCA-discussion] Heat Sinks

Jay

Is it possible to change the "set point" of these units by varying the input
voltage?

Earl

----- Original Message ----- 

From: Jay Marshall <mailto:lightfoot at sc.rr.com>  

To: jpavlick at idseng.com ; 'General pattern discussion'
<mailto:nsrca-discussion at lists.nsrca.org>  

Sent: Friday, August 01, 2008 2:04 PM

Subject: Re: [NSRCA-discussion] Heat Sinks

Peltiers are the units used in your car to provide a hot/cold portable food
container.

Jay Marshall 

-----Original Message-----
From: nsrca-discussion-bounces at lists.nsrca.org
[mailto:nsrca-discussion-bounces at lists.nsrca.org] On Behalf Of John Pavlick
Sent: Friday, August 01, 2008 11:44 AM
To: nsrca-discussion at lists.nsrca.org
Subject: Re: [NSRCA-discussion] Heat Sinks

Yup that's one application though not the most effective use. You wouldn't
want to dissipate a lot of energy like what this guy was trying to do. The
neat thing about Peltiers is they can heat and cool depending on which
direction the current flows. In other words, they can be used to control the
temperature (up or down) and they're solid state so there are no moving
parts. 

Of course they require power to operate and it probably wouldn't be
practical to use the batteries themselves as the source since you guys need
every last drop of energy in them to run the motor. 

Just something to think about. Kinda like a profile Pattern plane. LOL

John Pavlick

JEREMY CHINN <lagrue at hotmail.com> wrote: 

With much the same question in mind, I found this with Google.....

http://www.dansdata.com/peltprac.htm

> Date: Fri, 1 Aug 2008 09:24:56 -0500
> From: glmiller3 at suddenlink.net
> To: jpavlick at idseng.com; nsrca-discussion at lists.nsrca.org
> Subject: Re: [NSRCA-discussion] Heat Sinks
> 
> What the heck are Peltiers? Flying in LA I never have to worry about
batteries being too COOL!
> 
> I'm always looking for a way to improve heat exchange, though. 
> 
> G
> ---- John Pavlick <jpavlick at idseng.com> wrote: 
> 
> =============
> You didn't fly fast enough to heat them up! <LOL> Seriously, LiPOs perform
best within a certain temperature range. You electron heads should look into
something that can keep the batteries within this range. Maybe Peltiers?
These are nice because thay can generate heat OR provide a cooling effect.
If anyone wants to explore this I'd be glad to help.
> 
> John Pavlick
> 
> JEREMY CHINN <lagrue at hotmail.com> wrote:
> .hmmessage P { margin:0px; padding:0px } body.hmmessage { FONT-SIZE: 10pt;
FONT-FAMILY:Tahoma } The assessment on my Kudzu at the Nats was that my
batteries never even got to optimum operating temperature...... 
> 
> 
> ---------------------------------
> From: jpavlick at idseng.com
> To: nsrca-discussion at lists.nsrca.org
> Date: Thu, 31 Jul 2008 22:12:06 -0400
> Subject: Re: [NSRCA-discussion] Heat Sinks
> 
> Sounds heavy. Don't electric airplanes have trouble making weight (except
for Dave Lockhart's of course)? What are you guys doing for letting air in /
out of the fuse. Without proper airflow, even a good heat sink won't work.
Actually wouldn't it be better to make some kind of (light weight)
thermostatically controlled cooling system? Cold LiPOs don't make optimum
power.
> 
> John Pavlick
> http://www.idseng.com
> ----- Original Message ----- 
> From: Earl Haury 
> To: Discussion List, NSRCA 
> Sent: Thursday, July 31, 2008 9:49 PM
> Subject: [NSRCA-discussion] Heat Sinks
> 
> 
> We all tend to mount E batteries on some sort of wooden / carbon / nomex
shelf and tie them down with Velcro or a clamp plate - none of which are
very good at transferring heat. Possibly we could improve heat transfer from
the batts to the cooling air by using aluminum, or better yet - finned
aluminum heatsink material for the shelf / clamp. 
> 
> I've spent a fair bit of time trying for find appropriate heatsink
material online - something 4" long x 3" wide with a high count of thin,
maybe 1/4 high, fins might work. Unfortunately, there's tons of heatsink
material available from Newark, Mauser, etc. but it's difficult to find the
right stuff - especially material light enough for our use. The closest I've
come is Thermaflo # E1243, but I'm lacking a small quantity source. 
> 
> Anybody work with this stuff & have recommendations or sources?
> 
> Earl
> 
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