[NSRCA-discussion] E Stuff
Jay Marshall
lightfoot at sc.rr.com
Mon Jan 23 12:36:51 AKST 2006
Not quite. Voltage drop in wires and connectors are much higher at high
current ( I = E/R). For the same reasons power companies use very high
voltage transmission systems.
-----Original Message-----
From: nsrca-discussion-bounces at lists.nsrca.org
[mailto:nsrca-discussion-bounces at lists.nsrca.org] On Behalf Of Keith Hoard
Sent: Monday, January 23, 2006 10:46 AM
To: 'NSRCA Mailing List'
Subject: Re: [NSRCA-discussion] E Stuff
Aren't automobiles supposed to be going to higher voltage system due to all
of the electrical components people are adding to cars?
.
.
.
Wouldn't this also work for electric motors to reduce the amount of amps. .
. same number of cells, just run them all in series and reduce the current?
.
.
.
Isn't a Watt is a Watt; whether it is 100amps at 14 volts, or 100volts at 14
amps?
.
.
Maybe I should cut down the caffeine this early in the morning. . . .
Keith L. Hoard
Collierville, TN
khoard at midsouth.rr.com
_____
From: nsrca-discussion-bounces at lists.nsrca.org
[mailto:nsrca-discussion-bounces at lists.nsrca.org] On Behalf Of Dean Pappas
Sent: Monday, January 23, 2006 9:30 AM
To: NSRCA Mailing List
Subject: Re: [NSRCA-discussion] E Stuff
Hi Stu,
They'll quit at 10S, or 42VDC. That's the voltage above which electrical
codes (both local and international ) say you need to treat wiring as if it
was "mains" wiring, with insulation and creepage distance requirements. It's
not a big deal, really. You have a house full of wiring, including the power
supply of everything that plugs into a wall, that meets the requirements,
without having to do anything fancy. LiPoly is easier to construct for high
current discharge. With Li-iion, it is easier to get high energy density, at
the expense of current delivery. Some of the early 2S lithium-ion setups for
flight packs were actually dropping down below the regulator voltage
setpoint under peak loads. Don Szczur's Dad diagnosed that one, at least in
this part of the country. It's gotten better since then.
later,
Dean
Dean Pappas
Sr. Design Engineer
Kodeos Communications
111 Corporate Blvd.
South Plainfield, N.J. 07080
(908) 222-7817 phone
(908) 222-2392 fax
d.pappas at kodeos.com
-----Original Message-----
From: nsrca-discussion-bounces at lists.nsrca.org
[mailto:nsrca-discussion-bounces at lists.nsrca.org]On Behalf Of Stuart Chale
Sent: Monday, January 23, 2006 8:08 AM
To: 'NSRCA Mailing List'
Subject: Re: [NSRCA-discussion] E Stuff
I just read where Dewalt will also be offering Li-ion powered tools. I
think they are running at 32 volts. Didn't we start with 9.6? If this
keeps going you will be able to electrocute yourself with these tools soon
enough :-)
Is there a significant weight savings with Li-poly compared to Li-ion?
Stuart
_____
From: nsrca-discussion-bounces at lists.nsrca.org
[mailto:nsrca-discussion-bounces at lists.nsrca.org] On Behalf Of Dean Pappas
Sent: Sunday, January 22, 2006 5:59 PM
To: NSRCA Mailing List
Subject: Re: [NSRCA-discussion] E Stuff
Hi Stu,
As it turns out, Lithium Ion cells are just as touchy about overvoltage, and
the like. About 75 cell phones a year explode. A buddy of mine used to be
the strategic supply-line guy for Motorola phones. His contacts in the
engineering group there told me that Mot puts overvoltage protection,
internal cell pressure detection, over-current detection, and undervoltage
charge prevention protection in every pack/phone. That is what they
determined to be necessary to make litium ions acceptably safe. After all
that, you hear about problems, ususally with non OEM cells. Also since all
cell phones run with 1S packs, there are no balance issues.
I can see Milwaukee pack powered Sport stuff in our future, though! I'm
guessing they are 7S or 8S, based on the 28V marking on the box.
later,
Dean P.
-----Original Message-----
From: nsrca-discussion-bounces at lists.nsrca.org on behalf of Stuart Chale
Sent: Sat 1/21/2006 5:40 PM
To: 'NSRCA Mailing List'
Cc:
Subject: Re: [NSRCA-discussion] E Stuff
We already have two power tool companies with Li+ ion power packs. As I
understand it Li+poly are lighter per amount of energy but it seems more
dangerous with respect to charging. (any battery guru's are welcome to
better explain some of the differences, I would be more than interested).
I would suspect that saving a few ounces on a battery pack for a hand tool
if not as safe would not be in the toolmakers best interest.
Anyone know of other industries that would use LI+Poly and require the
discharging abilities that we do?
Also on a quick google search lithium fiber batteries popped up. Maybe
there is something even more promising on the horizon?
Personally I would like to see the next generation of batteries before
buying several sets.
Stuart
_____
From: nsrca-discussion-bounces at lists.nsrca.org
[mailto:nsrca-discussion-bounces at lists.nsrca.org] On Behalf Of
vicenterc at comcast.net
Sent: Saturday, January 21, 2006 5:12 PM
To: NSRCA Mailing List; NSRCA Mailing List
Cc: Jerry Stebbins
Subject: Re: [NSRCA-discussion] E Stuff
Jerry,
Today we got two e-mails. One with 30 cycles the other over 170. At the
Nats. a very well know pilot told me 60 average. As we can see, it is all
over the map. I would like to go electric and the advantages of electric
power in pattern are evident. However, I am not ready until battery
companies give us some minimum expectation in regard battery life. Clearly
time will tell. I believe that when we start to see the power tools
manufacturers installing LiPo in their equipment we would be able to expect
a decent life of this packs under high current draw conditions.
Vicente Bortone
-------------- Original message --------------
From: "Jerry Stebbins" <JAStebbins at worldnet.att.net>
Vicente, I hope that is "tongue in cheek", because any battery manufacturer
to warranty to that, or almost any extent would be killed by his/her
lawyers. They would have so many "exceptions" that they would "never be at
fault".
If that is anyone's criteria it wll be a long time before they switch.
Jerry
----- Original Message -----
From: vicenterc at comcast.net
To: NSRCA Mailing List <mailto:nsrca-discussion at lists.nsrca.org> ; NSRCA
Mailing List <mailto:nsrca-discussion at lists.nsrca.org>
Sent: Saturday, January 21, 2006 2:51 PM
Subject: Re: [NSRCA-discussion] E Stuff
Scott,
I am waiting for my second Abbra. If Tanic gives me a written warranty that
the battery is going to last around 250 cycles of Master rounds I will make
the switch. Is that possible? I will follow charging and break in
instructions.
Thanks
Vicente Bortone
-------------- Original message --------------
From: "Scott Anderson" <scott at rcfoamy.com>
Vicente,
You also have to look at replacing bearing, changing batteries in the
support equipment (glow driver/ electric starter) and servos after a time
from vibration, this will increase your glow cost per flight .. Dan Landis
and I are using Tanic packs and he flies FAI and has a set of sticks (
Battery) with over 170 flight and you can't tell the diffrence from that
pack and on with less time on it.. I have just started using Tanic and the
results are very good, Just follow there "breakin" for the packs.
I made the jump to electric in 05 and after the first flight I was hooked
and sold all glow fuel and glow planes.. If you look around you still make
the conversion without breaking the bank.
Just my 2 cents
Scott Anderson
D3 AVP nsrca 529
Team Tanicpacks.com
Team PMA
----- Original Message -----
From: vicenterc at comcast.net
To: NSRCA Mailing List <mailto:nsrca-discussion at lists.nsrca.org> ;
Discussion List, NSRCA <mailto:nsrca-discussion at lists.nsrca.org>
Sent: Saturday, January 21, 2006 1:35 PM
Subject: Re: [NSRCA-discussion] E Stuff
Unfurtunetely, I have to estimate the cost. I did an estimate how much is
the cost to run my 2c motor per flight. At $15/gallon using 14 oz of fuel
per fly the cost is $1.75 per flight. This number is correct since I
usually flight between 200-300 flights per year.
The question is: what is the life of the batteries? Base of the feedback I
got at the Nats. the life flying F3A is around 60 flights. Therefore, if I
am correct the cost per fly is $11. Assuming that I do 250 flights per year
the cost of electric is $2,750/yr. The equivalent cost of glow (2C) is
$440/year. With two kids in college my option is clear. I am assuming that
the cost of batteries is $640 but not sure now.
Probably I am wrong in these numbers. Clearly the cost of the batteries has
to come down or the cycles have to go up to around 400 cycles to get
equivalent cost to glow.
Any information on this regard is welcome,
Vicente Bortone
-------------- Original message --------------
From: "Earl Haury" <ehaury at houston.rr.com>
The E info on the list has been scant. Probably some are reluctant to hype /
criticize products because of their involvement with suppliers. Some of us
are just blindly exploring options, gathering data / information, and
forming opinions without experience to back up our conclusions. Certainly
information offered by those with experience is very welcome and
appreciated. Those who are qualified experts in the various fields that can
correct / clarify information gained through the school of hard knocks are
not only welcome, but I suspect somewhat obligated to protect the rest of
us. As this entire topic expands there will be conflicting opinions which in
themselves provide info - that's what this list is for and no one should
take offense that some prefer other views.
After teasing the E guys at the Nats I recognized that the E powered
airplanes flew better (I'll admit to being obstinate - but not totally
dumb). There were also differences that seemed related more to E equipment
choices than differences in pilot skills. The info published by Jason,
Frack, Adam, Chad, and others (in RCU forums) provided an insight to the
various equipment choices (and passionate defense of same in some cases).
Interestingly, a lot of the discussions revolve around equipment type rather
than the effect on flight characteristics.
So - I set about trying to determine if E flies better and why. So far the
answer is yes and I'm not sure. While differences in dynamics can be
identified, it's hard to quantify the effects. For example, the lighter /
slower rotating E prop generates a lower gyroscopic precession force during
looping maneuvers than glow - this also suggests the lower rotating mass of
a geared motor might be better. The lighter motor (compared to glow engine)
up front can result in a lower pitch moment of inertia if the tail is light
enough to allow the battery mass to be close to the CG. Airplane smoothness
in rough air is markedly better with E. (I did most of my comparisons with
twin Partners - one glow and one E - at about the same flight weight.) This
may be an effect of the large diameter prop or lack of vibration effect on
the servos. As others have noted, thrust application is very good with E as
the slower prop is efficient and the mo! ! ! tor is instantly responsive and
very linear. E can be flown slower than or as fast as glow, the airplane is
more stable with E when slow - again probably the large prop effect.
Overall, it's easier to fly well with E but E won't fix sloppy flying.
As with most things in model aviation - there are learning curves. Some
suppliers are better than others, some equipment is better than others, some
choices will be revisited after experience is gained. The hardest thing to
get used to is the metrification of cost - kilo dollars. Not that E is that
much more expensive than glow - just that very little from glow is useable
with E. That means one must acquire motors, controllers, batteries,
chargers, power supplies, meters, connectors, wire, props, etc. pretty much
from scratch.
If there's interest in this becoming a thread I'll discuss the reasons for
some of my choices of equipment and the data I've generated / will generate
with the full understanding that I might be operating under false
assumptions and some of this stuff will change - I'm still learning.
Earl
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