[NSRCA-discussion] E Stuff
Dean Pappas
d.pappas at kodeos.com
Mon Jan 23 06:29:54 AKST 2006
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 <mailto:nsrca-discussion at lists.nsrca.org> List ;
Discussion List, <mailto:nsrca-discussion at lists.nsrca.org> NSRCA
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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