[NSRCA-discussion] Going Electric - Battery Questions

Fri Dec 7 16:19:09 AKST 2012

If you go with 40C batteries, just add a couple head shims to the ESC.

Sent from my iPhone

On Dec 7, 2012, at 19:04, Ed Alt <ed_alt at hotmail.com> wrote:

  Assuming that you’re not discussing weighing the airplane for rules
compliance, a higher nitro percentage for a given volume of glow fuel
definitely does increase the weight of that volume of fuel, i.e., a heavier
takeoff weight.

Ed

 *From:* PhilS. <chuenkan at comcast.net>
*Sent:* Friday, December 07, 2012 7:44 PM
*To:* General pattern discussion <nsrca-discussion at lists.nsrca.org>
*Subject:* Re: [NSRCA-discussion] Going Electric - Battery Questions

Sorry, Verne, more Nitro doesn't cost us more weight.  ;-{)

Phil Spelt, KCRC President
AMA 1294 Scientific Leader Member
SPA 177 Board Member
(865)435-1476v, (865)604-0541c

On 12/7/2012 7:15 PM, Verne Koester wrote:

  Larry, 20C is 10% nitro, 40C is 40% nitro. Like nitro, more C is more
weight as well in most cases.

I fly Masters with 20C batteries and have my throttle governed back to make
it easier to manage the excess power. I started last season with 25C
batteries and had to govern it back even more. Using 40C batteries would be
like sticking a YS 170 on a 110-size plane while probably putting you over
the weight limit.

Verne

*From:* nsrca-discussion-bounces at lists.nsrca.org [
mailto:nsrca-discussion-bounces at lists.nsrca.org<nsrca-discussion-bounces at lists.nsrca.org>]
*On Behalf Of *Larry Diamond
*Sent:* Friday, December 07, 2012 6:18 PM
*To:* General pattern discussion
*Subject:* Re: [NSRCA-discussion] Going Electric - Battery Questions

Interesting point... I don't understand how changing from 20C to 40C pack
makes a difference using the same Motor and ESC combo. If it's battery
heat, my electronics background would tell me the pack is probably being
dicharged too deep. Not good for the life of a battery.

I suspect the result of not changing the Motor/ESC and only changing the
battery will reult in a shorter battery life; and, over loading the power
plant which will probably result in damaging the ESC and/or the Motor.

I could be wrong, cause I really have no experience with electric power set
ups in planes. I just don't understand the logic going from 20C to 40C and
the result being "too hot for intermediate".

It wouldn't surprise me to see Masters or FAI having a higher power set up,
like 3,500 to 4,000+ watts. Then depending on the max current draw,  40C
may make sense.

My set up will be about 2,700 to 3,000 watts based on specs... It may not
be sufficient for Masters or FAI.

Perhaps this will turn out to be a good constructive discussion for a
number of people like me, but I'm curious as to other opinions who have
practicle knowledge.

Larry Diamond

*From:* Patrick Harris <harris7148 at gmail.com>
*To:* General pattern discussion <nsrca-discussion at lists.nsrca.org>
*Sent:* Friday, December 7, 2012 2:02 PM
*Subject:* Re: [NSRCA-discussion] Going Electric - Battery Questions

Larry,

You have received all good advice. One thing to keep in mind, is you are
not going to be able to fly two full sequences with pretty much any setup.
With the Himax in a Monolog flying Intermediate, 20C's are going to be
perfect. With 20C's and good throttle management you are going to be able
to fly the full Intermediate and maybe four or five more maneuvers. If you
go up to 40C, you will find the Himax way to hot for Intermediate, and you
won't add that much flying time.

Another thing about the Himax is it really needs an aggressive throttle
curve on the bottom. If you just fly it out of the box it will have zip for
low end and nuts for high end all at about mid throttle. On the low end,
you will just keep pushing and pushing and nothing seems to happen until
you hit mid throttle and it will go nuts. The best throttle curve on my
Himax looks like a snake. It ramps up really fast on the low end, tappers
off at mid throttle and then heads back up on the high end, but you need to
work it out for your set up. Trust me, spending a good amount of time
getting this right is going to pay big dividends. If you don't, your
uplines are going  to be way too hot.

Hey Larry,

As everyone is telling you, the BIG difference between what you're
proposing and what you're accustomed to with Glg to below is that you'll
fly 90% of your sequence at half throttle.  Not figuratively half
throttle... but literally half, or below.  Even a vertical upline does not
need full motor on these setups.   Flying intermediate even less so.
Also, at full throttle you'll likely only pull about 75amps, so even 15C
batteries would get the job done, but I would stick with 20 and higher.

Mark Atwood
Paragon Consulting, Inc.  |  President
5885 Landerbrook Drive Suite 130, Cleveland Ohio, 44124
Phone: 440.684.3101 x102  |  Fax: 440.684.3102
mark.atwood at paragon-inc.com<mailto:mark.atwood at paragon-inc.com>  |
http://www.paragon-inc.com/<http://www.paragon-inc.com/>

On Dec 7, 2012, at 1:37 PM, Larry Diamond wrote:

OK, play nice... Never dealt with electrics before... I could be way off
base, but here is a stab at it...

Is my math flawed?

Motor - Himax 6330-210 F3A Motor (210KV)
ESC - Phoenix Ice 80HV - New V2 Version
Battery 10s - 37VDC

Plane - 2M Monolog

Max power range is about ~2,700 to ~3,000 watts with this set up...

Calculated Battery Discharge Rate = 80Amps (ESC rating) divided by 3,500mAh
(battery capacity) = 22.9C

Based on this math I suspect that a 30C dicharge rate is good on paper...
additional discharge performane = $$$ and I don't want to spend money on
battery performance I don't need...

Class - Intermediate

What is the recommended battery capacity and discharge rate...?

I understand the many variables associated with the answer like, prop size,
temps, wind, throttle control, yada, yada, yada...

I would like to fly the Intermediate sequence a couple time without having
to refuel electrons...

Larry Diamond
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