[NSRCA-discussion] Going Electric - Battery Questions

Fri Dec 7 14:35:29 AKST 2012

Larry,

I don't know the mechanics, I just know the result. Trust me. You take your
set up (BTW, I run a Himax with a 21 X 14) and run Sky lipo 4,400 20C's
versus Sky lipo 4,400 40C's and you will feel (see) a major difference.
There have been conversations on RC Groups about this very same subject.
Mike Mueller was saying he flew better with his older packs that weren't as
hot. I can tell, you it "does" make a difference...why, don't know.

I am currently running a Jeti 99. I also use an SD10G so I will get you my
throttle curve points to give you a starting place. As mentioned, with
every ESC you will most likely need a different curve.

On Fri, Dec 7, 2012 at 3:17 PM, Larry Diamond <ldiamond at diamondrc.com>wrote:

> 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
> heaics,t, 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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